/* * Copyright (c) 2002 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * The contents of this file constitute Original Code as defined in and * are subject to the Apple Public Source License Version 1.1 (the * "License"). You may not use this file except in compliance with the * License. Please obtain a copy of the License at * http://www.apple.com/publicsource and read it before using this file. * * This Original Code and all software distributed under the License are * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the * License for the specific language governing rights and limitations * under the License. * * @APPLE_LICENSE_HEADER_END@ */ /******************************************************************************* * * * File hypot.c, * * Function hypot(x,y), * * Implementation of sqrt(x^2+y^2) for the PowerPC. * * * * Copyright © 1991 Apple Computer, Inc. All rights reserved. * * * * Written by Ali Sazegari, started on November 1991, * * * * based on math.h, library code for Macintoshes with a 68881/68882 * * by Jim Thomas. * * * * W A R N I N G: This routine expects a 64 bit double model. * * * * December 03 1992: first rs6000 port. * * January 05 1993: added the environmental controls. * * July 14 1993: added #pragma fenv_access. changed feholdexcept * * to the internal routine _feprocentry. * * September22 1993: conforming to nceg-fpce specification for ±° values. * * September19 1994: revamp of the algorithm for performance. * * * *******************************************************************************/ #include "math.h" #include "fenv.h" #include "fp_private.h" #include "fenv_private.h" #include <System/ppc/cpu_capabilities.h> inline static uint32_t __attribute__((always_inline)) _get_cpu_capabilities(void) { uint32_t caps; asm("lwz %0, %1(0)" : "=r" (caps) : "I" (_COMM_PAGE_CPU_CAPABILITIES)); return caps; } /******************************************************************************* * Functions needed for the computation. * *******************************************************************************/ /* the following fp.h functions are used: */ /* fabs and sqrt; */ /* the following environmental functions are used: */ /* feclearexcept, _feprocentry and feupdateenv. */ #pragma STDC FENV_ACCESS ON static const hexdouble Huge = HEXDOUBLE(0x7FF00000, 0x00000000); static const hexdouble NegHuge = HEXDOUBLE(0xFFF00000, 0x00000000); double hypot ( double x, double y ) { register double temp; hexdouble OldEnvironment, CurrentEnvironment; register double FPR_env, FPR_z, FPR_one, FPR_inf, FPR_Minf, FPR_absx, FPR_absy, FPR_big, FPR_small; FPR_z = 0.0; FPR_one = 1.0; FPR_inf = Huge.d; FPR_Minf = NegHuge.d; FPR_absx = __FABS( x ); FPR_absy = __FABS( y ); /******************************************************************************* * If argument is SNaN then a QNaN has to be returned and the invalid * * flag signaled. * *******************************************************************************/ if (unlikely( ( x == FPR_inf ) || ( y == FPR_inf ) || ( x == FPR_Minf ) || ( y == FPR_Minf ) )) return FPR_inf; if (unlikely( ( x != x ) || ( y != y ) )) { x = __FABS ( x + y ); return x; } if ( FPR_absx > FPR_absy ) { FPR_big = FPR_absx; FPR_small = FPR_absy; } else { FPR_big = FPR_absy; FPR_small = FPR_absx; } // Now +0.0 <= FPR_small <= FPR_big < INFINITY if (unlikely( FPR_small == FPR_z )) return FPR_big; FEGETENVD( FPR_env ); // save environment, set default FESETENVD( FPR_z ); temp = FPR_small / FPR_big; OldEnvironment.d = FPR_env; temp = FPR_one + temp * temp; if (likely((_get_cpu_capabilities() & kHasFsqrt))) temp = __fsqrt ( temp ); else temp = sqrt ( temp ); FEGETENVD_GRP( CurrentEnvironment.d ); CurrentEnvironment.i.lo &= ~FE_UNDERFLOW; // Clear any inconsequential underflow FESETENVD_GRP( CurrentEnvironment.d ); temp = FPR_big * temp; // Might raise UNDERFLOW or OVERFLOW FEGETENVD_GRP( CurrentEnvironment.d ); OldEnvironment.i.lo |= CurrentEnvironment.i.lo; // Pick up any UF or OF FESETENVD_GRP( OldEnvironment.d ); // restore caller's environment return temp; }