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49 lines
984 B
ArmAsm
49 lines
984 B
ArmAsm
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; Ullrich von Bassewitz, 07.08.1998
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; CC65 runtime: helper stuff for mod/div/mul with 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 $8000, in which case the negate will fail.
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.export popsargs, adjsres
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.import negax, popax
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.importzp sreg, tmp1, tmp2, ptr4
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popsargs:
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stx tmp1 ; Remember sign
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cpx #0
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bpl L1
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jsr negax ; Negate accumulator
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L1: sta ptr4
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stx ptr4+1 ; Save right operand
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jsr popax
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stx tmp2 ; Remember sign
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cpx #0
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bpl L2
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jsr negax
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L2: sta sreg
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stx sreg+1
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; Calculate the sign of the result, that is sign(op1) * sign(op2)
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lda tmp1
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eor tmp2
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sta tmp2 ; Save it across call
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L3: rts
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; Adjust the result of a mod/div/mul operation
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adjsres:
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; Check if we must adjust the sign
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ldy tmp2
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bpl L3
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jmp negax ; Adjust sign
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