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;
; This file, instead of "common/memmove.s", will be assembled for the pce
; target. This version is smaller and faster because it uses the HuC6280's
; block-copy instructions.
;
; 2003-08-20, Ullrich von Bassewitz
; 2015-10-23, Greg King
;
; void* __fastcall__ memmove (void* dest, const void* src, size_t size);
;
; NOTE: This function uses entry points from "pce/memcpy.s"!
;
.export _memmove
.import memcpy_getparams, memcpy_increment, memcpy_transfer
.importzp ptr1, ptr2, ptr3
.macpack generic
.macpack longbranch
; ----------------------------------------------------------------------
_memmove:
jsr memcpy_getparams
; Check for the copy direction. If dest < src, we must copy downwards (start
; at low addresses, and increase pointers); otherwise, we must copy upwards
; (start at high addresses, and decrease pointers).
cmp ptr1
txa
sbc ptr1+1
jcc memcpy_increment ; Branch if dest < src
; Copy decrementing; adjust the pointers to the end of the memory regions.
lda ptr1
add ptr3
sta ptr1
lda ptr1+1
adc ptr3+1
sta ptr1+1
lda ptr1 ; point to last byte of source
bne @L1
dec ptr1+1
@L1: dec ptr1
lda ptr2
add ptr3
sta ptr2
lda ptr2+1
adc ptr3+1
sta ptr2+1
lda ptr2 ; point to last byte of target
bne @L2
dec ptr2+1
@L2: dec ptr2
ldy #$C3 ; TDD opcode
jmp memcpy_transfer
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