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48 lines
726 B
ArmAsm
48 lines
726 B
ArmAsm
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; Piotr Fusik, 15.04.2002
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; originally by Ullrich von Bassewitz
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; Integer compare function - used by the compare operators
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;
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.export tosicmp, tosicmp0
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.importzp sp, sreg
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tosicmp0:
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ldx #$00
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tosicmp:
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sta sreg
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stx sreg+1 ; Save ax
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ldy #$00
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lda (sp),y ; Get low byte
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tax
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inc sp ; 5
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bne @L1 ; 3
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inc sp+1 ; (5)
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@L1:
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lda (sp),y ; Get high byte
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inc sp ; 5
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bne @L2 ; 3
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inc sp+1 ; (5)
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; Do the compare.
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@L2: sec
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sbc sreg+1 ; Compare high byte
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bne @L4
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cpx sreg ; Compare low byte
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beq @L3
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adc #$FF ; If the C flag is set then clear the N flag
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ora #$01 ; else set the N flag
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@L3: rts
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@L4: bvc @L3
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eor #$FF ; Fix the N flag if overflow
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ora #$01 ; Clear the Z flag
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rts
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