2017-12-13 21:36:24 -08:00
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; Syntactic sugar macros
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lb: MACRO ; r, hi, lo
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ld \1, (\2 & $ff) << 8 + (\3 & $ff)
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2017-12-28 13:31:16 -08:00
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ENDM
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2017-12-13 21:36:24 -08:00
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ln: MACRO ; r, hi, lo
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ld \1, (\2 & $f) << 4 + (\3 & $f)
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2017-12-28 13:31:16 -08:00
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ENDM
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2017-12-13 21:36:24 -08:00
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ldpixel: MACRO
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if _NARG >= 5
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lb \1, \2 * 8 + \4, \3 * 8 + \5
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else
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lb \1, \2 * 8, \3 * 8
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endc
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2017-12-28 13:31:16 -08:00
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ENDM
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2017-12-13 21:36:24 -08:00
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depixel EQUS "ldpixel de,"
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bcpixel EQUS "ldpixel bc,"
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; Design patterns
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jumptable: MACRO
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ld a, [\2]
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ld e, a
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ld d, 0
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ld hl, \1
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add hl, de
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add hl, de
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ld a, [hli]
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ld h, [hl]
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ld l, a
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jp hl
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2017-12-28 13:31:16 -08:00
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ENDM
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2017-12-13 21:36:24 -08:00
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2017-12-28 04:23:44 -08:00
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maskbits: MACRO
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2018-01-10 08:57:28 -08:00
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; masks just enough bits to cover the argument
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2018-01-16 14:27:50 -08:00
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; e.g. "maskbits 26" becomes "and %00011111" (since 26 - 1 = %00011001)
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2017-12-13 21:36:24 -08:00
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; example usage in rejection sampling:
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; .loop
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; call Random
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2018-02-03 10:26:34 -08:00
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; maskbits 26
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; cp 26
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2017-12-13 21:36:24 -08:00
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; jr nc, .loop
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x = 1
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rept 8
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2018-01-16 14:27:50 -08:00
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if x + 1 < (\1)
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x = x << 1 | 1
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2017-12-24 09:47:30 -08:00
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endc
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2017-12-13 21:36:24 -08:00
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endr
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and x
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2017-12-28 13:31:16 -08:00
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ENDM
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2018-02-03 18:11:55 -08:00
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calc_sine_wave: MACRO
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; input: a = a signed 6-bit value
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; output: a = d * sin(a * pi/32)
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and %111111
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cp %100000
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jr nc, .negative\@
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call .apply\@
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ld a, h
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ret
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.negative\@
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and %011111
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call .apply\@
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ld a, h
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xor $ff
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inc a
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ret
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.apply\@
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ld e, a
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ld a, d
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ld d, 0
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if _NARG == 1
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ld hl, \1
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else
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ld hl, .sinetable\@
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endc
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add hl, de
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add hl, de
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ld e, [hl]
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inc hl
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ld d, [hl]
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ld hl, 0
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.multiply\@ ; factor amplitude
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srl a
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jr nc, .even\@
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add hl, de
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.even\@
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sla e
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rl d
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and a
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jr nz, .multiply\@
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ret
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if _NARG == 0
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.sinetable\@
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sine_table 32
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endc
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ENDM
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