mirror of https://github.com/cc65/cc65.git
54 lines
1.0 KiB
ArmAsm
54 lines
1.0 KiB
ArmAsm
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; Ullrich von Bassewitz, 1998-12-09, 2004-11-30
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;
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; void __fastcall__ __swap (void* p, void* q, size_t size);
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;
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.export ___swap
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.import popax, popptr1
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.importzp ptr1, ptr2, ptr3
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___swap: 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) into ptr3
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jsr popax ; Get q
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sta ptr2
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stx ptr2+1
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jsr popptr1 ; Get p
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; Prepare for swap
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; ldy #$00 is guaranteed by popptr1
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; Swap loop
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@L1: inc ptr3 ; Bump counter low byte
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beq @L3 ; Branch on overflow
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@L2: lda (ptr1),y
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tax
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lda (ptr2),y
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sta (ptr1),y
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txa
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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
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inc ptr2+1
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bne @L1 ; Branch always (hopefully)
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; Bump the high counter byte
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@L3: inc ptr3+1
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bne @L2
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; Done
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rts
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