Initial revision

mach/z80/int/atof.s

@@ -0,0 +1,280 @@
+	.data
+! Set of variables
+
+big:	.byte 0
+	.byte 0
+	.byte 0x40
+	.byte 24	! 2^23
+negfrac:.space 1
+negexp:	.space 1
+begzero:
+nd:	.space 2
+fl:	.space 6
+	exp=fl+4
+eexp:	.space 2
+flexp:	.space 4
+exp5:	.space 4
+endzero:
+ten:	.byte 0
+	.byte 0
+	.byte 0x50
+	.byte 4		! 10
+dig:	.byte 0
+	.byte 0
+fildig:	.byte 0		! here a number from 0 to 31 will be converted flt.
+	.byte 7
+bexp:	.space 2
+
+	.text
+atof:			! entry with stringpointer in hl
+			! exit with pointer to float in hl
+	push ix
+	push iy
+	push bc
+	push de
+	push af
+	ld b,1
+1:
+	ld a,(hl)
+	inc hl
+	cp ' '
+	jr z,1b
+	cp '-'
+	jr nz,1f
+	ld b,-1
+	jr 2f
+1:	cp '+'
+	jr z,2f
+	dec hl
+2:	ld a,b
+	ld (negfrac),a
+	xor a
+	ld de,begzero
+	ld b,endzero-begzero
+1:	ld (de),a
+	inc de
+	djnz 1b
+1:	ld a,(hl)
+	inc hl
+	sub '0'
+	jr c,1f
+	cp 10
+	jr nc,1f
+	ld (fildig),a
+	call cmpbigfl
+	jr z,2f
+	call mulandadd
+	jr 3f
+2:	ld de,(exp)
+	inc de
+	ld (exp),de
+3:	ld de,(nd)
+	inc de
+	ld (nd),de
+	jr 1b
+1:	cp '.'-'0'
+	jr nz,4f
+1:	ld a,(hl)
+	inc hl
+	sub '0'
+	jr c,4f
+	cp 10
+	jr nc,4f
+	ld (fildig),a
+	call cmpbigfl
+	jr z,2f
+	call mulandadd
+	ld de,(exp)
+	dec de
+	ld (exp),de
+2:	ld de,(nd)
+	inc de
+	ld (nd),de
+	jr 1b
+4:
+	ld b,1
+	cp 'E'-'0'
+	jr z,1f
+	cp 'e'-'0'
+	jr nz,5f
+1:	ld a,(hl)
+	inc hl
+	cp '+'
+	jr z,1f
+	cp '-'
+	jr nz,2f
+	ld b,-1
+	jr 1f
+2:	dec hl
+1:	ld a,b
+	ld (negexp),a
+	exx
+	xor a
+	ld h,a
+	ld l,a
+	ld b,a
+	ld d,a
+	ld e,a
+	exx
+1:	ld a,(hl)
+	inc hl
+	sub '0'
+	jr c,1f
+	cp 10
+	jr nc,1f
+	exx
+	ld c,a
+	add hl,hl
+	add hl,hl
+	add hl,de
+	add hl,hl
+	add hl,bc
+	ld d,h
+	ld e,l
+	exx
+	jr 1b
+1:	exx
+	ld hl,negexp
+	or a
+	bit 7,(hl)
+	ld hl,(exp)
+	jr z,1f
+	sbc hl,de
+	jr 2f
+1:	add hl,de
+2:	ld (exp),hl
+	exx
+5:	ld a,1
+	ld de,(exp)
+	push de
+	bit 7,d
+	jr z,1f
+	neg
+	ld hl,0
+	or a
+	sbc hl,de
+	ex de,hl
+1:	ld (negexp),a
+	ld (exp),de
+	pop de
+	ld hl,(nd)
+	add hl,de
+	ld de,-33		! -LOGHUGE ?
+	xor a
+	sbc hl,de
+	jp p,1f
+	ld hl,fl
+	ld b,6
+2:	ld (hl),a
+	inc hl
+	djnz 2b
+1:	ld hl,0x0140	! 1.0
+	ld (flexp+2),hl
+	ld hl,0x0350	! 5.0
+	ld (exp5+2),hl
+	ld hl,(exp)
+	ld (bexp),hl
+1:	bit 0,l
+	jr z,2f
+	call xflt
+	.word flexp,exp5,fpmult,4,flexp
+2:	sra h
+	rr l
+	ld a,h
+	or l
+	jr z,3f
+	call xflt
+	.word exp5,exp5,fpmult,4,exp5
+	jr 1b
+3:	ld hl,negexp
+	ld a,(bexp)
+	bit 7,(hl)
+	jr z,1f
+	call xflt
+	.word flexp,fl,fpdiv,4,fl
+	neg
+	jr 2f
+1:	call xflt
+	.word flexp,fl,fpmult,4,fl
+2:	ld b,a
+	ld a,(fl+3)
+	add a,b
+	ld (fl+3),a
+	ld a,(negfrac)
+	bit 7,a
+	jr z,1f
+	call xflt
+	.word fl,fl,fpcomp,4,fl
+1:	call xflt
+	.word fl,fl,fpnorm,4,fl
+	ld hl,fl
+	pop af
+	pop de
+	pop bc
+	pop iy
+	pop ix
+	ret
+
+cmpbigfl:
+	call xflt
+	.word big,fl,fpcmf,0
+	ld a,(fpac+1)
+	bit 7,a
+	ret
+mulandadd:
+	call xflt
+	.word fl,ten,fpmult,4,fl
+	ld a,7
+	ld (fildig+1),a
+	call xflt
+	.word dig,dig,fpnorm,4,dig
+	call xflt
+	.word fl,dig,fpadd,4,fl
+	ret
+
+xflt:
+	ex (sp),iy
+	push af
+	push bc
+	push de
+	push hl
+	ld h,(iy+1)
+	ld l,(iy+0)
+	ld de,fpac
+	ld bc,4
+	ldir
+	ld h,(iy+3)
+	ld l,(iy+2)
+	ld de,fpop
+	ld bc,4
+	ldir
+	push iy
+	ld hl,1f
+	push hl
+	ld h,(iy+5)
+	ld l,(iy+4)
+	jp (hl)
+1:	pop iy
+	ld b,(iy+7)
+	ld c,(iy+6)
+	ld a,b
+	or c
+	jr z,1f
+	inc iy
+	inc iy
+	ld hl,fpac
+	ld d,(iy+7)
+	ld e,(iy+6)
+	ldir
+1:	push iy
+	pop hl
+	ld de,8
+	add hl,de
+	push hl
+	pop iy
+	pop hl
+	pop de
+	pop bc
+	pop af
+	ex (sp),iy
+	ret