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Diffstat (limited to 'usr/src/lib/libm/common/LD/hypotl.c')
| -rw-r--r-- | usr/src/lib/libm/common/LD/hypotl.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/LD/hypotl.c b/usr/src/lib/libm/common/LD/hypotl.c new file mode 100644 index 0000000000..4303eceb8e --- /dev/null +++ b/usr/src/lib/libm/common/LD/hypotl.c @@ -0,0 +1,147 @@ +/* + * 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. + */ + +#if defined(ELFOBJ) +#pragma weak hypotl = __hypotl +#endif + +/* + * hypotl(x,y) + * Method : + * If z=x*x+y*y has error less than sqrt(2)/2 ulp than sqrt(z) has + * error less than 1 ulp. + * So, compute sqrt(x*x+y*y) with some care as follows: + * Assume x>y>0; + * 1. save and set rounding to round-to-nearest + * 2. if x > 2y use + * x1*x1+(y*y+(x2*(x+x2))) for x*x+y*y + * where x1 = x with lower 32 bits cleared, x2 = x-x1; else + * 3. if x <= 2y use + * t1*y1+((x-y)*(x-y)+(t1*y2+t2*y)) + * where t1 = 2x with lower 64 bits cleared, t2 = 2x-t1, y1= y with + * lower 32 bits cleared, y2 = y-y1. + * + * NOTE: DO NOT remove parenthsis! + * + * Special cases: + * hypot(x,y) is INF if x or y is +INF or -INF; else + * hypot(x,y) is NAN if x or y is NAN. + * + * Accuracy: + * hypot(x,y) returns sqrt(x^2+y^2) with error less than 1 ulps (units + * in the last place) + */ + +#include "libm.h" + +#if defined(__x86) +extern enum fp_direction_type __swap87RD(enum fp_direction_type); + +#define k 0x7fff + +long double +hypotl(long double x, long double y) { + long double t1, t2, y1, y2, w; + int *px = (int *) &x, *py = (int *) &y; + int *pt1 = (int *) &t1, *py1 = (int *) &y1; + enum fp_direction_type rd; + int j, nx, ny, nz; + + px[2] &= 0x7fff; /* clear sign bit and padding bits of x and y */ + py[2] &= 0x7fff; + nx = px[2]; /* biased exponent of x and y */ + ny = py[2]; + if (ny > nx) { + w = x; + x = y; + y = w; + nz = ny; + ny = nx; + nx = nz; + } /* force nx >= ny */ + if (nx - ny >= 66) + return (x + y); /* x / y >= 2**65 */ + if (nx < 0x5ff3 && ny > 0x205b) { /* medium x,y */ + /* save and set RD to Rounding to nearest */ + rd = __swap87RD(fp_nearest); + w = x - y; + if (w > y) { + pt1[2] = px[2]; + pt1[1] = px[1]; + pt1[0] = 0; + t2 = x - t1; + x = sqrtl(t1 * t1 - (y * (-y) - t2 * (x + t1))); + } else { + x += x; + py1[2] = py[2]; + py1[1] = py[1]; + py1[0] = 0; + y2 = y - y1; + pt1[2] = px[2]; + pt1[1] = px[1]; + pt1[0] = 0; + t2 = x - t1; + x = sqrtl(t1 * y1 - (w * (-w) - (t2 * y1 + y2 * x))); + } + if (rd != fp_nearest) + __swap87RD(rd); /* restore rounding mode */ + return (x); + } else { + if (nx == k || ny == k) { /* x or y is INF or NaN */ + /* since nx >= ny; nx is always k within this block */ + if (px[1] == 0x80000000 && px[0] == 0) + return (x); + else if (ny == k && py[1] == 0x80000000 && py[0] == 0) + return (y); + else + return (x + y); + } + if (ny == 0) { + if (y == 0.L || x == 0.L) + return (x + y); + pt1[2] = 0x3fff + 16381; + pt1[1] = 0x80000000; + pt1[0] = 0; + py1[2] = 0x3fff - 16381; + py1[1] = 0x80000000; + py1[0] = 0; + x *= t1; + y *= t1; + return (y1 * hypotl(x, y)); + } + j = nx - 0x3fff; + px[2] -= j; + py[2] -= j; + pt1[2] = nx; + pt1[1] = 0x80000000; + pt1[0] = 0; + return (t1 * hypotl(x, y)); + } +} +#endif |