6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2026-04-26 13:18:31 +00:00
Code Issues Projects Releases Wiki Activity

Improved memset/memcpy/memmove functions by Christian Krueger.

Browse Source 
git-svn-id: svn://svn.cc65.org/cc65/trunk@4200 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz
2009-09-20 14:32:25 +00:00
parent 2153cc46db
commit 0e91f15ea8
3 changed files with 140 additions and 89 deletions
Download Patch File Download Diff File Expand all files Collapse all files
libsrc/common/memset.s
+50 -26
View File
@@ -1,9 +1,11 @@
;
; void* memset (void* ptr, int c, size_t n);
; void* _bzero (void* ptr, size_t n);
; void bzero (void* ptr, size_t n);
; 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
@@ -15,57 +17,79 @@
.export _memset, _bzero, __bzero
.import popax
.importzp sp, ptr1, ptr2, ptr3, tmp1
.importzp sp, ptr1, ptr2, ptr3
_bzero:
__bzero:
sta ptr3
stx ptr3+1 ; Save n
lda #0 ; Fill with zeros
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: sta tmp1 ; Save the fill value
ldy #1
common: ; Fill value is in X!
ldy #1
lda (sp),y
tax
dey
sta ptr1+1 ; save high byte of ptr
dey ; Y = 0
lda (sp),y ; Get ptr
sta ptr1
stx ptr1+1 ; Save work copy
lda tmp1 ; Load fill value
ldy #0
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 byte blocks
; 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 one byte
iny
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: 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
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