From 26d7ea91124a9405dff7755a78cfb6232dd15d80 Mon Sep 17 00:00:00 2001 From: Eric Andersen Date: Sat, 24 Nov 2001 03:46:25 +0000 Subject: Move powerpc specific optimizations (courtesy of apple) to powerpc subdir. Put together a theoretical framework for adding arch specific optimizations. Havn't tried this yet but it looks correct... -Erik --- libm/powerpc/frexpldexp.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 libm/powerpc/frexpldexp.c (limited to 'libm/powerpc/frexpldexp.c') diff --git a/libm/powerpc/frexpldexp.c b/libm/powerpc/frexpldexp.c new file mode 100644 index 000000000..6b759f91b --- /dev/null +++ b/libm/powerpc/frexpldexp.c @@ -0,0 +1,72 @@ +/******************************************************************************* +* * +* File frexpldexp.c, * +* Functions frexp(x) and ldexp(x), * +* Implementation of frexp and ldexp functions for the PowerPC. * +* * +* Copyright © 1991 Apple Computer, Inc. All rights reserved. * +* * +* Written by Ali Sazegari, started on January 1991, * +* * +* W A R N I N G: This routine expects a 64 bit double model. * +* * +* December03 1992: first rs6000 implementation. * +* October 05 1993: added special cases for NaN and ° in frexp. * +* May 27 1997: improved the performance of frexp by eliminating the * +* switch statement. * +* June 13 2001: (ram) rewrote frexp to eliminate calls to scalb and * +* logb. * +* * +*******************************************************************************/ + +#include +#include + +static const double two54 = 1.80143985094819840000e+16; /* 0x43500000, 0x00000000 */ + +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; + +double ldexp ( double value, int exp ) + { + if ( exp > SHRT_MAX ) + exp = SHRT_MAX; + else if ( exp < -SHRT_MAX ) + exp = -SHRT_MAX; + return scalb ( value, exp ); + } + +double frexp ( double value, int *eptr ) + { + DblInHex argument; + unsigned long int valueHead; + + argument.dbl = value; + valueHead = argument.words.hi & 0x7fffffffUL; // valueHead <- |x| + + *eptr = 0; + if ( valueHead >= 0x7ff00000 || ( valueHead | argument.words.lo ) == 0 ) + return value; // 0, inf, or NaN + + if ( valueHead < 0x00100000 ) + { // denorm + argument.dbl = two54 * value; + valueHead = argument.words.hi &0x7fffffff; + *eptr = -54; + } + *eptr += ( valueHead >> 20 ) - 1022; + argument.words.hi = ( argument.words.hi & 0x800fffff ) | 0x3fe00000; + return argument.dbl; + } + -- cgit v1.2.3