ref: 7b2515d1e47198322407081dfe57c7ca49f22c5f
dir: /macros/code.asm/
; Syntactic sugar macros lb: MACRO ; r, hi, lo ld \1, ((\2) & $ff) << 8 | ((\3) & $ff) ENDM ln: MACRO ; r, hi, lo ld \1, ((\2) & $f) << 4 | ((\3) & $f) ENDM ; Design patterns jumptable: MACRO ld a, [\2] ld e, a ld d, 0 ld hl, \1 add hl, de add hl, de ld a, [hli] ld h, [hl] ld l, a jp hl ENDM maskbits: MACRO ; masks just enough bits to cover the first argument ; the second argument is an optional shift amount ; e.g. "maskbits 26" becomes "and %00011111" (since 26 - 1 = %00011001) ; and "maskbits 3, 2" becomes "and %00001100" (since "maskbits 3" becomes %00000011) ; example usage in rejection sampling: ; .loop ; call Random ; maskbits 26 ; cp 26 ; jr nc, .loop x = 1 rept 8 if x + 1 < (\1) x = x << 1 | 1 endc endr if _NARG == 2 and x << (\2) else and x endc ENDM calc_sine_wave: MACRO ; input: a = a signed 6-bit value ; output: a = d * sin(a * pi/32) and %111111 cp %100000 jr nc, .negative\@ call .apply\@ ld a, h ret .negative\@ and %011111 call .apply\@ ld a, h xor $ff inc a ret .apply\@ ld e, a ld a, d ld d, 0 if _NARG == 1 ld hl, \1 else ld hl, .sinetable\@ endc add hl, de add hl, de ld e, [hl] inc hl ld d, [hl] ld hl, 0 .multiply\@ ; factor amplitude srl a jr nc, .even\@ add hl, de .even\@ sla e rl d and a jr nz, .multiply\@ ret if _NARG == 0 .sinetable\@ sine_table 32 endc ENDM