Game 1Unit 2 of 101 hr learning time
It Carries Its Prize Home
Behaviour needs rhythm, not just rules: a one-byte mode flag gives the wisp a cycle — hunt, snuff, withdraw, rest — and every theft buys the lamplighter a window he can plan inside.
20% of The Long Night
You named it at the end of the last unit: the wisp is relentless, and relentless is bad. Not bad at its job — bad at being in a game. It snuffs a lamp and pivots instantly to the next target; you re-light, it returns; there is no moment where the square is yours. The playtest that shaped this game recorded the feeling verbatim: “a pain in the bum to win.” Maximum pressure at every second means pressure never varies, and pressure that never varies stops being information. You can’t plan against it; you can only endure it.
The oldest fix in the genre belongs to Namco. Pac-Man’s ghosts — already credited in this course for proving how little rule an “intent” needs — hide a second, subtler lesson: they don’t hunt continuously. On a timer they break off and scatter, each to its own corner, then return. Those exhalations are what make the inhalations frightening, and they’re what make the maze occasionally, briefly, yours. The wisp is about to learn the same manners, with a twist that fits this game’s fiction: it doesn’t retreat on a timer. It retreats because it took something — the night carries each stolen flame home.
Milestone 1 — the mode flag
One byte, draught_mode: 0 hunting, 1 withdrawing. The snuff sets it; arriving home clears it. While it’s set, the seek ignores every lamp and every flame — the target is home, full stop. That’s the entire architecture, and it’s worth pausing on what it is: your first behavioural state machine. Gloaming’s game_state switched whole screens; this flag switches what one creature wants, and the chase code beneath it neither knows nor cares which mode chose its target.
Step 1: hunt, snuff, withdraw — the mode decides what a beat means
+41-2
| 182 | 182 | ; --- and, in the far corner, something else --- | |
| 183 | 183 | ld a, DRAUGHT_COL0 | |
| 184 | 184 | ld (draught_col), a | |
| 185 | + | ld (draught_home_col), a ; and remember where home is — | |
| 185 | 186 | ld a, DRAUGHT_ROW0 | |
| 186 | 187 | ld (draught_row), a | |
| 188 | + | ld (draught_home_row), a ; the withdraw will need it | |
| 187 | 189 | ; the dark gathers before its first step — a beat to read | |
| 188 | 190 | ; the square before the hunt begins | |
| 189 | 191 | ld a, GATHER | |
| 190 | 192 | ld (draught_timer), a | |
| 191 | 193 | xor a | |
| 192 | 194 | ld (player_timer), a | |
| 195 | + | ld (draught_mode), a | |
| 193 | 196 | | |
| 194 | 197 | ; --- wipe the canvas --- | |
| 195 | 198 | ; The bitmap ($4000-$57FF) is the pixel layer; whatever was on | |
| ... | |||
| 701 | 704 | ld a, DRAUGHT_SPEED | |
| 702 | 705 | ld (draught_timer), a | |
| 703 | 706 | | |
| 707 | + | ; withdrawing? after a snuff the night carries its prize | |
| 708 | + | ; home before hunting again — behaviour is a MODE now, and | |
| 709 | + | ; the mode decides what this beat means | |
| 710 | + | ld a, (draught_mode) | |
| 711 | + | or a | |
| 712 | + | jr z, .hunt | |
| 713 | + | ld a, (draught_home_col) | |
| 714 | + | ld hl, draught_col | |
| 715 | + | cp (hl) | |
| 716 | + | jr nz, .whome | |
| 717 | + | ld a, (draught_home_row) | |
| 718 | + | ld hl, draught_row | |
| 719 | + | cp (hl) | |
| 720 | + | jr nz, .whome | |
| 721 | + | xor a ; home — the hunt resumes at once | |
| 722 | + | ld (draught_mode), a | |
| 723 | + | ld a, DRAUGHT_SPEED | |
| 724 | + | ld (draught_timer), a | |
| 725 | + | ret | |
| 726 | + | .whome: | |
| 727 | + | ld a, (draught_home_col) | |
| 728 | + | ld (seek_col), a | |
| 729 | + | ld a, (draught_home_row) | |
| 730 | + | ld (seek_row), a | |
| 731 | + | jp .chase | |
| 732 | + | .hunt: | |
| 704 | 733 | ; the lamplighter's flame is the first candidate... | |
| 705 | 734 | ld a, (lamp_col) | |
| 706 | 735 | ld c, a | |
| ... | |||
| 835 | 864 | ld (under_draught + 8), a | |
| 836 | 865 | call unlight_pip | |
| 837 | 866 | call warm_walls | |
| 867 | + | ld a, 1 ; the prize is taken — withdraw | |
| 868 | + | ld (draught_mode), a | |
| 838 | 869 | .nosnuff: | |
| 839 | 870 | call draw_draught | |
| 840 | 871 | ret | |
| ... | |||
| 913 | 944 | ; (leaving it beside the respawn made a catch strip every | |
| 914 | 945 | ; life in seconds once the draught learnt to hunt) | |
| 915 | 946 | call restore_draught | |
| 916 | - | ld a, DRAUGHT_COL0 | |
| 947 | + | ld a, (draught_home_col) | |
| 917 | 948 | ld (draught_col), a | |
| 918 | - | ld a, DRAUGHT_ROW0 | |
| 949 | + | ld a, (draught_home_row) | |
| 919 | 950 | ld (draught_row), a | |
| 920 | 951 | ld a, DRAUGHT_SPEED | |
| 921 | 952 | ld (draught_timer), a | |
| 953 | + | xor a ; already home — hunt on arrival | |
| 954 | + | ld (draught_mode), a | |
| 922 | 955 | call save_draught | |
| 923 | 956 | call draw_draught | |
| 924 | 957 | ret | |
| ... | |||
| 1300 | 1333 | draught_col: | |
| 1301 | 1334 | defb 28 | |
| 1302 | 1335 | draught_row: | |
| 1336 | + | defb 4 | |
| 1337 | + | draught_home_col: | |
| 1338 | + | defb 28 | |
| 1339 | + | draught_home_row: | |
| 1303 | 1340 | defb 4 | |
| 1341 | + | draught_mode: | |
| 1342 | + | defb 0 ; 0 = hunting, 1 = withdrawing home | |
| 1304 | 1343 | draught_timer: | |
| 1305 | 1344 | defb 16 | |
| 1306 | 1345 | player_timer: |
The complete step 1 program
; The Long Night — Unit 2: It Carries Its Prize Home
; Cumulative build; every step runs on its own. Narrative: the unit page.
; Behaviour needs rhythm, not just rules: hunt, snuff, withdraw, rest.
org 32768
COBBLE equ %00000001 ; PAPER black (0), INK blue (1) — dark ground
WALL equ %00001111 ; PAPER blue (1), INK white (7) — pale stone
WALL_BIT equ 3 ; the attribute bit that says "this is wall"
LAMP_ATTR equ %01000111 ; BRIGHT, PAPER black, INK white — his own light
LAMP_UNLIT equ %00000101 ; cold cyan INK on black PAPER — bit 3
; clear, so a lamp reads as floor
LAMP_LIT equ %01000110 ; BRIGHT yellow INK on black — a held flame
DRAUGHT_ATTR equ %01000101 ; the wisp: BRIGHT cyan on black — cold light
LIVES equ 3
LIFE_PIP equ %01010000 ; a life: BRIGHT red PAPER — a small ember
LIFE_BASE equ $5800 + 28 ; row 0, right of the ledge — three cells
DRAUGHT_SPEED equ 16 ; frames between the wisp's steps
DRAUGHT_COL0 equ 28 ; the corner the dark enters from
DRAUGHT_ROW0 equ 4
PIP_UNLIT equ %00101000 ; a cold pip: cyan PAPER, a solid block
PIP_LIT equ %01110000 ; a warm pip: BRIGHT yellow PAPER
PIP_BASE equ $5800 + 12 ; row 0, column 12 — the HUD ledge,
; eight cells, centred over the square
NUM_LAMPS equ 8
MSG_ATTR equ %01000111 ; message text: bright white on black
MSG_ROW equ 11
LOSE_COL equ 10 ; centres the eleven characters
WIN_COL equ 7 ; centres the seventeen characters
FONT equ $3C00 ; the ROM font, addressed so that
; ASCII x 8 lands on the right glyph
STATE_TITLE equ 0
STATE_PLAY equ 1
STATE_WIN equ 2 ; the night is held — the game is won
STATE_LOSE equ 3 ; night falls — the game is lost
LOCK equ 25 ; input-lock frames after entering a screen
SPEAKER equ %00010000 ; port $FE bit 4 — the beeper's one bit
TITLE_COL equ 12 ; GLOAMING, centred
PROMPT_COL equ 10 ; PRESS SPACE, centred
TITLE_ROW equ 8
PROMPT_ROW equ 14
CONT_ROW equ 16 ; "PRESS SPACE" under a win/lose line
START_COL equ 15 ; where the lamplighter begins
START_ROW equ 11
PLAYER_REPEAT equ 6 ; frames between steps while a key is held
GATHER equ 120 ; frames the dark gathers before its first step
KEYS_OP equ $DFFE ; half-row P O I U Y — bits 1 and 0
KEYS_Q equ $FBFE ; half-row Q W E R T — bit 0 is Q
KEYS_A equ $FDFE ; half-row A S D F G — bit 0 is A
KEYS_SPACE equ $7FFE ; half-row SPACE SYM M N B — bit 0
start:
; --- the border goes black — the night beyond the square ---
; Port $FE bits 0-2 set the BORDER colour. A = 0 = black.
ld a, 0
out ($FE), a
ld a, STATE_TITLE
ld (game_state), a
call draw_title_screen
im 1
ei
call chime_dusk ; after EI — the rests need the interrupt
main_loop:
halt
; the dispatch: each state names what a frame means — the
; title listens for a beginning, PLAY beats the game forward,
; WIN and LOSE hold the screen exactly as it stands
ld a, (game_state)
cp STATE_TITLE
jr z, .do_title
cp STATE_PLAY
jr z, .do_play
call end_step ; WIN or LOSE — wait for a key, then title
jr main_loop
.do_title:
call title_step
jr main_loop
.do_play:
call play_step
jr main_loop
; ----------------------------------------------------------------------------
; title_step — SPACE starts a fresh game.
; ----------------------------------------------------------------------------
title_step:
ld a, (input_lock)
or a
jr z, .tready
dec a
ld (input_lock), a
ret
.tready:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
ret nz
call init_game
ld a, STATE_PLAY
ld (game_state), a
ret
; ----------------------------------------------------------------------------
; end_step — WIN or LOSE: SPACE returns to the title.
; ----------------------------------------------------------------------------
end_step:
ld a, (input_lock)
or a
jr z, .eready
dec a
ld (input_lock), a
ret
.eready:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
ret nz
call draw_title_screen
call chime_dusk
ld a, LOCK
ld (input_lock), a
ld a, STATE_TITLE
ld (game_state), a
ret
; play_step — one beat of the game: ask the keyboard.
play_step:
call player_step
; contact can end the game mid-frame — if it did, stop here
ld a, (game_state)
cp STATE_PLAY
ret nz
call draught_step
ld a, (game_state)
cp STATE_PLAY
ret nz
; the win check, at the only beat the count can have changed
ld a, (lit_count)
cp NUM_LAMPS
ret nz
; the night is held — the lives you kept are the score
ld a, (lives)
ld hl, best_lives
cp (hl)
jr c, .nobest
ld (hl), a
.nobest:
call draw_win_screen
call fanfare_held
ld a, LOCK
ld (input_lock), a
ld a, STATE_WIN
ld (game_state), a
ret
; ----------------------------------------------------------------------------
; init_game — everything a fresh night needs, gathered from what was
; the boot sequence. Beginning is a callable thing now.
; ----------------------------------------------------------------------------
init_game:
xor a
ld (lit_count), a
ld a, LIVES
ld (lives), a
; --- place the lamplighter ---
; His position is data. Everything that draws him reads it.
ld a, START_COL
ld (lamp_col), a
ld a, START_ROW
ld (lamp_row), a
; --- and, in the far corner, something else ---
ld a, DRAUGHT_COL0
ld (draught_col), a
ld (draught_home_col), a ; and remember where home is —
ld a, DRAUGHT_ROW0
ld (draught_row), a
ld (draught_home_row), a ; the withdraw will need it
; the dark gathers before its first step — a beat to read
; the square before the hunt begins
ld a, GATHER
ld (draught_timer), a
xor a
ld (player_timer), a
ld (draught_mode), a
; --- wipe the canvas ---
; The bitmap ($4000-$57FF) is the pixel layer; whatever was on
; screen before us still lives there. Zero it so only our
; attribute colours show.
call clear_bitmap
; --- texture the ground ---
; Blit the cobble stipple into every cell's bitmap, rows 1-23.
; The attributes will colour these pixels in a moment.
call fill_ground
; --- wash in the cobbles ---
; Seed the first attribute cell, point DE one cell ahead, and
; let LDIR cascade the byte through all 768 cells.
ld hl, $5800
ld de, $5801
ld (hl), COBBLE
ld bc, 767
ldir
call warm_walls
call paint_buildings
; --- brick the walls ---
; Now that the wall cells are painted, fill_walls can read the
; map back and lay brick wherever the wall bit is set.
call fill_walls
call draw_pips
call draw_lives
call draw_lamps
; save what he is about to stand on, BEFORE the first draw
call save_under
call draw_lamp
call save_draught
call draw_draught
ret
; ----------------------------------------------------------------------------
; warm_walls — the square's edge, one attribute write per cell; the
; colour is no longer a constant but the wall_ramp entry for how many
; lamps are lit. Same painting loop as ever — only where C comes from
; has changed.
; ----------------------------------------------------------------------------
warm_walls:
ld a, (lit_count)
ld e, a
ld d, 0
ld hl, wall_ramp
add hl, de
ld c, (hl) ; the byte every wall cell gets
; the top wall: row 1 is 32 cells in a row from $5820
; (row 0 is kept back — it becomes the HUD later)
ld hl, $5820
ld b, 32
.wt:
ld (hl), c
inc hl
djnz .wt
; the bottom wall: row 23, 32 cells from $5AE0
ld hl, $5AE0
ld b, 32
.wb:
ld (hl), c
inc hl
djnz .wb
; the side walls: column 0 and column 31 of rows 1-23.
; Write the row's first cell, hop 31 cells to its last,
; then step a full row (32) down — 23 times.
ld hl, $5820
ld b, 23
.ws:
ld (hl), c
push hl
ld de, 31
add hl, de
ld (hl), c
pop hl
ld de, 32
add hl, de
djnz .ws
ret
; ----------------------------------------------------------------------------
; The beeper. One bit on port $FE: set it, wait, clear it, wait — a
; square wave by hand. C is the half-period (pitch: bigger is lower),
; B the number of cycles (duration). DI while it sounds: the 50 Hz
; interrupt would stretch random half-periods and buzz the tone.
; ----------------------------------------------------------------------------
beep:
di
.bcyc:
ld a, SPEAKER
out ($FE), a
ld a, c
.bd1:
dec a
jr nz, .bd1
xor a
out ($FE), a
ld a, c
.bd2:
dec a
jr nz, .bd2
djnz .bcyc
ei
ret
blip_lit: ; a rising third — the lamp catches
ld b, $17 ; C6
ld c, $67
call beep
ld b, $28 ; E6
ld c, $51
jp beep
chime_dusk: ; two cold tolls, then the motif far off
ld b, $84 ; A4
ld c, $F7
call beep
ld b, 10
call rest
ld b, $84 ; A4
ld c, $F7
call beep
ld b, 13
call rest
ld b, $92 ; E5
ld c, $A4
call beep
ld b, 4
call rest
ld b, $9D ; C5
ld c, $CF
jp beep
; rest — B frames of silence. Musical time rides the heartbeat: the
; gaps between notes are counted in HALTs, not busy-loops.
rest:
halt
djnz rest
ret
fanfare_held: ; THE NIGHT IS HELD — a rising run
ld b, $83 ; C5
ld c, $CF
call beep
ld b, 3
call rest
ld b, $A5 ; E5
ld c, $A4
call beep
ld b, 3
call rest
ld b, $C4 ; G5
ld c, $8A
call beep
ld b, 3
call rest
ld b, $FF ; C6, held — B only counts to 255,
ld c, $67
call beep
ld b, $FF ; so hold it by sounding it twice
ld c, $67
jp beep
sting_nightfall: ; NIGHT FALLS — two steps down, then dark
ld b, $53 ; E5
ld c, $A4
call beep
ld b, 4
call rest
ld b, $49 ; D5
ld c, $B8
call beep
ld b, 4
call rest
ld b, $DC ; A4, long — the night settles on it
ld c, $F7
jp beep
; ----------------------------------------------------------------------------
; Screens.
; ----------------------------------------------------------------------------
; draw_win_screen — lift the lamplighter off the board (restore his
; cell: the eighth lamp, lit, comes out of the buffer), then say it.
; draw_title_screen — sparse and suggestive: a black void, the name,
; the invitation. Everything else is left to the imagination, which
; is both the aesthetic and the budget.
draw_title_screen:
call clear_bitmap
ld hl, $5800
ld de, $5801
ld (hl), %00000000
ld bc, 767
ldir
ld hl, title_text
ld b, TITLE_ROW
ld c, TITLE_COL
call print_string
ld hl, prompt_text
ld b, PROMPT_ROW
ld c, PROMPT_COL
call print_string
; your best night — the lives you kept on your finest win,
; read in lamps (no digits). It survives the loop back to
; the title: the go-again hook.
ld hl, $5800 + 11 * 32 + 14
ld b, LIVES
ld a, (best_lives)
ld c, a
.tpip:
ld a, PIP_UNLIT
inc c
dec c
jr z, .tpcold
ld a, PIP_LIT
dec c
.tpcold:
ld (hl), a
inc hl
djnz .tpip
ret
draw_win_screen:
call restore_under
ld hl, win_text
ld b, MSG_ROW
ld c, WIN_COL
call print_string
ld hl, prompt_text
ld b, CONT_ROW
ld c, PROMPT_COL
call print_string
ret
; draw_lose_screen — the whole attribute table goes black: every lamp,
; every wall, every warm cell, gone in one LDIR. Then the words.
draw_lose_screen:
ld hl, $5800
ld de, $5801
ld (hl), %00000000
ld bc, 767
ldir
ld hl, lose_text
ld b, MSG_ROW
ld c, LOSE_COL
call print_string
ld hl, prompt_text
ld b, CONT_ROW
ld c, PROMPT_COL
call print_string
ret
; ----------------------------------------------------------------------------
; clear_bitmap — zero the pixel layer, $4000-$57FF, with the same
; seed-and-cascade LDIR idiom the cobble wash uses.
; ----------------------------------------------------------------------------
clear_bitmap:
ld hl, $4000
ld de, $4001
ld (hl), 0
ld bc, 6143
ldir
ret
; ----------------------------------------------------------------------------
; player_step — the keys become movement. Each direction key edits a
; TARGET position (tcol, trow) — a proposal, not yet a move — so it
; can be vetoed before it becomes real. Then the move commits: leave
; the old cell, take the new one, draw.
; ----------------------------------------------------------------------------
player_step:
; --- propose: the target starts where he stands ---
ld a, (lamp_col)
ld (tcol), a
ld a, (lamp_row)
ld (trow), a
; The held-key gate: the first press steps at once, then one
; step every PLAYER_REPEAT frames. Releasing every direction
; key re-arms the instant first step, so taps stay crisp.
ld bc, KEYS_OP
in a, (c)
cpl
and %00000011
ld e, a
ld bc, KEYS_Q
in a, (c)
cpl
and %00000001
or e
ld e, a
ld bc, KEYS_A
in a, (c)
cpl
and %00000001
or e
jr nz, .held
xor a
ld (player_timer), a
ret
.held:
ld a, (player_timer)
or a
jr z, .stepnow
dec a
ld (player_timer), a
ret
.stepnow:
ld a, PLAYER_REPEAT
ld (player_timer), a
ld bc, KEYS_OP
in a, (c)
bit 1, a ; O — a zero bit is a pressed key
jr z, .pleft
bit 0, a ; P, same half-row
jr z, .pright
ld bc, KEYS_Q
in a, (c)
bit 0, a ; Q
jr z, .pup
ld bc, KEYS_A
in a, (c)
bit 0, a ; A
jr z, .pdown
ret ; nothing held — nothing to do
.pleft:
ld hl, tcol
dec (hl)
jr .pmove
.pright:
ld hl, tcol
inc (hl)
jr .pmove
.pup:
ld hl, trow
dec (hl)
jr .pmove
.pdown:
ld hl, trow
inc (hl)
.pmove:
; The veto: ask the target cell's attribute whether it's wall.
; NZ means brick — the proposal dies here and he stays put.
ld a, (trow)
ld b, a
ld a, (tcol)
ld c, a
call wall_at
ret nz
; and the mirror rule: he cannot step onto the wisp either
ld a, (tcol)
ld hl, draught_col
cp (hl)
jr nz, .pcommit
ld a, (trow)
ld hl, draught_row
cp (hl)
jr nz, .pcommit
call lose_life ; walking into the cold costs the same
ret
.pcommit:
; --- commit: restore, step, save, draw — in that order ---
call restore_under
ld a, (tcol)
ld (lamp_col), a
ld a, (trow)
ld (lamp_row), a
call save_under
; light it where it lives: while he covers the lamp, its truth
; is the buffer — rewrite the saved attribute, and restore will
; paint the lamp back lit when he leaves
ld a, (under_lamp + 8)
cp LAMP_UNLIT
jr nz, .pdrawn
ld a, LAMP_LIT
ld (under_lamp + 8), a
call light_pip
call blip_lit
call warm_walls
.pdrawn:
call draw_lamp
ret
; ----------------------------------------------------------------------------
; fill_ground — the cobble stipple. Not decoration: the stipple is what
; makes ground-state changes visible later, when the game starts
; recolouring these pixels. Rows 1-23 (row 0 is the HUD).
; ----------------------------------------------------------------------------
fill_ground:
ld b, 1 ; rows 1-23 (row 0 is the HUD)
.fgr:
ld c, 0
.fgc:
ld de, cobble_tex
call blit_tex
inc c
ld a, c
cp 32
jr c, .fgc
inc b
ld a, b
cp 24
jr c, .fgr
ret
; fill_walls — brickwork. Driven by the wall attribute bit, so anything
; painted as wall — now or later in the game — gets its brick for free:
; the map itself decides where the brick goes.
fill_walls:
ld b, 1
.fwr:
ld c, 0
.fwc:
push bc
call attr_addr_cr
bit WALL_BIT, (hl)
pop bc
jr z, .fwn
ld de, brick_tex
call blit_tex
.fwn:
inc c
ld a, c
cp 32
jr c, .fwc
inc b
ld a, b
cp 24
jr c, .fwr
ret
; blit_tex — write the 8-byte texture at DE into cell (C, B)'s bitmap.
; scr_addr_cr finds the cell's first pixel row; INC H steps down the
; other seven, 256 bytes apart.
blit_tex:
push bc
call scr_addr_cr
ld b, 8
.bt:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .bt
pop bc
ret
cobble_tex:
defb %10000010
defb %00000000
defb %00001000
defb %00000000
defb %00100001
defb %00000000
defb %00010000
defb %00000000
brick_tex:
; mortar courses with staggered verticals — dusk-lit stone
defb %00001000
defb %00001000
defb %00001000
defb %11111111
defb %10000000
defb %10000000
defb %10000000
defb %11111111
; ----------------------------------------------------------------------------
; manhattan — distance from the draught to cell (C = col, B = row) -> A.
; Grid distance, not straight-line: |dc| + |dr|, the number of steps a
; 4-connected walker needs — the only distance the night knows.
; ----------------------------------------------------------------------------
manhattan:
ld a, (draught_col)
sub c
jp p, .dc
neg
.dc:
ld d, a
ld a, (draught_row)
sub b
jp p, .dr
neg
.dr:
add a, d
ret
; ----------------------------------------------------------------------------
; draught_step — the hunt, generalised. The wisp steps toward the
; NEAREST LIGHT: a lit lamp, or the lamplighter's own flame. Same
; chase, new prey — and still no walls, no vetoes on the way.
; ----------------------------------------------------------------------------
draught_step:
ld a, (draught_timer)
dec a
ld (draught_timer), a
ret nz
ld a, DRAUGHT_SPEED
ld (draught_timer), a
; withdrawing? after a snuff the night carries its prize
; home before hunting again — behaviour is a MODE now, and
; the mode decides what this beat means
ld a, (draught_mode)
or a
jr z, .hunt
ld a, (draught_home_col)
ld hl, draught_col
cp (hl)
jr nz, .whome
ld a, (draught_home_row)
ld hl, draught_row
cp (hl)
jr nz, .whome
xor a ; home — the hunt resumes at once
ld (draught_mode), a
ld a, DRAUGHT_SPEED
ld (draught_timer), a
ret
.whome:
ld a, (draught_home_col)
ld (seek_col), a
ld a, (draught_home_row)
ld (seek_row), a
jp .chase
.hunt:
; the lamplighter's flame is the first candidate...
ld a, (lamp_col)
ld c, a
ld (seek_col), a
ld a, (lamp_row)
ld b, a
ld (seek_row), a
call manhattan
ld (seek_best), a
; ...then every lit lamp, keeping the nearest. The lamp table
; names the candidates; the SCREEN says which are lit — the
; same attribute truth the collision system reads.
ld hl, lamp_data
.scan:
ld a, (hl)
cp $FF
jr z, .chase
ld c, a
inc hl
ld b, (hl)
inc hl
push hl
push bc
call attr_addr_cr
ld a, (hl)
pop bc
cp LAMP_LIT
jr nz, .dnext ; unlit lamps cast no light
call manhattan
ld hl, seek_best
cp (hl)
jr nc, .dnext ; not nearer — keep the current prey
ld (hl), a
ld a, c
ld (seek_col), a
ld a, b
ld (seek_row), a
.dnext:
pop hl
jr .scan
.chase:
; step one cell along the axis with the greater distance
; (ties go sideways) — the night is 4-connected, like the
; lamplighter
ld a, (draught_col)
ld (dtcol), a
ld a, (draught_row)
ld (dtrow), a
ld a, (seek_col)
ld hl, draught_col
sub (hl)
jp p, .absc
neg
.absc:
ld d, a ; D = |dc|
ld a, (seek_row)
ld hl, draught_row
sub (hl)
jp p, .absr
neg
.absr:
cp d ; |dr| vs |dc|
jr z, .tie
jr c, .horiz
jr .vert
.tie:
ld a, d
or a
ret z ; already on the light
jr .horiz
.horiz:
ld a, (seek_col)
ld hl, draught_col
cp (hl)
jr c, .hleft
ld a, (hl)
inc a
ld (dtcol), a
jr .contact
.hleft:
ld a, (hl)
dec a
ld (dtcol), a
jr .contact
.vert:
ld a, (seek_row)
ld hl, draught_row
cp (hl)
jr c, .vup
ld a, (hl)
inc a
ld (dtrow), a
jr .contact
.vup:
ld a, (hl)
dec a
ld (dtrow), a
.contact:
; never step ONTO the lamplighter: adjacent is as close as
; the night comes. Two movers, two buffers — and one cell
; can only ever be under one of them.
ld a, (dtcol)
ld hl, lamp_col
cp (hl)
jr nz, .dmove
ld a, (dtrow)
ld hl, lamp_row
cp (hl)
jr nz, .dmove
call lose_life ; the touch, priced
ret
.dmove:
call restore_draught
ld a, (dtcol)
ld (draught_col), a
ld a, (dtrow)
ld (draught_row), a
call save_draught
; the snuff: while the wisp covers a lit lamp, the lamp's
; truth is ITS buffer — the same saved-under rule that lights
; lamps beneath the lamplighter, run by the villain. Rewrite
; the saved attribute to cold, and the wisp's own restore
; will leave the lamp out as it moves on.
ld a, (under_draught + 8)
cp LAMP_LIT
jr nz, .nosnuff
ld a, LAMP_UNLIT
ld (under_draught + 8), a
call unlight_pip
call warm_walls
ld a, 1 ; the prize is taken — withdraw
ld (draught_mode), a
.nosnuff:
call draw_draught
ret
; paint_buildings — walk the rectangle table: each entry is col, row,
; width, height; $FF ends the list. Every cell inside a rectangle gets
; the WALL attribute — and because fill_walls textures by the wall bit,
; the brickwork arrives without another line of drawing code.
paint_buildings:
ld hl, bldg_data
.pb:
ld a, (hl)
cp $FF
ret z
ld c, a ; col
inc hl
ld b, (hl) ; row
inc hl
ld d, (hl) ; width
inc hl
ld e, (hl) ; height
inc hl
push hl
.pbrow:
push bc
push de
.pbcol:
push bc
push de
call attr_addr_cr
ld (hl), WALL
pop de
pop bc
inc c
dec d
jr nz, .pbcol
pop de
pop bc
inc b
dec e
jr nz, .pbrow
pop hl
jr .pb
bldg_data:
defb 5, 5, 4, 3
defb 23, 5, 4, 3
defb $FF
; ----------------------------------------------------------------------------
; lose_life — the price of the touch: one ember out, and either a
; fresh start or the fall of night.
; ----------------------------------------------------------------------------
lose_life:
ld a, (lives)
dec a
ld (lives), a
ld e, a
ld d, 0
ld hl, LIFE_BASE
add hl, de
ld (hl), COBBLE ; the ember at the new count goes out
ld a, (lives)
or a
jr z, .gone
; a life left: the lamplighter returns to the start cell
call restore_under
ld a, START_COL
ld (lamp_col), a
ld a, START_ROW
ld (lamp_row), a
call save_under
call draw_lamp
; the taking costs the night its reach — the wisp recoils to
; the far corner, so every life buys a whole fresh chase
; (leaving it beside the respawn made a catch strip every
; life in seconds once the draught learnt to hunt)
call restore_draught
ld a, (draught_home_col)
ld (draught_col), a
ld a, (draught_home_row)
ld (draught_row), a
ld a, DRAUGHT_SPEED
ld (draught_timer), a
xor a ; already home — hunt on arrival
ld (draught_mode), a
call save_draught
call draw_draught
ret
.gone:
call draw_lose_screen
call sting_nightfall
ld a, LOCK
ld (input_lock), a
ld a, STATE_LOSE
ld (game_state), a
ret
; ----------------------------------------------------------------------------
; print_string / print_char — the machine's own letters. The Spectrum
; keeps its font in ROM: eight bytes per character, and FONT is chosen
; so that ASCII code x 8 + FONT is the glyph's address. Each character
; is drawn like any cell: attribute first, eight rows down the cell.
; ----------------------------------------------------------------------------
print_string:
.ps:
ld a, (hl)
cp $FF
ret z
push hl
push bc
call print_char
pop bc
pop hl
inc hl
inc c
jr .ps
print_char:
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
ld de, FONT
add hl, de
ex de, hl
push de
call attr_addr_cr
ld (hl), MSG_ATTR
call scr_addr_cr
pop de
ld b, 8
.pc:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .pc
ret
; ----------------------------------------------------------------------------
; light_pip / unlight_pip / draw_pips / draw_lives.
; ----------------------------------------------------------------------------
; light_pip — warm the next pip along and count the lamp. lit_count is
; the index of the pip to light AND the number of lamps lit so far —
; read it for the address, then step it.
light_pip:
ld a, (lit_count)
ld e, a
ld d, 0
inc a
ld (lit_count), a
ld hl, PIP_BASE
add hl, de
ld (hl), PIP_LIT
ret
; unlight_pip — light_pip's mirror: step the count back and cool the
; pip at the new count. The tally can go DOWN now.
unlight_pip:
ld a, (lit_count)
dec a
ld (lit_count), a
ld e, a
ld d, 0
ld hl, PIP_BASE
add hl, de
ld (hl), PIP_UNLIT
ret
; draw_pips — the tally row: one cell per lamp on the HUD ledge, all
; cold to start. A pip is pure attribute — no glyph, just a block of
; PAPER — so the row costs eight bytes of screen and no bitmap at all.
draw_pips:
ld hl, PIP_BASE
ld b, NUM_LAMPS
ld a, PIP_UNLIT
.dp:
ld (hl), a
inc hl
djnz .dp
ret
; draw_lives — three embers on the ledge's right shoulder.
draw_lives:
ld hl, LIFE_BASE
ld b, LIVES
ld a, LIFE_PIP
.dlv:
ld (hl), a
inc hl
djnz .dlv
ret
; ----------------------------------------------------------------------------
; draw_lamps — walk the position table: col, row pairs, $FF to finish.
; Placement is data; the drawing code neither knows nor cares how many
; lamps the town has tonight.
; ----------------------------------------------------------------------------
draw_lamps:
ld hl, lamp_data
.next:
ld a, (hl)
cp $FF
ret z
ld c, a
inc hl
ld b, (hl)
inc hl
push hl
call draw_lantern
pop hl
jr .next
; draw_lantern — an unlit lamp into cell (C, B): cold cyan attribute,
; then the lantern glyph down the cell like any texture.
draw_lantern:
call attr_addr_cr
ld (hl), LAMP_UNLIT
call scr_addr_cr
ld de, lantern
ld b, 8
.dlt:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .dlt
ret
; ----------------------------------------------------------------------------
; scr_addr_cr — HL = bitmap address of cell (C, B)'s first pixel row.
; The row's top two bits pick the third of the screen (H), its bottom
; three become L's top bits, and the column fills L's low five.
; ----------------------------------------------------------------------------
scr_addr_cr:
ld a, b
and %00011000 ; the third (row bits 4-3) ...
or %01000000 ; ... under the screen base $40xx
ld h, a
ld a, b
and %00000111 ; the char row within the third ...
rrca ; ... rotated into bits 7-5
rrca
rrca
or c ; the column in bits 4-0
ld l, a
ret
; attr_addr_cr — HL = attribute address of cell (C, B):
; $5800 + row*32 + col, the row shifted up five times.
attr_addr_cr:
ld a, b
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
add hl, hl
add hl, hl
ld de, $5800
add hl, de
ld a, c
ld e, a
ld d, 0
add hl, de
ret
; wall_at — is cell (C, B) wall? The answer is already on the screen:
; every wall cell's attribute has WALL_BIT set, so one bit-test of
; attribute memory is the whole collision system. NZ = wall.
wall_at:
call attr_addr_cr
bit WALL_BIT, (hl)
ret
; ----------------------------------------------------------------------------
; The lamplighter's save / restore / draw.
; ----------------------------------------------------------------------------
; pos_bc — the lamplighter's cell into (C, B), read fresh from the data.
pos_bc:
ld a, (lamp_row)
ld b, a
ld a, (lamp_col)
ld c, a
ret
; save_under — copy the nine bytes of his cell into the buffer: eight
; bitmap rows, then the attribute. Runs as he ARRIVES, before the
; draw — so the buffer always holds true ground, never him.
save_under:
call pos_bc
call scr_addr_cr
ld de, under_lamp
ld b, 8
.su:
ld a, (hl)
ld (de), a
inc de
inc h
djnz .su
call pos_bc
call attr_addr_cr
ld a, (hl)
ld (under_lamp + 8), a
ret
; restore_under — the same nine bytes back the other way: the ground
; returns exactly as it was. Runs as he LEAVES, while the position
; still points at the old cell.
restore_under:
call pos_bc
call scr_addr_cr
ld de, under_lamp
ld b, 8
.ru:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .ru
call pos_bc
call attr_addr_cr
ld a, (under_lamp + 8)
ld (hl), a
ret
draw_lamp:
; his colour first: the cell's attribute becomes his own —
; bright white on the black, his own light about him
call pos_bc
call attr_addr_cr
ld (hl), LAMP_ATTR
; then his shape, eight bytes down the cell like any texture
call pos_bc
call scr_addr_cr
ld de, lamplighter
ld b, 8
.dl:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .dl
ret
; ----------------------------------------------------------------------------
; The draught's save / restore / draw — the lamplighter's engine, twice.
; Same loops, same nine-byte contract, its own buffer and its own
; position: two movers can share a world but never a buffer.
; ----------------------------------------------------------------------------
dpos_bc:
ld a, (draught_row)
ld b, a
ld a, (draught_col)
ld c, a
ret
save_draught:
call dpos_bc
call scr_addr_cr
ld de, under_draught
ld b, 8
.sd:
ld a, (hl)
ld (de), a
inc de
inc h
djnz .sd
call dpos_bc
call attr_addr_cr
ld a, (hl)
ld (under_draught + 8), a
ret
restore_draught:
call dpos_bc
call scr_addr_cr
ld de, under_draught
ld b, 8
.rd:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .rd
call dpos_bc
call attr_addr_cr
ld a, (under_draught + 8)
ld (hl), a
ret
draw_draught:
call dpos_bc
call attr_addr_cr
ld (hl), DRAUGHT_ATTR
call dpos_bc
call scr_addr_cr
ld de, draught_glyph
ld b, 8
.dd:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .dd
ret
; ----------------------------------------------------------------------------
; Data.
; ----------------------------------------------------------------------------
game_state:
defb STATE_TITLE
input_lock:
defb 0
wall_ramp:
; The square warms in the game's own vocabulary: the stone
; stays dusk-blue; the lamplight catches the mortar first
; (ink white -> yellow), then the whole face glows BRIGHT.
; Never magenta — warmth is yellow here, not red-shifted blue.
defb %00001111 ; dusk stone, white mortar
defb %00001111
defb %00001111
defb %00001110 ; the mortar warms — yellow ink
defb %00001110
defb %00001110
defb %01001110 ; the stone catches the glow — BRIGHT
defb %01001110
defb %01110000 ; all eight lit: the square aglow —
; warm yellow stone, only at the win
lamp_data:
defb 4, 3
defb 27, 3
defb 9, 7
defb 22, 7
defb 6, 15
defb 25, 15
defb 13, 20
defb 18, 20
defb $FF
lamp_col:
defb START_COL
lamp_row:
defb START_ROW
tcol:
defb 0
trow:
defb 0
lit_count:
defb 0
lives:
defb LIVES
best_lives:
defb 0 ; lives kept on the finest win — never reset
draught_col:
defb 28
draught_row:
defb 4
draught_home_col:
defb 28
draught_home_row:
defb 4
draught_mode:
defb 0 ; 0 = hunting, 1 = withdrawing home
draught_timer:
defb 16
player_timer:
defb 0
seek_col:
defb 0
seek_row:
defb 0
seek_best:
defb 0 ; the nearest distance found so far
dtcol:
defb 0
dtrow:
defb 0
under_lamp:
defb 0, 0, 0, 0, 0, 0, 0, 0, 0
under_draught:
defb 0, 0, 0, 0, 0, 0, 0, 0, 0
lamplighter:
defb %00111100
defb %00111100
defb %00011000
defb %01111110
defb %00011000
defb %00011000
defb %00100100
defb %01000010
lantern:
defb %00011000
defb %00100100
defb %01111110
defb %01111110
defb %01011010
defb %01111110
defb %01111110
defb %00111100
draught_glyph:
defb %00000000
defb %00111100
defb %01111110
defb %11111111
defb %11111111
defb %01111110
defb %00111100
defb %00000000
title_text:
defb "GLOAMING"
defb $FF
prompt_text:
defb "PRESS SPACE"
defb $FF
win_text:
defb "THE NIGHT IS HELD"
defb $FF
lose_text:
defb "NIGHT FALLS"
defb $FF
end start
Three details earn their lines. Home is remembered at init (draught_home_col/row) rather than hard-coded at the seek, because a later unit will move home each watch and nothing here will need to change. lose_life’s recoil now reads the same home variables — and clears the mode, so a wisp that was mid-withdrawal when it caught you doesn’t respawn still dreaming of a prize it no longer carries. And the withdraw reuses the chase: the mode only chooses the target; the greater-axis step walks there like it walks everywhere.
But run step 1 a while and a flaw shows. Watch the same moment thirty frames later:
Milestone 2 — the rest
The window has to hold. Give arrival a cost: on reaching home the wisp rests for WREST frames — three quarters of the gather — before the hunt resumes. In play it reads as the night savouring what it took.
Step 2: the rest — the snuff window holds even when home is close
+4-2
| 53 | 53 | START_ROW equ 11 | |
| 54 | 54 | PLAYER_REPEAT equ 6 ; frames between steps while a key is held | |
| 55 | 55 | GATHER equ 120 ; frames the dark gathers before its first step | |
| 56 | + | WREST equ 48 ; frames it rests at home after a withdrawal — | |
| 57 | + | ; the snuff window holds even when home is close | |
| 56 | 58 | | |
| 57 | 59 | KEYS_OP equ $DFFE ; half-row P O I U Y — bits 1 and 0 | |
| 58 | 60 | KEYS_Q equ $FBFE ; half-row Q W E R T — bit 0 is Q | |
| ... | |||
| 718 | 720 | ld hl, draught_row | |
| 719 | 721 | cp (hl) | |
| 720 | 722 | jr nz, .whome | |
| 721 | - | xor a ; home — the hunt resumes at once | |
| 723 | + | xor a ; home — rest, then the hunt resumes | |
| 722 | 724 | ld (draught_mode), a | |
| 723 | - | ld a, DRAUGHT_SPEED | |
| 725 | + | ld a, WREST | |
| 724 | 726 | ld (draught_timer), a | |
| 725 | 727 | ret | |
| 726 | 728 | .whome: |
The complete step 2 program
; The Long Night — Unit 2: It Carries Its Prize Home
; Cumulative build; every step runs on its own. Narrative: the unit page.
; Behaviour needs rhythm, not just rules: hunt, snuff, withdraw, rest.
org 32768
COBBLE equ %00000001 ; PAPER black (0), INK blue (1) — dark ground
WALL equ %00001111 ; PAPER blue (1), INK white (7) — pale stone
WALL_BIT equ 3 ; the attribute bit that says "this is wall"
LAMP_ATTR equ %01000111 ; BRIGHT, PAPER black, INK white — his own light
LAMP_UNLIT equ %00000101 ; cold cyan INK on black PAPER — bit 3
; clear, so a lamp reads as floor
LAMP_LIT equ %01000110 ; BRIGHT yellow INK on black — a held flame
DRAUGHT_ATTR equ %01000101 ; the wisp: BRIGHT cyan on black — cold light
LIVES equ 3
LIFE_PIP equ %01010000 ; a life: BRIGHT red PAPER — a small ember
LIFE_BASE equ $5800 + 28 ; row 0, right of the ledge — three cells
DRAUGHT_SPEED equ 16 ; frames between the wisp's steps
DRAUGHT_COL0 equ 28 ; the corner the dark enters from
DRAUGHT_ROW0 equ 4
PIP_UNLIT equ %00101000 ; a cold pip: cyan PAPER, a solid block
PIP_LIT equ %01110000 ; a warm pip: BRIGHT yellow PAPER
PIP_BASE equ $5800 + 12 ; row 0, column 12 — the HUD ledge,
; eight cells, centred over the square
NUM_LAMPS equ 8
MSG_ATTR equ %01000111 ; message text: bright white on black
MSG_ROW equ 11
LOSE_COL equ 10 ; centres the eleven characters
WIN_COL equ 7 ; centres the seventeen characters
FONT equ $3C00 ; the ROM font, addressed so that
; ASCII x 8 lands on the right glyph
STATE_TITLE equ 0
STATE_PLAY equ 1
STATE_WIN equ 2 ; the night is held — the game is won
STATE_LOSE equ 3 ; night falls — the game is lost
LOCK equ 25 ; input-lock frames after entering a screen
SPEAKER equ %00010000 ; port $FE bit 4 — the beeper's one bit
TITLE_COL equ 12 ; GLOAMING, centred
PROMPT_COL equ 10 ; PRESS SPACE, centred
TITLE_ROW equ 8
PROMPT_ROW equ 14
CONT_ROW equ 16 ; "PRESS SPACE" under a win/lose line
START_COL equ 15 ; where the lamplighter begins
START_ROW equ 11
PLAYER_REPEAT equ 6 ; frames between steps while a key is held
GATHER equ 120 ; frames the dark gathers before its first step
WREST equ 48 ; frames it rests at home after a withdrawal —
; the snuff window holds even when home is close
KEYS_OP equ $DFFE ; half-row P O I U Y — bits 1 and 0
KEYS_Q equ $FBFE ; half-row Q W E R T — bit 0 is Q
KEYS_A equ $FDFE ; half-row A S D F G — bit 0 is A
KEYS_SPACE equ $7FFE ; half-row SPACE SYM M N B — bit 0
start:
; --- the border goes black — the night beyond the square ---
; Port $FE bits 0-2 set the BORDER colour. A = 0 = black.
ld a, 0
out ($FE), a
ld a, STATE_TITLE
ld (game_state), a
call draw_title_screen
im 1
ei
call chime_dusk ; after EI — the rests need the interrupt
main_loop:
halt
; the dispatch: each state names what a frame means — the
; title listens for a beginning, PLAY beats the game forward,
; WIN and LOSE hold the screen exactly as it stands
ld a, (game_state)
cp STATE_TITLE
jr z, .do_title
cp STATE_PLAY
jr z, .do_play
call end_step ; WIN or LOSE — wait for a key, then title
jr main_loop
.do_title:
call title_step
jr main_loop
.do_play:
call play_step
jr main_loop
; ----------------------------------------------------------------------------
; title_step — SPACE starts a fresh game.
; ----------------------------------------------------------------------------
title_step:
ld a, (input_lock)
or a
jr z, .tready
dec a
ld (input_lock), a
ret
.tready:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
ret nz
call init_game
ld a, STATE_PLAY
ld (game_state), a
ret
; ----------------------------------------------------------------------------
; end_step — WIN or LOSE: SPACE returns to the title.
; ----------------------------------------------------------------------------
end_step:
ld a, (input_lock)
or a
jr z, .eready
dec a
ld (input_lock), a
ret
.eready:
ld bc, KEYS_SPACE
in a, (c)
bit 0, a
ret nz
call draw_title_screen
call chime_dusk
ld a, LOCK
ld (input_lock), a
ld a, STATE_TITLE
ld (game_state), a
ret
; play_step — one beat of the game: ask the keyboard.
play_step:
call player_step
; contact can end the game mid-frame — if it did, stop here
ld a, (game_state)
cp STATE_PLAY
ret nz
call draught_step
ld a, (game_state)
cp STATE_PLAY
ret nz
; the win check, at the only beat the count can have changed
ld a, (lit_count)
cp NUM_LAMPS
ret nz
; the night is held — the lives you kept are the score
ld a, (lives)
ld hl, best_lives
cp (hl)
jr c, .nobest
ld (hl), a
.nobest:
call draw_win_screen
call fanfare_held
ld a, LOCK
ld (input_lock), a
ld a, STATE_WIN
ld (game_state), a
ret
; ----------------------------------------------------------------------------
; init_game — everything a fresh night needs, gathered from what was
; the boot sequence. Beginning is a callable thing now.
; ----------------------------------------------------------------------------
init_game:
xor a
ld (lit_count), a
ld a, LIVES
ld (lives), a
; --- place the lamplighter ---
; His position is data. Everything that draws him reads it.
ld a, START_COL
ld (lamp_col), a
ld a, START_ROW
ld (lamp_row), a
; --- and, in the far corner, something else ---
ld a, DRAUGHT_COL0
ld (draught_col), a
ld (draught_home_col), a ; and remember where home is —
ld a, DRAUGHT_ROW0
ld (draught_row), a
ld (draught_home_row), a ; the withdraw will need it
; the dark gathers before its first step — a beat to read
; the square before the hunt begins
ld a, GATHER
ld (draught_timer), a
xor a
ld (player_timer), a
ld (draught_mode), a
; --- wipe the canvas ---
; The bitmap ($4000-$57FF) is the pixel layer; whatever was on
; screen before us still lives there. Zero it so only our
; attribute colours show.
call clear_bitmap
; --- texture the ground ---
; Blit the cobble stipple into every cell's bitmap, rows 1-23.
; The attributes will colour these pixels in a moment.
call fill_ground
; --- wash in the cobbles ---
; Seed the first attribute cell, point DE one cell ahead, and
; let LDIR cascade the byte through all 768 cells.
ld hl, $5800
ld de, $5801
ld (hl), COBBLE
ld bc, 767
ldir
call warm_walls
call paint_buildings
; --- brick the walls ---
; Now that the wall cells are painted, fill_walls can read the
; map back and lay brick wherever the wall bit is set.
call fill_walls
call draw_pips
call draw_lives
call draw_lamps
; save what he is about to stand on, BEFORE the first draw
call save_under
call draw_lamp
call save_draught
call draw_draught
ret
; ----------------------------------------------------------------------------
; warm_walls — the square's edge, one attribute write per cell; the
; colour is no longer a constant but the wall_ramp entry for how many
; lamps are lit. Same painting loop as ever — only where C comes from
; has changed.
; ----------------------------------------------------------------------------
warm_walls:
ld a, (lit_count)
ld e, a
ld d, 0
ld hl, wall_ramp
add hl, de
ld c, (hl) ; the byte every wall cell gets
; the top wall: row 1 is 32 cells in a row from $5820
; (row 0 is kept back — it becomes the HUD later)
ld hl, $5820
ld b, 32
.wt:
ld (hl), c
inc hl
djnz .wt
; the bottom wall: row 23, 32 cells from $5AE0
ld hl, $5AE0
ld b, 32
.wb:
ld (hl), c
inc hl
djnz .wb
; the side walls: column 0 and column 31 of rows 1-23.
; Write the row's first cell, hop 31 cells to its last,
; then step a full row (32) down — 23 times.
ld hl, $5820
ld b, 23
.ws:
ld (hl), c
push hl
ld de, 31
add hl, de
ld (hl), c
pop hl
ld de, 32
add hl, de
djnz .ws
ret
; ----------------------------------------------------------------------------
; The beeper. One bit on port $FE: set it, wait, clear it, wait — a
; square wave by hand. C is the half-period (pitch: bigger is lower),
; B the number of cycles (duration). DI while it sounds: the 50 Hz
; interrupt would stretch random half-periods and buzz the tone.
; ----------------------------------------------------------------------------
beep:
di
.bcyc:
ld a, SPEAKER
out ($FE), a
ld a, c
.bd1:
dec a
jr nz, .bd1
xor a
out ($FE), a
ld a, c
.bd2:
dec a
jr nz, .bd2
djnz .bcyc
ei
ret
blip_lit: ; a rising third — the lamp catches
ld b, $17 ; C6
ld c, $67
call beep
ld b, $28 ; E6
ld c, $51
jp beep
chime_dusk: ; two cold tolls, then the motif far off
ld b, $84 ; A4
ld c, $F7
call beep
ld b, 10
call rest
ld b, $84 ; A4
ld c, $F7
call beep
ld b, 13
call rest
ld b, $92 ; E5
ld c, $A4
call beep
ld b, 4
call rest
ld b, $9D ; C5
ld c, $CF
jp beep
; rest — B frames of silence. Musical time rides the heartbeat: the
; gaps between notes are counted in HALTs, not busy-loops.
rest:
halt
djnz rest
ret
fanfare_held: ; THE NIGHT IS HELD — a rising run
ld b, $83 ; C5
ld c, $CF
call beep
ld b, 3
call rest
ld b, $A5 ; E5
ld c, $A4
call beep
ld b, 3
call rest
ld b, $C4 ; G5
ld c, $8A
call beep
ld b, 3
call rest
ld b, $FF ; C6, held — B only counts to 255,
ld c, $67
call beep
ld b, $FF ; so hold it by sounding it twice
ld c, $67
jp beep
sting_nightfall: ; NIGHT FALLS — two steps down, then dark
ld b, $53 ; E5
ld c, $A4
call beep
ld b, 4
call rest
ld b, $49 ; D5
ld c, $B8
call beep
ld b, 4
call rest
ld b, $DC ; A4, long — the night settles on it
ld c, $F7
jp beep
; ----------------------------------------------------------------------------
; Screens.
; ----------------------------------------------------------------------------
; draw_win_screen — lift the lamplighter off the board (restore his
; cell: the eighth lamp, lit, comes out of the buffer), then say it.
; draw_title_screen — sparse and suggestive: a black void, the name,
; the invitation. Everything else is left to the imagination, which
; is both the aesthetic and the budget.
draw_title_screen:
call clear_bitmap
ld hl, $5800
ld de, $5801
ld (hl), %00000000
ld bc, 767
ldir
ld hl, title_text
ld b, TITLE_ROW
ld c, TITLE_COL
call print_string
ld hl, prompt_text
ld b, PROMPT_ROW
ld c, PROMPT_COL
call print_string
; your best night — the lives you kept on your finest win,
; read in lamps (no digits). It survives the loop back to
; the title: the go-again hook.
ld hl, $5800 + 11 * 32 + 14
ld b, LIVES
ld a, (best_lives)
ld c, a
.tpip:
ld a, PIP_UNLIT
inc c
dec c
jr z, .tpcold
ld a, PIP_LIT
dec c
.tpcold:
ld (hl), a
inc hl
djnz .tpip
ret
draw_win_screen:
call restore_under
ld hl, win_text
ld b, MSG_ROW
ld c, WIN_COL
call print_string
ld hl, prompt_text
ld b, CONT_ROW
ld c, PROMPT_COL
call print_string
ret
; draw_lose_screen — the whole attribute table goes black: every lamp,
; every wall, every warm cell, gone in one LDIR. Then the words.
draw_lose_screen:
ld hl, $5800
ld de, $5801
ld (hl), %00000000
ld bc, 767
ldir
ld hl, lose_text
ld b, MSG_ROW
ld c, LOSE_COL
call print_string
ld hl, prompt_text
ld b, CONT_ROW
ld c, PROMPT_COL
call print_string
ret
; ----------------------------------------------------------------------------
; clear_bitmap — zero the pixel layer, $4000-$57FF, with the same
; seed-and-cascade LDIR idiom the cobble wash uses.
; ----------------------------------------------------------------------------
clear_bitmap:
ld hl, $4000
ld de, $4001
ld (hl), 0
ld bc, 6143
ldir
ret
; ----------------------------------------------------------------------------
; player_step — the keys become movement. Each direction key edits a
; TARGET position (tcol, trow) — a proposal, not yet a move — so it
; can be vetoed before it becomes real. Then the move commits: leave
; the old cell, take the new one, draw.
; ----------------------------------------------------------------------------
player_step:
; --- propose: the target starts where he stands ---
ld a, (lamp_col)
ld (tcol), a
ld a, (lamp_row)
ld (trow), a
; The held-key gate: the first press steps at once, then one
; step every PLAYER_REPEAT frames. Releasing every direction
; key re-arms the instant first step, so taps stay crisp.
ld bc, KEYS_OP
in a, (c)
cpl
and %00000011
ld e, a
ld bc, KEYS_Q
in a, (c)
cpl
and %00000001
or e
ld e, a
ld bc, KEYS_A
in a, (c)
cpl
and %00000001
or e
jr nz, .held
xor a
ld (player_timer), a
ret
.held:
ld a, (player_timer)
or a
jr z, .stepnow
dec a
ld (player_timer), a
ret
.stepnow:
ld a, PLAYER_REPEAT
ld (player_timer), a
ld bc, KEYS_OP
in a, (c)
bit 1, a ; O — a zero bit is a pressed key
jr z, .pleft
bit 0, a ; P, same half-row
jr z, .pright
ld bc, KEYS_Q
in a, (c)
bit 0, a ; Q
jr z, .pup
ld bc, KEYS_A
in a, (c)
bit 0, a ; A
jr z, .pdown
ret ; nothing held — nothing to do
.pleft:
ld hl, tcol
dec (hl)
jr .pmove
.pright:
ld hl, tcol
inc (hl)
jr .pmove
.pup:
ld hl, trow
dec (hl)
jr .pmove
.pdown:
ld hl, trow
inc (hl)
.pmove:
; The veto: ask the target cell's attribute whether it's wall.
; NZ means brick — the proposal dies here and he stays put.
ld a, (trow)
ld b, a
ld a, (tcol)
ld c, a
call wall_at
ret nz
; and the mirror rule: he cannot step onto the wisp either
ld a, (tcol)
ld hl, draught_col
cp (hl)
jr nz, .pcommit
ld a, (trow)
ld hl, draught_row
cp (hl)
jr nz, .pcommit
call lose_life ; walking into the cold costs the same
ret
.pcommit:
; --- commit: restore, step, save, draw — in that order ---
call restore_under
ld a, (tcol)
ld (lamp_col), a
ld a, (trow)
ld (lamp_row), a
call save_under
; light it where it lives: while he covers the lamp, its truth
; is the buffer — rewrite the saved attribute, and restore will
; paint the lamp back lit when he leaves
ld a, (under_lamp + 8)
cp LAMP_UNLIT
jr nz, .pdrawn
ld a, LAMP_LIT
ld (under_lamp + 8), a
call light_pip
call blip_lit
call warm_walls
.pdrawn:
call draw_lamp
ret
; ----------------------------------------------------------------------------
; fill_ground — the cobble stipple. Not decoration: the stipple is what
; makes ground-state changes visible later, when the game starts
; recolouring these pixels. Rows 1-23 (row 0 is the HUD).
; ----------------------------------------------------------------------------
fill_ground:
ld b, 1 ; rows 1-23 (row 0 is the HUD)
.fgr:
ld c, 0
.fgc:
ld de, cobble_tex
call blit_tex
inc c
ld a, c
cp 32
jr c, .fgc
inc b
ld a, b
cp 24
jr c, .fgr
ret
; fill_walls — brickwork. Driven by the wall attribute bit, so anything
; painted as wall — now or later in the game — gets its brick for free:
; the map itself decides where the brick goes.
fill_walls:
ld b, 1
.fwr:
ld c, 0
.fwc:
push bc
call attr_addr_cr
bit WALL_BIT, (hl)
pop bc
jr z, .fwn
ld de, brick_tex
call blit_tex
.fwn:
inc c
ld a, c
cp 32
jr c, .fwc
inc b
ld a, b
cp 24
jr c, .fwr
ret
; blit_tex — write the 8-byte texture at DE into cell (C, B)'s bitmap.
; scr_addr_cr finds the cell's first pixel row; INC H steps down the
; other seven, 256 bytes apart.
blit_tex:
push bc
call scr_addr_cr
ld b, 8
.bt:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .bt
pop bc
ret
cobble_tex:
defb %10000010
defb %00000000
defb %00001000
defb %00000000
defb %00100001
defb %00000000
defb %00010000
defb %00000000
brick_tex:
; mortar courses with staggered verticals — dusk-lit stone
defb %00001000
defb %00001000
defb %00001000
defb %11111111
defb %10000000
defb %10000000
defb %10000000
defb %11111111
; ----------------------------------------------------------------------------
; manhattan — distance from the draught to cell (C = col, B = row) -> A.
; Grid distance, not straight-line: |dc| + |dr|, the number of steps a
; 4-connected walker needs — the only distance the night knows.
; ----------------------------------------------------------------------------
manhattan:
ld a, (draught_col)
sub c
jp p, .dc
neg
.dc:
ld d, a
ld a, (draught_row)
sub b
jp p, .dr
neg
.dr:
add a, d
ret
; ----------------------------------------------------------------------------
; draught_step — the hunt, generalised. The wisp steps toward the
; NEAREST LIGHT: a lit lamp, or the lamplighter's own flame. Same
; chase, new prey — and still no walls, no vetoes on the way.
; ----------------------------------------------------------------------------
draught_step:
ld a, (draught_timer)
dec a
ld (draught_timer), a
ret nz
ld a, DRAUGHT_SPEED
ld (draught_timer), a
; withdrawing? after a snuff the night carries its prize
; home before hunting again — behaviour is a MODE now, and
; the mode decides what this beat means
ld a, (draught_mode)
or a
jr z, .hunt
ld a, (draught_home_col)
ld hl, draught_col
cp (hl)
jr nz, .whome
ld a, (draught_home_row)
ld hl, draught_row
cp (hl)
jr nz, .whome
xor a ; home — rest, then the hunt resumes
ld (draught_mode), a
ld a, WREST
ld (draught_timer), a
ret
.whome:
ld a, (draught_home_col)
ld (seek_col), a
ld a, (draught_home_row)
ld (seek_row), a
jp .chase
.hunt:
; the lamplighter's flame is the first candidate...
ld a, (lamp_col)
ld c, a
ld (seek_col), a
ld a, (lamp_row)
ld b, a
ld (seek_row), a
call manhattan
ld (seek_best), a
; ...then every lit lamp, keeping the nearest. The lamp table
; names the candidates; the SCREEN says which are lit — the
; same attribute truth the collision system reads.
ld hl, lamp_data
.scan:
ld a, (hl)
cp $FF
jr z, .chase
ld c, a
inc hl
ld b, (hl)
inc hl
push hl
push bc
call attr_addr_cr
ld a, (hl)
pop bc
cp LAMP_LIT
jr nz, .dnext ; unlit lamps cast no light
call manhattan
ld hl, seek_best
cp (hl)
jr nc, .dnext ; not nearer — keep the current prey
ld (hl), a
ld a, c
ld (seek_col), a
ld a, b
ld (seek_row), a
.dnext:
pop hl
jr .scan
.chase:
; step one cell along the axis with the greater distance
; (ties go sideways) — the night is 4-connected, like the
; lamplighter
ld a, (draught_col)
ld (dtcol), a
ld a, (draught_row)
ld (dtrow), a
ld a, (seek_col)
ld hl, draught_col
sub (hl)
jp p, .absc
neg
.absc:
ld d, a ; D = |dc|
ld a, (seek_row)
ld hl, draught_row
sub (hl)
jp p, .absr
neg
.absr:
cp d ; |dr| vs |dc|
jr z, .tie
jr c, .horiz
jr .vert
.tie:
ld a, d
or a
ret z ; already on the light
jr .horiz
.horiz:
ld a, (seek_col)
ld hl, draught_col
cp (hl)
jr c, .hleft
ld a, (hl)
inc a
ld (dtcol), a
jr .contact
.hleft:
ld a, (hl)
dec a
ld (dtcol), a
jr .contact
.vert:
ld a, (seek_row)
ld hl, draught_row
cp (hl)
jr c, .vup
ld a, (hl)
inc a
ld (dtrow), a
jr .contact
.vup:
ld a, (hl)
dec a
ld (dtrow), a
.contact:
; never step ONTO the lamplighter: adjacent is as close as
; the night comes. Two movers, two buffers — and one cell
; can only ever be under one of them.
ld a, (dtcol)
ld hl, lamp_col
cp (hl)
jr nz, .dmove
ld a, (dtrow)
ld hl, lamp_row
cp (hl)
jr nz, .dmove
call lose_life ; the touch, priced
ret
.dmove:
call restore_draught
ld a, (dtcol)
ld (draught_col), a
ld a, (dtrow)
ld (draught_row), a
call save_draught
; the snuff: while the wisp covers a lit lamp, the lamp's
; truth is ITS buffer — the same saved-under rule that lights
; lamps beneath the lamplighter, run by the villain. Rewrite
; the saved attribute to cold, and the wisp's own restore
; will leave the lamp out as it moves on.
ld a, (under_draught + 8)
cp LAMP_LIT
jr nz, .nosnuff
ld a, LAMP_UNLIT
ld (under_draught + 8), a
call unlight_pip
call warm_walls
ld a, 1 ; the prize is taken — withdraw
ld (draught_mode), a
.nosnuff:
call draw_draught
ret
; paint_buildings — walk the rectangle table: each entry is col, row,
; width, height; $FF ends the list. Every cell inside a rectangle gets
; the WALL attribute — and because fill_walls textures by the wall bit,
; the brickwork arrives without another line of drawing code.
paint_buildings:
ld hl, bldg_data
.pb:
ld a, (hl)
cp $FF
ret z
ld c, a ; col
inc hl
ld b, (hl) ; row
inc hl
ld d, (hl) ; width
inc hl
ld e, (hl) ; height
inc hl
push hl
.pbrow:
push bc
push de
.pbcol:
push bc
push de
call attr_addr_cr
ld (hl), WALL
pop de
pop bc
inc c
dec d
jr nz, .pbcol
pop de
pop bc
inc b
dec e
jr nz, .pbrow
pop hl
jr .pb
bldg_data:
defb 5, 5, 4, 3
defb 23, 5, 4, 3
defb $FF
; ----------------------------------------------------------------------------
; lose_life — the price of the touch: one ember out, and either a
; fresh start or the fall of night.
; ----------------------------------------------------------------------------
lose_life:
ld a, (lives)
dec a
ld (lives), a
ld e, a
ld d, 0
ld hl, LIFE_BASE
add hl, de
ld (hl), COBBLE ; the ember at the new count goes out
ld a, (lives)
or a
jr z, .gone
; a life left: the lamplighter returns to the start cell
call restore_under
ld a, START_COL
ld (lamp_col), a
ld a, START_ROW
ld (lamp_row), a
call save_under
call draw_lamp
; the taking costs the night its reach — the wisp recoils to
; the far corner, so every life buys a whole fresh chase
; (leaving it beside the respawn made a catch strip every
; life in seconds once the draught learnt to hunt)
call restore_draught
ld a, (draught_home_col)
ld (draught_col), a
ld a, (draught_home_row)
ld (draught_row), a
ld a, DRAUGHT_SPEED
ld (draught_timer), a
xor a ; already home — hunt on arrival
ld (draught_mode), a
call save_draught
call draw_draught
ret
.gone:
call draw_lose_screen
call sting_nightfall
ld a, LOCK
ld (input_lock), a
ld a, STATE_LOSE
ld (game_state), a
ret
; ----------------------------------------------------------------------------
; print_string / print_char — the machine's own letters. The Spectrum
; keeps its font in ROM: eight bytes per character, and FONT is chosen
; so that ASCII code x 8 + FONT is the glyph's address. Each character
; is drawn like any cell: attribute first, eight rows down the cell.
; ----------------------------------------------------------------------------
print_string:
.ps:
ld a, (hl)
cp $FF
ret z
push hl
push bc
call print_char
pop bc
pop hl
inc hl
inc c
jr .ps
print_char:
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
ld de, FONT
add hl, de
ex de, hl
push de
call attr_addr_cr
ld (hl), MSG_ATTR
call scr_addr_cr
pop de
ld b, 8
.pc:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .pc
ret
; ----------------------------------------------------------------------------
; light_pip / unlight_pip / draw_pips / draw_lives.
; ----------------------------------------------------------------------------
; light_pip — warm the next pip along and count the lamp. lit_count is
; the index of the pip to light AND the number of lamps lit so far —
; read it for the address, then step it.
light_pip:
ld a, (lit_count)
ld e, a
ld d, 0
inc a
ld (lit_count), a
ld hl, PIP_BASE
add hl, de
ld (hl), PIP_LIT
ret
; unlight_pip — light_pip's mirror: step the count back and cool the
; pip at the new count. The tally can go DOWN now.
unlight_pip:
ld a, (lit_count)
dec a
ld (lit_count), a
ld e, a
ld d, 0
ld hl, PIP_BASE
add hl, de
ld (hl), PIP_UNLIT
ret
; draw_pips — the tally row: one cell per lamp on the HUD ledge, all
; cold to start. A pip is pure attribute — no glyph, just a block of
; PAPER — so the row costs eight bytes of screen and no bitmap at all.
draw_pips:
ld hl, PIP_BASE
ld b, NUM_LAMPS
ld a, PIP_UNLIT
.dp:
ld (hl), a
inc hl
djnz .dp
ret
; draw_lives — three embers on the ledge's right shoulder.
draw_lives:
ld hl, LIFE_BASE
ld b, LIVES
ld a, LIFE_PIP
.dlv:
ld (hl), a
inc hl
djnz .dlv
ret
; ----------------------------------------------------------------------------
; draw_lamps — walk the position table: col, row pairs, $FF to finish.
; Placement is data; the drawing code neither knows nor cares how many
; lamps the town has tonight.
; ----------------------------------------------------------------------------
draw_lamps:
ld hl, lamp_data
.next:
ld a, (hl)
cp $FF
ret z
ld c, a
inc hl
ld b, (hl)
inc hl
push hl
call draw_lantern
pop hl
jr .next
; draw_lantern — an unlit lamp into cell (C, B): cold cyan attribute,
; then the lantern glyph down the cell like any texture.
draw_lantern:
call attr_addr_cr
ld (hl), LAMP_UNLIT
call scr_addr_cr
ld de, lantern
ld b, 8
.dlt:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .dlt
ret
; ----------------------------------------------------------------------------
; scr_addr_cr — HL = bitmap address of cell (C, B)'s first pixel row.
; The row's top two bits pick the third of the screen (H), its bottom
; three become L's top bits, and the column fills L's low five.
; ----------------------------------------------------------------------------
scr_addr_cr:
ld a, b
and %00011000 ; the third (row bits 4-3) ...
or %01000000 ; ... under the screen base $40xx
ld h, a
ld a, b
and %00000111 ; the char row within the third ...
rrca ; ... rotated into bits 7-5
rrca
rrca
or c ; the column in bits 4-0
ld l, a
ret
; attr_addr_cr — HL = attribute address of cell (C, B):
; $5800 + row*32 + col, the row shifted up five times.
attr_addr_cr:
ld a, b
ld l, a
ld h, 0
add hl, hl
add hl, hl
add hl, hl
add hl, hl
add hl, hl
ld de, $5800
add hl, de
ld a, c
ld e, a
ld d, 0
add hl, de
ret
; wall_at — is cell (C, B) wall? The answer is already on the screen:
; every wall cell's attribute has WALL_BIT set, so one bit-test of
; attribute memory is the whole collision system. NZ = wall.
wall_at:
call attr_addr_cr
bit WALL_BIT, (hl)
ret
; ----------------------------------------------------------------------------
; The lamplighter's save / restore / draw.
; ----------------------------------------------------------------------------
; pos_bc — the lamplighter's cell into (C, B), read fresh from the data.
pos_bc:
ld a, (lamp_row)
ld b, a
ld a, (lamp_col)
ld c, a
ret
; save_under — copy the nine bytes of his cell into the buffer: eight
; bitmap rows, then the attribute. Runs as he ARRIVES, before the
; draw — so the buffer always holds true ground, never him.
save_under:
call pos_bc
call scr_addr_cr
ld de, under_lamp
ld b, 8
.su:
ld a, (hl)
ld (de), a
inc de
inc h
djnz .su
call pos_bc
call attr_addr_cr
ld a, (hl)
ld (under_lamp + 8), a
ret
; restore_under — the same nine bytes back the other way: the ground
; returns exactly as it was. Runs as he LEAVES, while the position
; still points at the old cell.
restore_under:
call pos_bc
call scr_addr_cr
ld de, under_lamp
ld b, 8
.ru:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .ru
call pos_bc
call attr_addr_cr
ld a, (under_lamp + 8)
ld (hl), a
ret
draw_lamp:
; his colour first: the cell's attribute becomes his own —
; bright white on the black, his own light about him
call pos_bc
call attr_addr_cr
ld (hl), LAMP_ATTR
; then his shape, eight bytes down the cell like any texture
call pos_bc
call scr_addr_cr
ld de, lamplighter
ld b, 8
.dl:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .dl
ret
; ----------------------------------------------------------------------------
; The draught's save / restore / draw — the lamplighter's engine, twice.
; Same loops, same nine-byte contract, its own buffer and its own
; position: two movers can share a world but never a buffer.
; ----------------------------------------------------------------------------
dpos_bc:
ld a, (draught_row)
ld b, a
ld a, (draught_col)
ld c, a
ret
save_draught:
call dpos_bc
call scr_addr_cr
ld de, under_draught
ld b, 8
.sd:
ld a, (hl)
ld (de), a
inc de
inc h
djnz .sd
call dpos_bc
call attr_addr_cr
ld a, (hl)
ld (under_draught + 8), a
ret
restore_draught:
call dpos_bc
call scr_addr_cr
ld de, under_draught
ld b, 8
.rd:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .rd
call dpos_bc
call attr_addr_cr
ld a, (under_draught + 8)
ld (hl), a
ret
draw_draught:
call dpos_bc
call attr_addr_cr
ld (hl), DRAUGHT_ATTR
call dpos_bc
call scr_addr_cr
ld de, draught_glyph
ld b, 8
.dd:
ld a, (de)
ld (hl), a
inc de
inc h
djnz .dd
ret
; ----------------------------------------------------------------------------
; Data.
; ----------------------------------------------------------------------------
game_state:
defb STATE_TITLE
input_lock:
defb 0
wall_ramp:
; The square warms in the game's own vocabulary: the stone
; stays dusk-blue; the lamplight catches the mortar first
; (ink white -> yellow), then the whole face glows BRIGHT.
; Never magenta — warmth is yellow here, not red-shifted blue.
defb %00001111 ; dusk stone, white mortar
defb %00001111
defb %00001111
defb %00001110 ; the mortar warms — yellow ink
defb %00001110
defb %00001110
defb %01001110 ; the stone catches the glow — BRIGHT
defb %01001110
defb %01110000 ; all eight lit: the square aglow —
; warm yellow stone, only at the win
lamp_data:
defb 4, 3
defb 27, 3
defb 9, 7
defb 22, 7
defb 6, 15
defb 25, 15
defb 13, 20
defb 18, 20
defb $FF
lamp_col:
defb START_COL
lamp_row:
defb START_ROW
tcol:
defb 0
trow:
defb 0
lit_count:
defb 0
lives:
defb LIVES
best_lives:
defb 0 ; lives kept on the finest win — never reset
draught_col:
defb 28
draught_row:
defb 4
draught_home_col:
defb 28
draught_home_row:
defb 4
draught_mode:
defb 0 ; 0 = hunting, 1 = withdrawing home
draught_timer:
defb 16
player_timer:
defb 0
seek_col:
defb 0
seek_row:
defb 0
seek_best:
defb 0 ; the nearest distance found so far
dtcol:
defb 0
dtrow:
defb 0
under_lamp:
defb 0, 0, 0, 0, 0, 0, 0, 0, 0
under_draught:
defb 0, 0, 0, 0, 0, 0, 0, 0, 0
lamplighter:
defb %00111100
defb %00111100
defb %00011000
defb %01111110
defb %00011000
defb %00011000
defb %00100100
defb %01000010
lantern:
defb %00011000
defb %00100100
defb %01111110
defb %01111110
defb %01011010
defb %01111110
defb %01111110
defb %00111100
draught_glyph:
defb %00000000
defb %00111100
defb %01111110
defb %11111111
defb %11111111
defb %01111110
defb %00111100
defb %00000000
title_text:
defb "GLOAMING"
defb $FF
prompt_text:
defb "PRESS SPACE"
defb $FF
win_text:
defb "THE NIGHT IS HELD"
defb $FF
lose_text:
defb "NIGHT FALLS"
defb $FF
end start
The implementation is one register swap — the arrival loads WREST into the same timer the pace uses, so the rest costs no new machinery at all. The timer was always “frames until this creature next acts”; the rest just makes that number briefly enormous.
When it’s wrong, see why
- It never comes back out. The mode isn’t clearing — the arrival compare must match both coordinates against home before writing 0. Check the pair of
cp (hl)branches. - It jitters at the corner. You’re clearing the mode when near home instead of at it, or the withdraw target and the stored home disagree. Home is two exact bytes; the arrival test is exact equality.
- The rest never happens. The
WRESTload has to replace the pace reload in the arrival path — if the ordinary reload runs afterwards, it overwrites the rest before a single frame of it elapses. - It walks home after catching you.
lose_lifemust cleardraught_mode. The recoil already puts it at home; a set mode makes its first act a zero-length withdrawal — harmless — but a mid-withdraw catch without the clear sends it ambling back across the square, ignoring you completely. - It rests after every single step. You’ve written
WRESTinto the timer in the wrong branch — it belongs only in the just-arrived-home path, not.whome.
Before and after
The rules barely changed — a byte of state, a constant, a longer timer load — but the experience changed species. Pressure now arrives in waves with shape: threat, loss, reprieve, threat. You plan during the withdrawals; you gamble during the rests; you feel the hunt resume in your shoulders. This is the unit’s law, and it generalises to every enemy you will ever build: a behaviour is not a rule, it’s a rhythm of rules. Any creature worth fearing has at least two modes, and the space between them is where the player gets to be clever.
Try this: turn the mercy dial
WREST is the size of your reprieve. At 10 the rest is a rumour and the slog creeps back; at 120 the wisp practically hibernates and the game goes slack. Find the value where you use the window every time and still feel rushed inside it. (The shipped game says 48. Argue with it.)
Try this: scatter on a schedule
For the full Namco: make the wisp withdraw every 500 frames even without a prize — a second timer, same mode flag, home and back. Now the pressure has two interleaved rhythms, yours to learn separately. Notice how much design you just bought with one byte of state and two timers — and notice, when you remove it, whether you miss it. Not every rhythm earns its place; this game shipped without the scheduled scatter, and the next unit is partly about why the theft-driven one is enough.
What you’ve learnt
- Mode flags are behaviour: one byte turns a rule into a repertoire, and the movement machinery underneath never needs to know.
- Separate the want from the walk — the mode chooses a target; the chase is shared by every mode.
- Windows are a designed quantity: the rest constant is player-experience expressed as a number, exactly like
PLAYER_REPEATandGATHERbefore it. - Respawn logic must reset every mode a creature carries — stale state after a dramatic event is where AI bugs breed.
- Menace is rhythm, not throughput: the version that attacks least is the one that frightens most.
What’s next
The night takes; the night withdraws; the night rests. But your light still does nothing except sit in its cells and be stolen. Unit 3 makes the light claim ground — every lit lamp warms a pool of the square around it — and teaches the one discipline that keeps two moving sprites honest while the world recolours itself beneath them.