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;
; Ullrich von Bassewitz, 31.05.1998
;
; char* itoa (int value, char* s, int radix);
; char* utoa (unsigned value, char* s, int radix);
;
.export _itoa, _utoa
.import addysp1
.import __hextab
.importzp sp, sreg, ptr2, ptr3, tmp1
.rodata
specval:
.byte '-', '3', '2', '7', '6', '8', 0
.code
;
; Common subroutine to pop the parameters and put them into core
;
dopop: sta tmp1 ; will loose high byte
ldy #0
lda (sp),y
sta ptr2
sta ptr3
iny
lda (sp),y
sta ptr2+1
sta ptr3+1
iny
lda (sp),y
sta sreg
iny
lda (sp),y
sta sreg+1
jmp addysp1 ; Bump stack pointer
;
; itoa
;
_itoa: jsr dopop ; pop the arguments
; We must handle $8000 in a special way, since it is the only negative
; number that has no positive 16-bit counterpart
ldy tmp1 ; get radix
cpy #10
bne utoa
cmp #$00
bne L2
cpx #$80
bne L2
ldy #6
L1: lda specval,y ; copy -32768
sta (ptr2),y
dey
bpl L1
jmp L10
; Check if the value is negative. If so, write a - sign and negate the
; number.
L2: lda sreg+1 ; get high byte
bpl utoa
lda #'-'
ldy #0
sta (ptr2),y ; store sign
inc ptr2
bne L3
inc ptr2+1
L3: lda sreg
eor #$FF
clc
adc #$01
sta sreg
lda sreg+1
eor #$FF
adc #$00
sta sreg+1
jmp utoa
;
; utoa
;
_utoa: jsr dopop ; pop the arguments
; Convert to string by dividing and push the result onto the stack
utoa: lda #$00
pha ; sentinel
; Divide sreg/tmp1 -> sreg, remainder in a
L5: ldy #16 ; 16 bit
lda #0 ; remainder
L6: asl sreg
rol sreg+1
rol a
cmp tmp1
bcc L7
sbc tmp1
inc sreg
L7: dey
bne L6
tay ; get remainder into y
lda __hextab,y ; get hex character
pha ; save char value on stack
lda sreg
ora sreg+1
bne L5
; Get the characters from the stack into the string
ldy #0
L9: pla
sta (ptr2),y
beq L10 ; jump if sentinel
iny
bne L9 ; jump always
; Done! Return the target string
L10: lda ptr3
ldx ptr3+1
rts
|
