diff options
Diffstat (limited to 'usr/src/lib/libm/common/m9x/scalbln.c')
-rw-r--r-- | usr/src/lib/libm/common/m9x/scalbln.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/m9x/scalbln.c b/usr/src/lib/libm/common/m9x/scalbln.c new file mode 100644 index 0000000000..eb11e56a54 --- /dev/null +++ b/usr/src/lib/libm/common/m9x/scalbln.c @@ -0,0 +1,109 @@ +/* + * 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 scalbln = __scalbln +#endif + +#include "libm.h" +#include <float.h> /* DBL_MAX, DBL_MIN */ + +static const double twom54 = 5.5511151231257827021181583404541015625e-17; +#if defined(USE_FPSCALE) || defined(__x86) +static const double two52 = 4503599627370496.0; +#else +/* + * Normalize non-zero subnormal x and return biased exponent of x in [-51,0] + */ +static int +ilogb_biased(unsigned *px) { + int s = 52; + unsigned v = px[HIWORD] & ~0x80000000, w = px[LOWORD], t = v; + + if (t) + s -= 32; + else + t = w; + if (t & 0xffff0000) + s -= 16, t >>= 16; + if (t & 0xff00) + s -= 8, t >>= 8; + if (t & 0xf0) + s -= 4, t >>= 4; + t <<= 1; + s -= (0xffffaa50 >> t) & 0x3; + if (s < 32) { + v = (v << s) | w >> (32 - s); + w <<= s; + } else { + v = w << (s - 32); + w = 0; + } + px[HIWORD] = (px[HIWORD] & 0x80000000) | v; + px[LOWORD] = w; + return (1 - s); +} +#endif /* defined(USE_FPSCALE) */ + +double +scalbln(double x, long n) { + int *px = (int *) &x, ix, k; + + ix = px[HIWORD] & ~0x80000000; + k = ix >> 20; + if (k == 0x7ff) +#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) + return ((px[HIWORD] & 0x80000) != 0 ? x : x + x); + /* assumes sparc-like QNaN */ +#else + return (x + x); +#endif + if ((px[LOWORD] | ix) == 0 || n == 0) + return (x); + if (k == 0) { +#if defined(USE_FPSCALE) || defined(__x86) + x *= two52; + k = ((px[HIWORD] & ~0x80000000) >> 20) - 52; +#else + k = ilogb_biased((unsigned *) px); +#endif + } + k += (int) n; + if (n > 5000 || k > 0x7fe) + return (DBL_MAX * copysign(DBL_MAX, x)); + if (n < -5000 || k <= -54) + return (DBL_MIN * copysign(DBL_MIN, x)); + if (k > 0) { + px[HIWORD] = (px[HIWORD] & ~0x7ff00000) | (k << 20); + return (x); + } + k += 54; + px[HIWORD] = (px[HIWORD] & ~0x7ff00000) | (k << 20); + return (x * twom54); +} |