mirror of
https://github.com/cc65/cc65.git
synced 2024-11-18 00:07:21 +00:00
96 lines
2.4 KiB
ArmAsm
96 lines
2.4 KiB
ArmAsm
;
|
|
; void* __fastcall__ memset (void* ptr, int c, size_t n);
|
|
; void* __fastcall__ _bzero (void* ptr, size_t n);
|
|
; void __fastcall__ bzero (void* ptr, size_t n);
|
|
;
|
|
; Ullrich von Bassewitz, 29.05.1998
|
|
; Performance increase (about 20%) by
|
|
; Christian Krueger, 12.09.2009
|
|
;
|
|
; 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
|
|
|
|
_bzero:
|
|
__bzero:
|
|
sta ptr3
|
|
stx ptr3+1 ; Save n
|
|
ldx #0 ; Fill with zeros
|
|
beq common
|
|
|
|
_memset:
|
|
sta ptr3 ; Save n
|
|
stx ptr3+1
|
|
jsr popax ; Get c
|
|
tax
|
|
|
|
; Common stuff for memset and bzero from here
|
|
|
|
common: ; Fill value is in X!
|
|
ldy #1
|
|
lda (sp),y
|
|
sta ptr1+1 ; save high byte of ptr
|
|
dey ; Y = 0
|
|
lda (sp),y ; Get ptr
|
|
sta ptr1
|
|
|
|
lsr ptr3+1 ; divide number of
|
|
ror ptr3 ; bytes by two to increase
|
|
bcc evenCount ; speed (ptr3 = ptr3/2)
|
|
oddCount:
|
|
; y is still 0 here
|
|
txa ; restore fill value
|
|
sta (ptr1),y ; save value and increase
|
|
inc ptr1 ; dest. pointer
|
|
bne evenCount
|
|
inc ptr1+1
|
|
evenCount:
|
|
lda ptr1 ; build second pointer section
|
|
clc
|
|
adc ptr3 ; ptr2 = ptr1 + (length/2) <- ptr3
|
|
sta ptr2
|
|
lda ptr1+1
|
|
adc ptr3+1
|
|
sta ptr2+1
|
|
|
|
txa ; restore fill value
|
|
ldx ptr3+1 ; Get high byte of n
|
|
beq L2 ; Jump if zero
|
|
|
|
; Set 256/512 byte blocks
|
|
; y is still 0 here
|
|
L1: .repeat 2 ; Unroll this a bit to make it faster
|
|
sta (ptr1),y ; Set byte in lower section
|
|
sta (ptr2),y ; Set byte in upper section
|
|
iny
|
|
.endrepeat
|
|
bne L1
|
|
inc ptr1+1
|
|
inc ptr2+1
|
|
dex ; Next 256 byte block
|
|
bne L1 ; Repeat if any
|
|
|
|
; Set the remaining bytes if any
|
|
|
|
L2: ldy ptr3 ; Get the low byte of n
|
|
bne L3 ; something to set?
|
|
jmp popax ; no -> Pop ptr and return as result
|
|
|
|
L3a: sta (ptr1),y ; set bytes in low
|
|
sta (ptr2),y ; and high section
|
|
L3: dey
|
|
bne L3a
|
|
sta (ptr1),y ; Set remaining byte(s)
|
|
sta (ptr2),y
|
|
jmp popax ; Pop ptr and return as result
|
|
|
|
|