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+/*******************************************************************************
+* *
+* File ceilfloor.c, *
+* Function ceil(x) and floor(x), *
+* Implementation of ceil and floor 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. *
+* July 14 1993: comment changes and addition of #pragma fenv_access. *
+* May 06 1997: port of the ibm/taligent ceil and floor routines. *
+* April 11 2001: first port to os x using gcc. *
+* June 13 2001: replaced __setflm with in-line assembly *
+* *
+*******************************************************************************/
+
+static const double twoTo52 = 4503599627370496.0;
+static const unsigned long signMask = 0x80000000ul;
+
+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;
+
+/*******************************************************************************
+* Functions needed for the computation. *
+*******************************************************************************/
+
+/*******************************************************************************
+* Floor(x) returns the largest integer not greater than x. *
+*******************************************************************************/
+
+double floor ( double x )
+ {
+ DblInHex xInHex,OldEnvironment;
+ register double y;
+ register unsigned long int xhi;
+ register long int target;
+
+ xInHex.dbl = x;
+ xhi = xInHex.words.hi & 0x7fffffffUL; // xhi is the high half of |x|
+ target = ( xInHex.words.hi < signMask );
+
+ if ( xhi < 0x43300000ul )
+/*******************************************************************************
+* Is |x| < 2.0^52? *
+*******************************************************************************/
+ {
+ if ( xhi < 0x3ff00000ul )
+/*******************************************************************************
+* Is |x| < 1.0? *
+*******************************************************************************/
+ {
+ if ( ( xhi | xInHex.words.lo ) == 0ul ) // zero x is exact case
+ return ( x );
+ else
+ { // inexact case
+ asm ("mffs %0" : "=f" (OldEnvironment.dbl));
+ OldEnvironment.words.lo |= 0x02000000ul;
+ asm ("mtfsf 255,%0" : /*NULLOUT*/ : /*IN*/ "f" ( OldEnvironment.dbl ));
+ if ( target )
+ return ( 0.0 );
+ else
+ return ( -1.0 );
+ }
+ }
+/*******************************************************************************
+* Is 1.0 < |x| < 2.0^52? *
+*******************************************************************************/
+ if ( target )
+ {
+ y = ( x + twoTo52 ) - twoTo52; // round at binary pt.
+ if ( y > x )
+ return ( y - 1.0 );
+ else
+ return ( y );
+ }
+
+ else
+ {
+ y = ( x - twoTo52 ) + twoTo52; // round at binary pt.
+ if ( y > x )
+ return ( y - 1.0 );
+ else
+ return ( y );
+ }
+ }
+/*******************************************************************************
+* |x| >= 2.0^52 or x is a NaN. *
+*******************************************************************************/
+ return ( x );
+ }
+