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71 lines
1.7 KiB
ArmAsm
71 lines
1.7 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 2003-08-20
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;
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; void* __fastcall__ memcpy (void* dest, const void* src, size_t n);
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;
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; NOTE: This function contains entry points for memmove, which will ressort
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; to memcpy for an upwards copy. Don't change this module without looking
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; at memmove!
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;
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.export _memcpy, memcpy_upwards, memcpy_getparams
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.import popax
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.importzp ptr1, ptr2, ptr3, tmp1
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; ----------------------------------------------------------------------
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_memcpy:
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jsr memcpy_getparams
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memcpy_upwards:
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ldy #0
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ldx ptr3 ; Get low counter byte
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; Copy loop
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@L1: inx ; Bump low counter byte
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beq @L3 ; Jump on overflow
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@L2: lda (ptr1),y
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sta (ptr2),y
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iny
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bne @L1
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inc ptr1+1 ; Bump pointers
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inc ptr2+1
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bne @L1 ; Branch always
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@L3: inc ptr3+1 ; Bump high counter byte
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bne @L2
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; Done. The low byte of dest is still in ptr2
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done: lda ptr2
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ldx tmp1 ; get function result (dest)
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rts
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; ----------------------------------------------------------------------
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; Get the parameters from stack as follows:
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;
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; -(size-1) --> ptr3
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; src --> ptr1
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; dest --> ptr2
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; high(dest) --> tmp1
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;
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; dest is returned in a/x.
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memcpy_getparams:
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eor #$FF
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sta ptr3
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txa
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eor #$FF
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sta ptr3+1 ; Save -(size-1)
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jsr popax ; src
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sta ptr1
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stx ptr1+1
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jsr popax ; dest
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sta ptr2
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stx ptr2+1 ; Save work copy
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stx tmp1 ; Save for function result
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rts
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