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30 lines
965 B
ArmAsm
30 lines
965 B
ArmAsm
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; Christian Krueger, 24-May-2018
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; CC65 runtime: division for 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 is $8000, in which case the negate will fail.
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.export tosdiva0, tosdivax
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.import absvaludiv16, negax
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.importzp sp, ptr1, tmp1
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tosdiva0:
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ldx #0
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tosdivax:
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pha ; check if high-bytes indicate
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txa ; different sign, so that we
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ldy #1 ; negate the result after the operation
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eor (sp),y ; eor with lhs high byte
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sta tmp1 ; save post negation indicator to tmp1
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pla ; back to entry accu
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jsr absvaludiv16
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ldx ptr1+1
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lda ptr1
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ldy tmp1 ; fetch indicator
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bmi negate
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rts
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negate: jmp negax
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