mirror of
https://github.com/cc65/cc65.git
synced 2024-11-11 01:05:25 +00:00
53dd513176
which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
53 lines
942 B
ArmAsm
53 lines
942 B
ArmAsm
;
|
|
; void* memset (void* ptr, int c, size_t n);
|
|
;
|
|
; Ullrich von Bassewitz, 29.05.1998
|
|
;
|
|
|
|
.export _memset
|
|
.import popax
|
|
.importzp ptr1, ptr2, tmp1, tmp2, tmp3
|
|
|
|
_memset:
|
|
sta tmp1 ; Save n
|
|
stx tmp2
|
|
jsr popax ; Get c
|
|
sta tmp3 ; Save c
|
|
jsr popax ; Get ptr
|
|
sta ptr1
|
|
stx ptr1+1 ; Save work copy
|
|
sta ptr2
|
|
stx ptr2+1 ; Save a copy for the function result
|
|
lda tmp3
|
|
|
|
ldy #0
|
|
ldx tmp2 ; Get high byte of n
|
|
beq L2 ; Jump if zero
|
|
|
|
; Set 256 byte blocks
|
|
|
|
L1: sta (ptr1),y ; Set one byte
|
|
iny
|
|
sta (ptr1),y ; Unroll this a bit to make it faster
|
|
iny
|
|
bne L1
|
|
inc ptr1+1
|
|
dex ; Next 256 byte block
|
|
bne L1 ; Repeat if any
|
|
|
|
; Set the remaining bytes if any
|
|
|
|
L2: ldx tmp1 ; Get the low byte of n
|
|
beq L9 ; Low byte is zero
|
|
|
|
L3: sta (ptr1),y ; Set one byte
|
|
iny
|
|
dex ; Done?
|
|
bne L3
|
|
|
|
L9: lda ptr2 ; Load function result
|
|
ldx ptr2+1
|
|
rts
|
|
|
|
|