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/* Copyright (C) 1988-1991 Apple Computer, Inc.
* All Rights Reserved.
*
* Warranty Information
* Even though Apple has reviewed this software, Apple makes no warranty
* or representation, either express or implied, with respect to this
* software, its quality, accuracy, merchantability, or fitness for a
* particular purpose. As a result, this software is provided "as is,"
* and you, its user, are assuming the entire risk as to its quality
* and accuracy.
*
* This code may be used and freely distributed as long as it includes
* this copyright notice and the warranty information.
*
* Machine-independent I/O routines for IEEE FLOATing-point numbers.
*
* NaN's and infinities are converted to HUGE_VAL or HUGE, which
* happens to be infinity on IEEE machines. Unfortunately, it is
* impossible to preserve NaN's in a machine-independent way.
* Infinities are, however, preserved on IEEE machines.
*
* These routines have been tested on the following machines:
* Apple Macintosh, MPW 3.1 C compiler
* Apple Macintosh, THINK C compiler
* Silicon Graphics IRIS, MIPS compiler
* Cray X/MP and Y/MP
* Digital Equipment VAX
* Sequent Balance (Multiprocesor 386)
* NeXT
*
*
* Implemented by Malcolm Slaney and Ken Turkowski.
*
* Malcolm Slaney contributions during 1988-1990 include big- and little-
* endian file I/O, conversion to and from Motorola's extended 80-bit
* FLOATing-point format, and conversions to and from IEEE single-
* precision FLOATing-point format.
*
* In 1991, Ken Turkowski implemented the conversions to and from
* IEEE double-precision format, added more precision to the extended
* conversions, and accommodated conversions involving +/- infinity,
* NaN's, and denormalized numbers.
*
* $Id: ieeeFLOAT.c,v 1.1 1993/06/11 17:45:46 malcolm Exp $
*
* $Log: ieeeFLOAT.c,v $
* Revision 1.1 1993/06/11 17:45:46 malcolm
* Initial revision
*
*/
#include <stdio.h>
#include <math.h>
#include "ieeefloat.h"
#include "common.h"
# define FloatToUnsigned(f) ((unsigned long)(((long)((f) - 2147483648.0)) + 2147483647L + 1))
# define UnsignedToFloat(u) (((double)((long)((u) - 2147483647L - 1))) + 2147483648.0)
double ConvertFromIeeeExtended (bytes)
char *bytes;
{
double f;
long expon;
unsigned long hiMant, loMant;
expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
hiMant = ((unsigned long) (bytes[2] & 0xFF) << 24)
| ((unsigned long) (bytes[3] & 0xFF) << 16) |
((unsigned long) (bytes[4] & 0xFF) << 8) |
((unsigned long) (bytes[5] & 0xFF));
loMant = ((unsigned long) (bytes[6] & 0xFF) << 24)
| ((unsigned long) (bytes[7] & 0xFF) << 16) |
((unsigned long) (bytes[8] & 0xFF) << 8) |
((unsigned long) (bytes[9] & 0xFF));
if (expon == 0 && hiMant == 0 && loMant == 0) {
f = 0;
} else {
if (expon == 0x7FFF) { /* Infinity or NaN */
f = HUGE_VAL;
} else {
expon -= 16383;
f = ldexp (UnsignedToFloat (hiMant), expon -= 31);
f += ldexp (UnsignedToFloat (loMant), expon -= 32);
}
}
if (bytes[0] & 0x80)
return -f;
else
return f;
}
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