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authorEric Andersen <andersen@codepoet.org>2001-11-24 04:17:07 +0000
committerEric Andersen <andersen@codepoet.org>2001-11-24 04:17:07 +0000
commit88e814e997c9bc4fd633583d4d6d4779c5b18cfb (patch)
treef17d860955fd44d9c8e7c13c04cf608fec91d780 /libm/powerpc/s_rint.c
parent6db179c722192f2ec769f264d8c1e721b26b5e17 (diff)
Fix naming so things will actually work
-Erik
Diffstat (limited to 'libm/powerpc/s_rint.c')
-rw-r--r--libm/powerpc/s_rint.c157
1 files changed, 157 insertions, 0 deletions
diff --git a/libm/powerpc/s_rint.c b/libm/powerpc/s_rint.c
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+/*******************************************************************************
+** File: rndint.c
+**
+** Contains: C source code for implementations of floating-point
+** functions which round to integral value or format, as
+** defined in header <fp.h>. In particular, this file
+** contains implementations of functions rint, nearbyint,
+** rinttol, round, roundtol, trunc, modf and modfl. This file
+** targets PowerPC or Power platforms.
+**
+** Written by: A. Sazegari, Apple AltiVec Group
+** Created originally by Jon Okada, Apple Numerics Group
+**
+** Copyright: © 1992-2001 by Apple Computer, Inc., all rights reserved
+**
+** Change History (most recent first):
+**
+** 13 Jul 01 ram replaced --setflm calls with inline assembly
+** 03 Mar 01 ali first port to os x using gcc, added the crucial __setflm
+** definition.
+** 1. removed double_t, put in double for now.
+** 2. removed iclass from nearbyint.
+** 3. removed wrong comments intrunc.
+** 4.
+** 13 May 97 ali made performance improvements in rint, rinttol, roundtol
+** and trunc by folding some of the taligent ideas into this
+** implementation. nearbyint is faster than the one in taligent,
+** rint is more elegant, but slower by %30 than the taligent one.
+** 09 Apr 97 ali deleted modfl and deferred to AuxiliaryDD.c
+** 15 Sep 94 ali Major overhaul and performance improvements of all functions.
+** 20 Jul 94 PAF New faster version
+** 16 Jul 93 ali Added the modfl function.
+** 18 Feb 93 ali Changed the return value of fenv functions
+** feclearexcept and feraiseexcept to their new
+** NCEG X3J11.1/93-001 definitions.
+** 16 Dec 92 JPO Removed __itrunc implementation to a
+** separate file.
+** 15 Dec 92 JPO Added __itrunc implementation and modified
+** rinttol to include conversion from double
+** to long int format. Modified roundtol to
+** call __itrunc.
+** 10 Dec 92 JPO Added modf (double) implementation.
+** 04 Dec 92 JPO First created.
+**
+*******************************************************************************/
+
+#include <limits.h>
+#include <math.h>
+
+#define SET_INVALID 0x01000000UL
+
+typedef union
+ {
+ struct {
+#if defined(__BIG_ENDIAN__)
+ unsigned long int hi;
+ unsigned long int lo;
+#else
+ unsigned long int lo;
+ unsigned long int hi;
+#endif
+ } words;
+ double dbl;
+ } DblInHex;
+
+static const unsigned long int signMask = 0x80000000ul;
+static const double twoTo52 = 4503599627370496.0;
+static const double doubleToLong = 4503603922337792.0; // 2^52
+static const DblInHex Huge = {{ 0x7FF00000, 0x00000000 }};
+static const DblInHex TOWARDZERO = {{ 0x00000000, 0x00000001 }};
+
+/*******************************************************************************
+* *
+* The function rint rounds its double argument to integral value *
+* according to the current rounding direction and returns the result in *
+* double format. This function signals inexact if an ordered return *
+* value is not equal to the operand. *
+* *
+********************************************************************************
+* *
+* This function calls: fabs. *
+* *
+*******************************************************************************/
+
+/*******************************************************************************
+* First, an elegant implementation. *
+********************************************************************************
+*
+*double rint ( double x )
+* {
+* double y;
+*
+* y = twoTo52.fval;
+*
+* if ( fabs ( x ) >= y ) // huge case is exact
+* return x;
+* if ( x < 0 ) y = -y; // negative case
+* y = ( x + y ) - y; // force rounding
+* if ( y == 0.0 ) // zero results mirror sign of x
+* y = copysign ( y, x );
+* return ( y );
+* }
+********************************************************************************
+* Now a bit twidling version that is about %30 faster. *
+*******************************************************************************/
+
+double rint ( double x )
+ {
+ DblInHex argument;
+ register double y;
+ unsigned long int xHead;
+ register long int target;
+
+ argument.dbl = x;
+ xHead = argument.words.hi & 0x7fffffffUL; // xHead <- high half of |x|
+ target = ( argument.words.hi < signMask ); // flags positive sign
+
+ if ( xHead < 0x43300000ul )
+/*******************************************************************************
+* Is |x| < 2.0^52? *
+*******************************************************************************/
+ {
+ if ( xHead < 0x3ff00000ul )
+/*******************************************************************************
+* Is |x| < 1.0? *
+*******************************************************************************/
+ {
+ if ( target )
+ y = ( x + twoTo52 ) - twoTo52; // round at binary point
+ else
+ y = ( x - twoTo52 ) + twoTo52; // round at binary point
+ if ( y == 0.0 )
+ { // fix sign of zero result
+ if ( target )
+ return ( 0.0 );
+ else
+ return ( -0.0 );
+ }
+ return y;
+ }
+
+/*******************************************************************************
+* Is 1.0 < |x| < 2.0^52? *
+*******************************************************************************/
+
+ if ( target )
+ return ( ( x + twoTo52 ) - twoTo52 ); // round at binary pt.
+ else
+ return ( ( x - twoTo52 ) + twoTo52 );
+ }
+
+/*******************************************************************************
+* |x| >= 2.0^52 or x is a NaN. *
+*******************************************************************************/
+ return ( x );
+ }
+