mirror of https://github.com/cc65/cc65.git
39 lines
1.1 KiB
ArmAsm
39 lines
1.1 KiB
ArmAsm
; divt.s
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;
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; 2002-10-22, Greg King
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;
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; This signed-division function returns both the quotient and the remainder,
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; in this structure: (quotient in sreg, remainder in AX)
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;
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; typedef struct {
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; int rem, quot;
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; } div_t;
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;
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; div_t __fastcall__ div (int numer, int denom);
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;
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.export _div
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.import tosdivax, negax
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.importzp sreg, ptr1, tmp1
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_div: jsr tosdivax ; Division-operator does most of the work
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ldy sreg ; low byte remainder from sreg
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sta sreg ; store low byte quotient to sreg
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lda sreg+1 ; high byte remainder from sreg
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stx sreg+1 ; store high byte quotient to sreg
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tax ; high byte remainder to x
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tya ; low byte remainder to a
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; Adjust the sign of the remainder.
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; It must be the same as the sign of the dividend.
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;
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bit tmp1 ; Load high-byte of left argument
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bpl Pos ; Jump if sign-of-result is positive
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jmp negax ; Result is negative, adjust the sign
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Pos: rts
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