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44 lines
1.0 KiB
ArmAsm
44 lines
1.0 KiB
ArmAsm
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; 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:
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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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; Both sides of an assignment-expression must be cast to (long)
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; because cc65 functions can't return structures -- yet. Example:
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;
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; #include <stdlib.h>
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; div_t answer;
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;
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; (long)answer = (long)div(-41, +3);
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; printf("The quotient is %d, and the remainder is %d.\n",
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; answer.quot, answer.rem);
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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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sta sreg ; Quotient is in sreg
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stx sreg+1
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lda ptr1 ; Unsigned remainder is in ptr1
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ldx ptr1+1
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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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