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77 lines
1.3 KiB
ArmAsm
77 lines
1.3 KiB
ArmAsm
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; Ullrich von Bassewitz, 13.08.1998
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;
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; CC65 runtime: helper stuff for mod/div/mul with long signed ints
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;
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; When negating values, we will ignore the possibility here, that one of the
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; values if $80000000, in which case the negate will fail.
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.export poplsargs, adjlsres
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.import getlop, negeax
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.importzp sreg, tmp1, ptr1, ptr3, ptr4
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poplsargs:
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jsr getlop ; Get the operands
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; Calculate the sign of the result, that is sign(op1) * sign(op2) and
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; remember it.
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lda sreg+1
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eor ptr4+1
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sta tmp1 ; Save it across call
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; Make both operands positive
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lda sreg+1 ; Is the operand negative?
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bpl L1 ; Jump if not
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clc ; Make it positive
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lda ptr1
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eor #$FF
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adc #$01
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sta ptr1
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lda ptr1+1
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eor #$FF
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adc #$00
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sta ptr1+1
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lda sreg
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eor #$FF
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adc #$00
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sta sreg
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lda sreg+1
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eor #$FF
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adc #$00
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sta sreg+1
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L1: lda ptr4+1 ; Is the operand nagative?
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bpl L2 ; Jump if not
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clc ; Make it positive
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lda ptr3
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eor #$FF
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adc #$01
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sta ptr3
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lda ptr3+1
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eor #$FF
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adc #$00
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sta ptr3+1
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lda ptr4
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eor #$FF
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adc #$00
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sta ptr4
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lda ptr4+1
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eor #$FF
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adc #$00
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sta ptr4+1
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L2: rts
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; Adjust the result of a mod/div/mul operation
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adjlsres:
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ldy tmp1 ; Check if we must adjust the sign
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bpl L2
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jmp negeax ; Netage value
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