mirror of
https://github.com/cc65/cc65.git
synced 2024-11-19 06:31:31 +00:00
99 lines
1.5 KiB
ArmAsm
99 lines
1.5 KiB
ArmAsm
|
;
|
||
|
|
; Ullrich von Bassewitz, 31.05.1998
|
||
|
|
;
|
||
|
|
; char* strncpy (char* dest, const char* src, unsigned size);
|
||
|
|
;
|
||
|
|
|
||
|
|
.export _strncpy
|
||
|
|
.import popax
|
||
|
|
.importzp ptr1, ptr2, ptr3, tmp1, tmp2
|
||
|
|
|
||
|
|
_strncpy:
|
||
|
|
sta tmp1 ; Save size
|
||
|
|
stx tmp2
|
||
|
|
jsr popax ; get src
|
||
|
|
sta ptr1
|
||
|
|
stx ptr1+1
|
||
|
|
jsr popax ; get dest
|
||
|
|
sta ptr2
|
||
|
|
stx ptr2+1
|
||
|
|
sta ptr3 ; remember for function return
|
||
|
|
stx ptr3+1
|
||
|
|
|
||
|
|
ldy #$00
|
||
|
|
ldx tmp1 ; Low byte of size
|
||
|
|
beq L1
|
||
|
|
|
||
|
|
; Copy the first chunk < 256
|
||
|
|
|
||
|
|
jsr CopyChunk
|
||
|
|
bcs L3 ; Jump if end of string found
|
||
|
|
|
||
|
|
; Copy full 256 byte chunks
|
||
|
|
|
||
|
|
L1: lda tmp2 ; High byte of size
|
||
|
|
beq L3
|
||
|
|
ldx #$00 ; Copy 256 bytes
|
||
|
|
L2: jsr CopyChunk
|
||
|
|
bcs L3
|
||
|
|
dec tmp2
|
||
|
|
bne L2
|
||
|
|
beq L9
|
||
|
|
|
||
|
|
; Fill the remaining space with zeroes. If we come here, the value in X
|
||
|
|
; is the low byte of the fill count, tmp2 holds the high byte. Y is the index
|
||
|
|
; into the target string.
|
||
|
|
|
||
|
|
L3: tax ; Test low byte
|
||
|
|
beq L4
|
||
|
|
jsr FillChunk
|
||
|
|
|
||
|
|
L4: lda tmp2 ; Test high byte
|
||
|
|
beq L9
|
||
|
|
L5: jsr FillChunk
|
||
|
|
dec tmp2
|
||
|
|
bne L5
|
||
|
|
|
||
|
|
; Done - return a pointer to the string
|
||
|
|
|
||
|
|
L9: lda ptr3
|
||
|
|
ldx ptr3+1
|
||
|
|
rts
|
||
|
|
|
||
|
|
|
||
|
|
; -------------------------------------------------------------------
|
||
|
|
; Copy byte count in X from ptr1 to ptr2
|
||
|
|
|
||
|
|
.proc CopyChunk
|
||
|
|
L1: lda (ptr1),y
|
||
|
|
sta (ptr2),y
|
||
|
|
beq L3
|
||
|
|
iny
|
||
|
|
bne L2
|
||
|
|
inc ptr1+1
|
||
|
|
inc ptr2+1
|
||
|
|
L2: dex
|
||
|
|
bne L1
|
||
|
|
clc
|
||
|
|
rts
|
||
|
|
L3: sec
|
||
|
|
rts
|
||
|
|
.endproc
|
||
|
|
|
||
|
|
|
||
|
|
; -------------------------------------------------------------------
|
||
|
|
; Fill byte count in X with zeroes
|
||
|
|
|
||
|
|
.proc FillChunk
|
||
|
|
lda #$00
|
||
|
|
L1: sta (ptr1),y
|
||
|
|
iny
|
||
|
|
bne L2
|
||
|
|
inc ptr1+1
|
||
|
|
L2: dex
|
||
|
|
bne L1
|
||
|
|
rts
|
||
|
|
.endproc
|
||
|
|
|
||
|
|
|