divide.c

来自「klibc精简化的c程序库」· C语言 代码 · 共 60 行

#include <stdint.h>
#include <asm/gentrap.h>
#include <asm/pal.h>

#if BITS == 64
typedef uint64_t uint;
typedef int64_t sint;
#else
typedef uint32_t uint;
typedef int32_t sint;
#endif

#ifdef SIGNED
typedef sint xint;
#else
typedef uint xint;
#endif

xint NAME(uint num, uint den)
{
	uint quot = 0, qbit = 1;
	int minus = 0;
	xint v;

	if (den == 0) {
		/* This is really $16, but $16 and $24 are exchanged by a script */
		register unsigned long cause asm("$24") = GEN_INTDIV;
		asm volatile ("call_pal %0"::"i" (PAL_gentrap), "r"(cause));
		return 0;	/* If trap returns... */
	}
#if SIGNED
	if ((sint) (num ^ den) < 0)
		minus = 1;
	if ((sint) num < 0)
		num = -num;
	if ((sint) den < 0)
		den = -den;
#endif

	/* Left-justify denominator and count shift */
	while ((sint) den >= 0) {
		den <<= 1;
		qbit <<= 1;
	}

	while (qbit) {
		if (den <= num) {
			num -= den;
			quot += qbit;
		}
		den >>= 1;
		qbit >>= 1;
	}

	v = (xint) (REM ? num : quot);
	if (minus)
		v = -v;
	return v;
}