idigitdiv.c

来自「Arithmetic for integers of almost unlimi」· C语言 代码 · 共 53 行

/* idigitdiv.c - inline assembler code for MSVC++6.0 on Intel586 */
/* TPf, Sep 1999 */

#include <iint.h>
#include <idigit.h>

#if !defined(USE_C_DIGITDIV)
DigitType 
DigitDiv(quot, h, l, d)
    DigitType *quot, h, l, d;
 /*
    Suppose:	d>0 and h<d quot=QUOT; return REM; where QUOT, REM are
    defined by: h*2^BitsPerDigit + l == d*QUOT + REM, 2^BitsPerDigit > REM >=
    0
 */
{
__asm
    {
/*	.text
	.align 4
	.globl USCORE(DigitDiv)
USCORE(DigitDiv):*/
				; push	ebx
	mov	ebx, quot	; DWORD PTR 8[esp]
	mov	edx, h		; DWORD PTR 12[esp]
	mov	ecx, d		; DWORD PTR 20[esp]
	cmp	ecx, edx	; compute edx-ecx = h-d
	jbe L2			; jump if carry or zero flag is set
				; i.e. if h <= d
	mov	eax, l		; DWORD PTR 16[esp]
	div	ecx
	mov	DWORD PTR [ebx], eax
	mov	eax, edx
	jmp L3
				; pop	ebx
				; ret
L2:

	mov	eax, edx
	xor	edx, edx
        div	ecx
        mov	eax, DWORD PTR 16[esp]
        div	ecx
        mov	DWORD PTR [ebx], eax
        mov	eax, edx
				; pop	ebx
				; ret
L3:
    }
}

#endif