gfx_jiffy_game_demo: simplify loop for canvas (SLEEP 1, PEEK every frame)

Co-authored-by: Chris Garrett <chris@chrisg.com>

Author: cursoragent

CHANGELOG.md

@@ -8,11 +8,7 @@
 
 - **Canvas WASM `CHR$(14)` / `CHR$(142)` charset switch**: **`gfx_apply_control_code`** set **`charset_lowercase`** but did not reload **`gfx_load_default_charrom`** (unlike **basic-gfx**, which refreshes ROM each Raylib frame). **`PRINT CHR$(14)`** now reloads glyph bitmaps so **colaburger** and mixed-case text match the CLI.
 
-- **`gfx_jiffy_game_demo.bas`**: **`TEXTAT`** HUD moved to **rows 2–3** (was **22,0** and **22,1**, same rows as the opening **`PRINT`** banner, so **`TI$`/`TI`** looked missing in the IDE).
-
-- **`gfx_jiffy_game_demo.bas`**: **Wait loop** uses **`IF T <= LT`** (not **`T = LT`**) so canvas WASM (**`TI`** from wall ms → 60 Hz buckets) always advances; **`LT = TI - 1`** at start so the first frame isn’t stuck. **`PMOVE`/`ELT`** use **`TI`** at init.
-
-- **`gfx_jiffy_game_demo.bas`** (earlier): Removed **duplicate line numbers** (370, 380 appeared twice; the loader keeps the last line only, so the enemy **EX** update was dropped and **`GOTO 370`** jumped to the wrong block). Renumbered enemy clamp and player sections; **`GOTO 368`** skips enemy math when not time yet.
+- **`gfx_jiffy_game_demo.bas`**: Simplified **main loop** for **canvas WASM** + **basic-gfx**: one **`SLEEP 1`** per frame, **enemy** sine from **`TI`**, **WASD** **`PEEK`** every frame (no **`TI`** bucket wait or **`PMOVE`/`ELT`** gating — those interacted badly with Asyncify / wall-clock **`TI`**). **`TEXTAT`** HUD on **rows 2–3**. Earlier fixes: unique line numbers; **`TEXTAT`** not on banner rows.
 
 - **Examples**: **`gfx_inkey_demo.bas`** uses **`UCASE$(K$)`** before **`ASC`** so lowercase **w** matches **W** (87). **`gfx_key_demo.bas`** REMs clarify **`PEEK(56320+n)`** uses **uppercase ASCII** **`n`** (same as **`ASC("W")`**). **`README.md`** documents polling vs **`INKEY$`** case.
 

examples/gfx_jiffy_game_demo.bas

@@ -1,9 +1,8 @@
 1 REM GFX JIFFY CLOCK DEMO: smooth player + simple enemy motion
 2 REM Run with: ./basic-gfx -petscii examples/gfx_jiffy_game_demo.bas
-3 REM Controls: hold W/A/S/D to move, ESC to quit
-4 REM
-5 REM Uses TI (60Hz) to update at a steady rate regardless of input bursts.
-6 REM Each line number must be unique — duplicate numbers replace earlier lines.
+3 REM Canvas WASM: TI is wall-clock jiffies; use SLEEP 1 + simple loop (no TI bucket wait).
+4 REM Controls: hold W/A/S/D to move, ESC to quit
+5 REM
 10 SCR = 1024
 20 COL = 55296
 30 WIDTH = 40
@@ -14,81 +13,62 @@
 80 PRINT "{CLR}{WHITE}JIFFY CLOCK DEMO  (WASD MOVE, ESC QUITS)"
 90 PRINT "{CYAN}PLAYER IS '@'   ENEMY IS 'X' (SINE WAVE)"
 
-100 REM Player state
+100 REM Player / enemy
 110 PX = 5
 120 PY = 12
 130 PCOL = 1
+140 EX0 = 20
+150 EY = 12
+160 ECOL = 2
+170 AMP = 4
+180 PERIOD = 180
+185 ECH = 160
+190 EX = EX0
 
-140 REM Enemy state (sine wave in X)
-150 EX0 = 20
-160 EY = 12
-170 ECOL = 2
-180 AMP = 4
-190 PERIOD = 180
-195 ECH = 160
-
-200 REM Timing (in jiffies)
-210 REM LT one behind TI so first IF T<=LT passes (canvas TI = wall ms/60Hz)
-220 LT = TI - 1
-230 PSTEP = 3
-235 PMOVE = TI
-240 ESTEP = 6
-245 ELT = TI
-
-250 REM Initial draw
-260 POKE SCR + PY*WIDTH + PX, 0
-270 POKE COL + PY*WIDTH + PX, PCOL
-280 POKE SCR + EY*WIDTH + EX0, ECH
-290 POKE COL + EY*WIDTH + EX0, ECOL
-295 LXE = EX0
+200 REM Initial draw
+210 POKE SCR + PY*WIDTH + PX, 0
+220 POKE COL + PY*WIDTH + PX, PCOL
+230 POKE SCR + EY*WIDTH + EX, ECH
+240 POKE COL + EY*WIDTH + EX, ECOL
+250 LXE = EX
 
 300 REM Main loop
 310 IF PEEK(KEYBASE+27) <> 0 THEN END
 320 T = TI
-330 REM Wait until a new jiffy (TI>T); "=" alone can spin on same bucket
-340 IF T <= LT THEN SLEEP 1 : GOTO 310
-
-350 REM --- Enemy updates at a steady rate (about 10 fps) ---
-355 IF T < ELT + ESTEP THEN GOTO 398
-357 ELT = T
-360 REM Use seconds-ish phase: (T/PERIOD)*2*pi
-370 Q = INT(T / PERIOD)
-380 PH = T - Q * PERIOD
-390 EX = EX0 + INT(AMP * SIN(6.28318 * (PH / PERIOD)))
-392 IF EX < 0 THEN EX = 0
-394 IF EX > 39 THEN EX = 39
-
-396 REM --- Player updates at fixed speed while key held ---
-398 NX = PX : NY = PY
-400 IF T < PMOVE + PSTEP THEN GOTO 500
-420 IF PEEK(KEYBASE+87) <> 0 THEN NY = PY - 1
-430 IF PEEK(KEYBASE+83) <> 0 THEN NY = PY + 1
-440 IF PEEK(KEYBASE+65) <> 0 THEN NX = PX - 1
-450 IF PEEK(KEYBASE+68) <> 0 THEN NX = PX + 1
-460 IF NX < 0 THEN NX = 0
-470 IF NX > 39 THEN NX = 39
-480 PMOVE = T
-500 IF NY < 2 THEN NY = 2
-510 IF NY > 24 THEN NY = 24
+330 SLEEP 1
 
-520 REM --- Redraw only when positions change ---
-530 IF NX <> PX OR NY <> PY THEN POKE SCR + PY*WIDTH + PX, 32
+340 REM Enemy: phase from jiffy clock TI (updates every frame after SLEEP)
+350 Q = INT(T / PERIOD)
+360 PH = T - Q * PERIOD
+370 EX = EX0 + INT(AMP * SIN(6.28318 * (PH / PERIOD)))
+380 IF EX < 0 THEN EX = 0
+390 IF EX > 39 THEN EX = 39
 
-540 IF NX <> PX OR NY <> PY THEN PX = NX : PY = NY
+400 REM Player: read keys every frame (no TI gate — works in canvas + basic-gfx)
+410 NX = PX
+420 NY = PY
+430 IF PEEK(KEYBASE+87) <> 0 THEN NY = PY - 1
+440 IF PEEK(KEYBASE+83) <> 0 THEN NY = PY + 1
+450 IF PEEK(KEYBASE+65) <> 0 THEN NX = PX - 1
+460 IF PEEK(KEYBASE+68) <> 0 THEN NX = PX + 1
+470 IF NX < 0 THEN NX = 0
+480 IF NX > 39 THEN NX = 39
+490 IF NY < 2 THEN NY = 2
+500 IF NY > 24 THEN NY = 24
 
-550 POKE SCR + PY*WIDTH + PX, 0
-560 POKE COL + PY*WIDTH + PX, PCOL
+510 REM Redraw when moved
+520 IF NX <> PX OR NY <> PY THEN POKE SCR + PY*WIDTH + PX, 32
+530 IF NX <> PX OR NY <> PY THEN PX = NX : PY = NY
+540 POKE SCR + PY*WIDTH + PX, 0
+550 POKE COL + PY*WIDTH + PX, PCOL
 
-570 REM Draw enemy first, then clear old to avoid "blank" tear on concurrent render
-580 POKE SCR + EY*WIDTH + EX, ECH
-590 POKE COL + EY*WIDTH + EX, ECOL
-600 IF EX <> LXE THEN POKE SCR + EY*WIDTH + LXE, 32
+560 POKE SCR + EY*WIDTH + EX, ECH
+570 POKE COL + EY*WIDTH + EX, ECOL
+580 IF EX <> LXE THEN POKE SCR + EY*WIDTH + LXE, 32
 
-610 REM HUD: rows 0-1 are the PRINT banner — use row 2-3 or text is hidden
-620 TEXTAT 0,2,"TI$=" + TI$ + "  "
-630 TEXTAT 0,3,"TI=" + STR$(TI) + "    "
+590 REM HUD under banner (rows 2-3)
+600 TEXTAT 0,2,"TI$=" + TI$ + "  "
+610 TEXTAT 0,3,"TI=" + STR$(TI) + "    "
 
-640 REM Save last positions/time and loop
-650 LXE = EX
-660 LT = T
-670 GOTO 310
+620 LXE = EX
+630 GOTO 310