gbsomething/source/home/math.asm

section "home/math.asm", rom0

bits_swap::
    ld c, $80
    ld b, a
    xor a
.loop
    rrc b
    jr nc, .skip
    or c
.skip
    rrc c
    jr nc, .loop
    ret

; TODO: There was a more optimal way to do this with max 16 iterations
array_index::
; hl: array base
; c: entry size
; a: index
    and a
    ret z
    ld b, 0
.loop
    add hl, bc
    dec a
    jr nz, .loop
    ret

divide::
; a: value
; c: divisor
; Returns:
; b: result
; a: remainder
	ld b, 0
.loop
	inc b
	sub c
	jr nc, .loop
	dec b
	add c
	ret