AMD 250 manual Signed Integer Division, Example Code, 189

25112 Rev. 3.06 September 2005 Software Optimization Guide for AMD64 Processors

printf("; dividend: register other than EAX or memory location\n");

printf("\n");
printf("MOV	EAX, 0%08lXh\n", m);
printf("MUL	dividend\n");
if (s) printf("SHR		EDX, %d\n", s);
printf("\n");

printf("; quotient now in EDX\n");

}

printed_code:

fprintf(stderr, "\n"); exit(0);

return(0);

}

Signed Integer Division

The utility sdiv.exe was compiled using the following code. The utilities provided in this document are for reference only and are not supported by AMD.

Example Code

/* This program determines the algorithm (a), multiplier (m), and shift factor (s) to be used to accomplish *signed* division by a constant divisor. Compile with MSVC.

*/

#include <stdio.h>
typedef unsigned __int64		U64;
typedef unsigned long		U32;
U32	log2(U32 i)
{
	U32 t = 0;
	i = i >> 1;
	while (i) {
	i = i >> 1;
	t++;
	}
	return(t);
}
long e;
U32	res1, res2;
U32	oa, os, om;
U32	d, l, s, m, a, r, t;
U64	m_low, m_high, j, k;

Chapter 8 Integer Optimizations 189