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Improved memset/memcpy/memmove functions by Christian Krueger.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4200 b7a2c559-68d2-44c3-8de9-860c34a00d81
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uz
2009-09-20 14:32:25 +00:00
parent 2153cc46db
commit 0e91f15ea8
3 changed files with 140 additions and 89 deletions
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90
libsrc/common/memcpy.s
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@@ -1,5 +1,7 @@
;
; Ullrich von Bassewitz, 2003-08-20
; Performance increase (about 20%) by
; Christian Krueger, 2009-09-13
;
; void* __fastcall__ memcpy (void* dest, const void* src, size_t n);
;
@@ -10,61 +12,69 @@
.export _memcpy, memcpy_upwards, memcpy_getparams
.import popax
.importzp ptr1, ptr2, ptr3, tmp1
.importzp sp, ptr1, ptr2, ptr3
; ----------------------------------------------------------------------
_memcpy:
jsr memcpy_getparams
memcpy_upwards:
ldy #0
ldx ptr3 ; Get low counter byte
memcpy_upwards: ; assert Y = 0
ldx ptr3+1 ; Get high byte of n
beq L2 ; Jump if zero
; Copy loop
L1: .repeat 2 ; Unroll this a bit to make it faster...
lda (ptr1),Y ; copy a byte
sta (ptr2),Y
iny
.endrepeat
bne L1
inc ptr1+1
inc ptr2+1
dex ; Next 256 byte block
bne L1 ; Repeat if any
@L1: inx ; Bump low counter byte
beq @L3 ; Jump on overflow
@L2: lda (ptr1),y
sta (ptr2),y
iny
bne @L1
inc ptr1+1 ; Bump pointers
inc ptr2+1
bne @L1 ; Branch always
@L3: inc ptr3+1 ; Bump high counter byte
bne @L2
; the following section could be 10% faster if we were able to copy
; back to front - unfortunately we are forced to copy strict from
; low to high since this function is also used for
; memmove and blocks could be overlapping!
; {
L2: ; assert Y = 0
ldx ptr3 ; Get the low byte of n
beq done ; something to copy
; Done. The low byte of dest is still in ptr2
L3: lda (ptr1),Y ; copy a byte
sta (ptr2),Y
iny
dex
bne L3
done: lda ptr2
ldx tmp1 ; get function result (dest)
rts
; }
done: jmp popax ; Pop ptr and return as result
; ----------------------------------------------------------------------
; Get the parameters from stack as follows:
;
; -(size-1) --> ptr3
; size --> ptr3
; src --> ptr1
; dest --> ptr2
; high(dest) --> tmp1
;
; dest is returned in a/x.
; First argument (dest) will remain on stack and is returned in a/x!
memcpy_getparams:
eor #$FF
sta ptr3
txa
eor #$FF
sta ptr3+1 ; Save -(size-1)
memcpy_getparams: ; IMPORTANT! Function has to leave with Y=0!
sta ptr3
stx ptr3+1 ; save n to ptr3
jsr popax ; src
sta ptr1
stx ptr1+1
jsr popax ; dest
sta ptr2
stx ptr2+1 ; Save work copy
stx tmp1 ; Save for function result
rts
jsr popax
sta ptr1
stx ptr1+1 ; save src to ptr1
; save dest to ptr2
ldy #1 ; (direct stack access is three cycles faster
; (total cycle count with return))
lda (sp),y
tax
stx ptr2+1 ; save high byte of ptr2
dey ; Y = 0
lda (sp),y ; Get ptr2 low
sta ptr2
rts