div.c

操作系统SunOS 4.1.3版本的源码

#ifndef lint
static char     sccsid[] = "@(#)div.c 1.1 92/07/30 SMI";
#endif

/*
 * Copyright (c) 1988 by Sun Microsystems, Inc.
 */

#include <machine/fpu/fpu_simulator.h>
#include <machine/fpu/globals.h>

void
_fp_div(pfpsd, px, py, pz)
	fp_simd_type	*pfpsd;
	unpacked	*px, *py, *pz;
{
	unsigned	r[4], *y, q, c;
	int		n;

	*pz = *px;

	if (((int)py->fpclass >= (int)fp_quiet) || 
				((int)px->fpclass >= (int)fp_quiet)) {
		if ((int)py->fpclass > (int)px->fpclass) *pz = *py;
		return;
	}

	pz->sign = px->sign ^ py->sign;
	switch (px->fpclass) {
	case fp_quiet:
	case fp_signaling:
		return;
	case fp_zero:
	case fp_infinity:
		if (px->fpclass == py->fpclass) {	/* 0/0 or inf/inf */
			fpu_error_nan(pfpsd, pz);
			pz->fpclass = fp_quiet;
		}
		return;
	case fp_normal:
		switch (py->fpclass) {
		case fp_zero:	/* number/0 */
			fpu_set_exception(pfpsd, fp_division);
			pz->fpclass = fp_infinity;
			return;
		case fp_infinity:	/* number/inf */
			pz->fpclass = fp_zero;
			return;
		}
	}

	/* Now x and y are both normal or subnormal. */

	r[0] = px->significand[0];
	r[1] = px->significand[1];
	r[2] = px->significand[2];
	r[3] = px->significand[3];
	y = py->significand;

	if (fpu_cmpli(r, y, 4) >= 0)
		pz->exponent = px->exponent - py->exponent;
	else
		pz->exponent = px->exponent - py->exponent - 1;

	q=0;
	while (q<0x10000) {	/* generate quo[0] */
		q <<= 1;
		if (fpu_cmpli(r, y, 4) >= 0) {
			q += 1; 	/* if r>y do r-=y and q+=1 */
			c = 0;
			c = fpu_sub3wc(&r[3], r[3], y[3], c);
			c = fpu_sub3wc(&r[2], r[2], y[2], c);
			c = fpu_sub3wc(&r[1], r[1], y[1], c);
			c = fpu_sub3wc(&r[0], r[0], y[0], c);
		}
		r[0] = (r[0]<<1)|((r[1]&0x80000000)>>31);	/* r << 1 */
		r[1] = (r[1]<<1)|((r[2]&0x80000000)>>31);
		r[2] = (r[2]<<1)|((r[3]&0x80000000)>>31);
		r[3] = (r[3]<<1);
	}
	pz->significand[0]=q;
	q=0;			/* generate quo[1] */
	n = 32;
	while (n--) {
		q <<= 1;
		if (fpu_cmpli(r, y, 4) >= 0) {
			q += 1; 	/* if r>y do r-=y and q+=1 */
			c = 0;
			c = fpu_sub3wc(&r[3], r[3], y[3], c);
			c = fpu_sub3wc(&r[2], r[2], y[2], c);
			c = fpu_sub3wc(&r[1], r[1], y[1], c);
			c = fpu_sub3wc(&r[0], r[0], y[0], c);
		}
		r[0] = (r[0]<<1)|((r[1]&0x80000000)>>31);	/* r << 1 */
		r[1] = (r[1]<<1)|((r[2]&0x80000000)>>31);
		r[2] = (r[2]<<1)|((r[3]&0x80000000)>>31);
		r[3] = (r[3]<<1);
	}
	pz->significand[1] = q;
	q=0;			/* generate quo[2] */
	n = 32;
	while (n--) {
		q <<= 1;
		if (fpu_cmpli(r, y, 4) >= 0) {
			q += 1; 	/* if r>y do r-=y and q+=1 */
			c = 0;
			c = fpu_sub3wc(&r[3], r[3], y[3], c);
			c = fpu_sub3wc(&r[2], r[2], y[2], c);
			c = fpu_sub3wc(&r[1], r[1], y[1], c);
			c = fpu_sub3wc(&r[0], r[0], y[0], c);
		}
		r[0] = (r[0]<<1)|((r[1]&0x80000000)>>31);	/* r << 1 */
		r[1] = (r[1]<<1)|((r[2]&0x80000000)>>31);
		r[2] = (r[2]<<1)|((r[3]&0x80000000)>>31);
		r[3] = (r[3]<<1);
	}
	pz->significand[2] = q;
	q=0;			/* generate quo[3] */
	n = 32;
	while (n--) {
		q <<= 1;
		if (fpu_cmpli(r, y, 4) >= 0) {
			q += 1; 	/* if r>y do r-=y and q+=1 */
			c  = 0;
			c = fpu_sub3wc(&r[3], r[3], y[3], c);
			c = fpu_sub3wc(&r[2], r[2], y[2], c);
			c = fpu_sub3wc(&r[1], r[1], y[1], c);
			c = fpu_sub3wc(&r[0], r[0], y[0], c);
		}
		r[0] = (r[0]<<1)|((r[1]&0x80000000)>>31);	/* r << 1 */
		r[1] = (r[1]<<1)|((r[2]&0x80000000)>>31);
		r[2] = (r[2]<<1)|((r[3]&0x80000000)>>31);
		r[3] = (r[3]<<1);
	}
	pz->significand[3] = q;
	if ((r[0]|r[1]|r[2]|r[3])==0) pz->sticky = pz->rounded = 0;
	else {
		pz->sticky = 1;		/* half way case won't occur */
		if (fpu_cmpli(r, y, 4) >= 0) pz->rounded = 1;
	}
}

void
_fp_sqrt(pfpsd, px, pz)
	fp_simd_type	*pfpsd;
	unpacked	*px, *pz;
{				/* *pz gets sqrt(*px) */

	unsigned *x, r, c, q, t[4], s[4];
	*pz = *px;
	switch (px->fpclass) {
	case fp_quiet:
	case fp_signaling:
	case fp_zero:
		return;
	case fp_infinity:
		if (px->sign == 1) {	/* sqrt(-inf) */
			fpu_error_nan(pfpsd, pz);
			pz->fpclass = fp_quiet;
		}
		return;
	case fp_normal:
		if (px->sign == 1) {	/* sqrt(-norm) */
			fpu_error_nan(pfpsd, pz);
			pz->fpclass = fp_quiet;
			return;
		}
	}

	/* Now x is normal. */
	x = px->significand;
	if (px->exponent & 1) {	/*
				 * sqrt(1.f * 2**odd) = sqrt (2.+2f)
				 * 2**(odd-1)/2
				 */
		pz->exponent = (px->exponent - 1) / 2;
		x[0] = (x[0]<<1)|((x[1]&0x80000000)>>31);	/* x<<1 */
		x[1] = (x[1]<<1)|((x[2]&0x80000000)>>31);
		x[2] = (x[2]<<1)|((x[3]&0x80000000)>>31);
		x[3] = (x[3]<<1);
	} else {		/*
				 * sqrt(1.f * 2**even) = sqrt (1.f)
				 * 2**(even)/2
				 */
		pz->exponent = px->exponent / 2;
	}
	s[0]=s[1]=s[2]=s[3]=t[0]=t[1]=t[2]=t[3]=0;
	q = 0;
	r = 0x00010000;
	while (r!=0) {			/* compute sqrt[0] */
		t[0] = s[0]+r;
		if (t[0] <= x[0]) {
			s[0] = t[0]+r;
			x[0] -= t[0];
			q += r;
		}
		x[0] = (x[0]<<1)|((x[1]&0x80000000)>>31);	/* x<<1 */
		x[1] = (x[1]<<1)|((x[2]&0x80000000)>>31);
		x[2] = (x[2]<<1)|((x[3]&0x80000000)>>31);
		x[3] = (x[3]<<1);
		r >>= 1;
	}
	pz->significand[0] = q;
	q = 0;
	r = 0x80000000;
	while (r!=0) {			/* compute sqrt[1] */
		t[1] = s[1]+r;	/* no carry */
		t[0] = s[0];
		if (fpu_cmpli(t, x, 2) <= 0) {
			c = 0;
			c = fpu_add3wc(&s[1], t[1], r, c);
			c = fpu_add3wc(&s[0], t[0], 0, c);
			c = 0;
			c = fpu_sub3wc(&x[1], x[1], t[1], c);
			c = fpu_sub3wc(&x[0], x[0], t[0], c);
			q += r;
		}
		x[0] = (x[0]<<1)|((x[1]&0x80000000)>>31);	/* x<<1 */
		x[1] = (x[1]<<1)|((x[2]&0x80000000)>>31);
		x[2] = (x[2]<<1)|((x[3]&0x80000000)>>31);
		x[3] = (x[3]<<1);
		r >>= 1;
	}
	pz->significand[1] = q;
	q = 0;
	r = 0x80000000;
	while (r!=0) {			/* compute sqrt[2] */
		t[2] = s[2]+r;	/* no carry */
		t[1] = s[1];
		t[0] = s[0];
		if (fpu_cmpli(t, x, 3) <= 0) {
			c = 0;
			c = fpu_add3wc(&s[2], t[2], r, c);
			c = fpu_add3wc(&s[1], t[1], 0, c);
			c = fpu_add3wc(&s[0], t[0], 0, c);
			c = 0;
			c = fpu_sub3wc(&x[2], x[2], t[2], c);
			c = fpu_sub3wc(&x[1], x[1], t[1], c);
			c = fpu_sub3wc(&x[0], x[0], t[0], c);
			q += r;
		}
		x[0] = (x[0]<<1)|((x[1]&0x80000000)>>31);	/* x<<1 */
		x[1] = (x[1]<<1)|((x[2]&0x80000000)>>31);
		x[2] = (x[2]<<1)|((x[3]&0x80000000)>>31);
		x[3] = (x[3]<<1);
		r >>= 1;
	}
	pz->significand[2] = q;
	q = 0;
	r = 0x80000000;
	while (r!=0) {			/* compute sqrt[3] */
		t[3] = s[3]+r;	/* no carry */
		t[2] = s[2];
		t[1] = s[1];
		t[0] = s[0];
		if (fpu_cmpli(t, x, 4) <= 0) {
			c = 0;
			c = fpu_add3wc(&s[3], t[3], r, c);
			c = fpu_add3wc(&s[2], t[2], 0, c);
			c = fpu_add3wc(&s[1], t[1], 0, c);
			c = fpu_add3wc(&s[0], t[0], 0, c);
			c = 0;
			c = fpu_sub3wc(&x[3], x[3], t[3], c);
			c = fpu_sub3wc(&x[2], x[2], t[2], c);
			c = fpu_sub3wc(&x[1], x[1], t[1], c);
			c = fpu_sub3wc(&x[0], x[0], t[0], c);
			q += r;
		}
		x[0] = (x[0]<<1)|((x[1]&0x80000000)>>31);	/* x<<1 */
		x[1] = (x[1]<<1)|((x[2]&0x80000000)>>31);
		x[2] = (x[2]<<1)|((x[3]&0x80000000)>>31);
		x[3] = (x[3]<<1);
		r >>= 1;
	}
	pz->significand[3] = q;
	if ((x[0]|x[1]|x[2]|x[3])==0) {
		pz->sticky = pz->rounded = 0;
	} else {
		pz->sticky = 1;
		if (fpu_cmpli(s, x, 4)<0) pz->rounded=1; else pz->rounded = 0;
	}
}