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