mirror of
https://github.com/cc65/cc65.git
synced 2024-12-23 19:29:37 +00:00
74 lines
1.7 KiB
ArmAsm
74 lines
1.7 KiB
ArmAsm
;
|
|
; void* memset (void* ptr, int c, size_t n);
|
|
; void* _bzero (void* ptr, size_t n);
|
|
; void bzero (void* ptr, size_t n);
|
|
;
|
|
; Ullrich von Bassewitz, 29.05.1998
|
|
;
|
|
; NOTE: bzero will return it's first argument as memset does. It is no problem
|
|
; to declare the return value as void, since it may be ignored. _bzero
|
|
; (note the leading underscore) is declared with the proper return type,
|
|
; because the compiler will replace memset by _bzero if the fill value
|
|
; is zero, and the optimizer looks at the return type to see if the value
|
|
; in a/x is of any use.
|
|
;
|
|
|
|
.export _memset, _bzero, __bzero
|
|
.import popax
|
|
.importzp sp, ptr1, ptr2, ptr3, tmp1
|
|
|
|
_bzero:
|
|
__bzero:
|
|
sta ptr3
|
|
stx ptr3+1 ; Save n
|
|
lda #0
|
|
sta tmp1 ; fill with zeros
|
|
beq common
|
|
|
|
_memset:
|
|
sta ptr3 ; Save n
|
|
stx ptr3+1
|
|
jsr popax ; Get c
|
|
sta tmp1 ; Save c
|
|
|
|
; Common stuff for memset and bzero from here
|
|
|
|
common:
|
|
ldy #1
|
|
lda (sp),y
|
|
tax
|
|
dey
|
|
lda (sp),y ; Get ptr
|
|
sta ptr1
|
|
stx ptr1+1 ; Save work copy
|
|
|
|
lda tmp1 ; Load fill value
|
|
ldy #0
|
|
ldx ptr3+1 ; 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 ptr3 ; 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: jmp popax ; Pop ptr and return as result
|
|
|
|
|