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Fixed an error and improved the code

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git-svn-id: svn://svn.cc65.org/cc65/trunk@3317 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz 2004-11-30 18:47:25 +00:00
parent e506719f43
commit 08074a2ee3
1 changed files with 34 additions and 41 deletions
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75
libsrc/common/_swap.s
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@ -1,62 +1,55 @@
;
; Ullrich von Bassewitz, 09.12.1998
; Ullrich von Bassewitz, 1998-12-09, 2004-11-30
;
; void __fastcall__ _swap (void* p, void* q, size_t size);
;
.export __swap
.import popax
.importzp ptr1, ptr2, ptr3
.export __swap
.import popax
.importzp ptr1, ptr2, ptr3
__swap: sta ptr3 ; Save size
stx ptr3+1
__swap: eor #$FF
sta ptr3
txa
eor #$FF
sta ptr3+1 ; Save -(size+1) into ptr3
jsr popax ; Get q
sta ptr2
stx ptr2+1
jsr popax ; Get q
sta ptr2
stx ptr2+1
jsr popax ; Get p
sta ptr1
stx ptr1+1
jsr popax ; Get p
sta ptr1
stx ptr1+1
; Prepare for swap
ldy #$00
ldy #$00
; Swap 256 byte blocks
; Swap loop
ldx ptr3+1
beq @L2
@L1: inc ptr3 ; Bump counter low byte
beq @L3 ; Branch on overflow
@L1: lda (ptr1),y
tax
lda (ptr2),y
sta (ptr1),y
txa
sta (ptr2),y
iny
bne @L1
dec ptr3+1
bne @L1
@L2: lda (ptr1),y
tax
lda (ptr2),y
sta (ptr1),y
txa
sta (ptr2),y
iny
bne @L1
inc ptr1+1
inc ptr2+1
bne @L1 ; Branch always (hopefully)
; Swap remaining bytes (Y is zero)
; Bump the high counter byte
@L2: ldx ptr3
beq @L9
@L3: lda (ptr1),y
tax
lda (ptr2),y
sta (ptr1),y
txa
sta (ptr2),y
iny
dec ptr3
bne @L3
@L3: inc ptr3+1
bne @L2
; Done
@L9: rts
rts