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;
; 2003-08-20, Ullrich von Bassewitz
; 2009-09-13, Christian Krueger -- performance increase (about 20%), 2013-07-25 improved unrolling
; 2015-10-23, Greg King
;
; void* __fastcall__ memmove (void* dest, const void* src, size_t size);
;
; NOTE: This function uses entry points from memcpy!
;
.export _memmove
.import memcpy_getparams, memcpy_upwards, popax
.importzp ptr1, ptr2, ptr3, ptr4, tmp1
.macpack generic
.macpack longbranch
; ----------------------------------------------------------------------
_memmove:
jsr memcpy_getparams
; Check for the copy direction. If dest < src, we must copy upwards (start at
; low addresses and increase pointers), otherwise we must copy downwards
; (start at high addresses and decrease pointers).
cmp ptr1
txa
sbc ptr1+1
jcc memcpy_upwards ; Branch if dest < src (upwards copy)
; Copy downwards. Adjust the pointers to the end of the memory regions.
lda ptr1+1
add ptr3+1
sta ptr1+1
lda ptr2+1
add ptr3+1
sta ptr2+1
; handle fractions of a page size first
ldy ptr3 ; count, low byte
bne @entry ; something to copy?
beq PageSizeCopy ; here like bra...
@copyByte:
lda (ptr1),y
sta (ptr2),y
@entry:
dey
bne @copyByte
lda (ptr1),y ; copy remaining byte
sta (ptr2),y
PageSizeCopy: ; assert Y = 0
ldx ptr3+1 ; number of pages
beq done ; none? -> done
@initBase:
dec ptr1+1 ; adjust base...
dec ptr2+1
dey ; in entry case: 0 -> FF
@copyBytes:
.repeat 3 ; unroll this a bit to make it faster...
lda (ptr1),y ; important: unrolling three times gives a nice
sta (ptr2),y ; 255/3 = 85 loop which ends at 0
dey
.endrepeat
@copyEntry: ; in entry case: 0 -> FF
bne @copyBytes
lda (ptr1),y ; Y = 0, copy last byte
sta (ptr2),y
dex ; one page to copy less
bne @initBase ; still a page to copy?
; Done, return dest
done: jmp popax ; Pop ptr and return as result
|
