atou24

; This is intended for the eZ80, not the Z80 (it will work, just not as efficiently, and only for 16 bits).
; For a Z80 version, see https://github.com/Zeda/Z80-Optimized-Routines/blob/master/conversion/uitoa_16.z80
;
; This expects to be called in ADL mode.

atou24:
;Inputs:
;   IX points to the base-10 string
;Outputs:
;   IX points to the first non-digit byte
;   HL is the 24-bit number
;       Note that if the input exceeds 24 bits, input%2^24 is returned
;Destroys:
;   AF, BC, DE
;
;Set HL and DE to 0
  or a
  sbc hl,hl
  ex de,hl
  sbc hl,hl
  jr .loop_start
.loop:
  inc ix

; multiply HL by 10
  push hl
  pop bc
  add hl,hl
  add hl,hl
  add hl,bc
  add hl,hl

; Now add in the digit
  ld e,a
  add hl,de

.loop_start
  ld a,(ix)
  sub '0'
  cp 10
  jr c,.loop
  ret