remquof.c revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma weak remquof = __remquof
/* INDENT OFF */
/*
* float remquof(float x, float y, int *quo) return remainderf(x,y) and an
* integer pointer quo such that *quo = N mod (2**31), where N is the
* exact integeral part of x/y rounded to nearest even.
*
* remquof call internal fmodquof
*/
#include "libm.h"
#include "libm_synonyms.h"
#include "libm_protos.h"
#include <math.h>
extern float fabsf(float);
static const int
is = (int) 0x80000000,
im = 0x007fffff,
ii = 0x7f800000,
iu = 0x00800000;
static const float zero = 0.0F, half = 0.5F;
/* INDENT ON */
static float
fmodquof(float x, float y, int *quo) {
float w;
int hx, ix, iy, iz, k, ny, nd, m, sq;
hx = *(int *) &x;
ix = hx & 0x7fffffff;
iy = *(int *) &y;
sq = (iy ^ hx) & is; /* sign of x/y */
iy &= 0x7fffffff;
/* purge off exception values */
*quo = 0;
if (ix >= ii || iy > ii || iy == 0) {
w = x * y;
w = w / w;
} else if (ix <= iy) {
if (ix < iy)
w = x; /* return x if |x|<|y| */
else {
*quo = 1 + (sq >> 30);
w = zero * x; /* return sign(x)*0.0 */
}
} else {
/* INDENT OFF */
/*
* scale x,y to "normal" with
* ny = exponent of y
* nd = exponent of x minus exponent of y
*/
/* INDENT ON */
ny = iy >> 23;
k = ix >> 23;
/* special case for subnormal y or x */
if (ny == 0) {
ny = 1;
while (iy < iu) {
ny -= 1;
iy += iy;
}
nd = k - ny;
if (k == 0) {
nd += 1;
while (ix < iu) {
nd -= 1;
ix += ix;
}
} else
ix = iu | (ix & im);
} else {
nd = k - ny;
ix = iu | (ix & im);
iy = iu | (iy & im);
}
/* INDENT OFF */
/* fix point fmod for normalized ix and iy */
/*
* while (nd--) {
* iz = ix - iy;
* if (iz < 0)
* ix = ix + ix;
* else if (iz == 0) {
* *(int *) &w = is & hx;
* return w;
* } else
* ix = iz + iz;
* }
*/
/* INDENT ON */
/* unroll the above loop 4 times to gain performance */
m = 0;
k = nd >> 2;
nd -= (k << 2);
while (k--) {
iz = ix - iy;
if (iz >= 0) {
m += 1;
ix = iz + iz;
} else
ix += ix;
m += m;
iz = ix - iy;
if (iz >= 0) {
m += 1;
ix = iz + iz;
} else
ix += ix;
m += m;
iz = ix - iy;
if (iz >= 0) {
m += 1;
ix = iz + iz;
} else
ix += ix;
m += m;
iz = ix - iy;
if (iz >= 0) {
m += 1;
ix = iz + iz;
} else
ix += ix;
m += m;
if (iz == 0) {
iz = (k << 2) + nd;
if (iz < 32)
m <<= iz;
else
m = 0;
m &= 0x7fffffff;
*quo = sq >= 0 ? m : -m;
*(int *) &w = is & hx;
return (w);
}
}
while (nd--) {
iz = ix - iy;
if (iz >= 0) {
m += 1;
ix = iz + iz;
} else
ix += ix;
m += m;
}
/* end of unrolling */
iz = ix - iy;
if (iz >= 0) {
m += 1;
ix = iz;
}
m &= 0x7fffffff;
*quo = sq >= 0 ? m : -m;
/* convert back to floating value and restore the sign */
if (ix == 0) {
*(int *) &w = is & hx;
return (w);
}
while (ix < iu) {
ix += ix;
ny -= 1;
}
while (ix > (iu + iu)) {
ny += 1;
ix >>= 1;
}
if (ny > 0)
*(int *) &w = (is & hx) | (ix & im) | (ny << 23);
else { /* subnormal output */
k = -ny + 1;
ix >>= k;
*(int *) &w = (is & hx) | ix;
}
}
return (w);
}
float
remquof(float x, float y, int *quo) {
int hx, hy, sx, sq;
float v;
hx = *(int *) &x; /* high word of x */
hy = *(int *) &y; /* high word of y */
sx = hx & is; /* sign of x */
sq = (hx ^ hy) & is; /* sign of x/y */
hx ^= sx; /* |x| */
hy &= 0x7fffffff; /* |y| */
/* purge off exception values: y is 0 or NaN, x is Inf or NaN */
*quo = 0;
if (hx >= ii || hy > ii || hy == 0) {
v = x * y;
return (v / v);
}
y = fabsf(y);
x = fabsf(x);
if (hy <= 0x7f7fffff) {
x = fmodquof(x, y + y, quo);
*quo = ((*quo) & 0x3fffffff) << 1;
}
if (hy < 0x01000000) {
if (x + x > y) {
*quo += 1;
if (x == y)
x = zero;
else
x -= y;
if (x + x >= y) {
x -= y;
*quo += 1;
}
}
} else {
v = half * y;
if (x > v) {
*quo += 1;
if (x == y)
x = zero;
else
x -= y;
if (x >= v) {
x -= y;
*quo += 1;
}
}
}
if (sq != 0)
*quo = -(*quo);
return (sx == 0 ? x : -x);
}