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/* Copyright (C) 1989-1991 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 above 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.
*/
/****************************************************************
* Extended precision IEEE floating-point conversion routines.
* Extended is an 80-bit number as defined by Motorola,
* with a sign bit, 15 bits of exponent (offset 16383?),
* and a 64-bit mantissa, with no hidden bit.
****************************************************************/
#include "extended.h"
#include <math.h>
#ifndef HUGE_VAL
#define HUGE_VAL HUGE
#endif
#define FloatToUnsigned(f) ((unsigned long) (((long) (f - 2147483648.0)) + 2147483647L) + 1)
void _af_convert_to_ieee_extended (double num, unsigned char *bytes)
{
int sign;
int expon;
double fMant, fsMant;
unsigned long hiMant, loMant;
if (num < 0) {
sign = 0x8000;
num *= -1;
} else {
sign = 0;
}
if (num == 0) {
expon = 0; hiMant = 0; loMant = 0;
}
else {
fMant = frexp(num, &expon);
if ((expon > 16384) || !(fMant < 1)) { /* Infinity or NaN */
expon = sign|0x7FFF; hiMant = 0; loMant = 0; /* infinity */
}
else { /* Finite */
expon += 16382;
if (expon < 0) { /* denormalized */
fMant = ldexp(fMant, expon);
expon = 0;
}
expon |= sign;
fMant = ldexp(fMant, 32);
fsMant = floor(fMant);
hiMant = FloatToUnsigned(fsMant);
fMant = ldexp(fMant - fsMant, 32);
fsMant = floor(fMant);
loMant = FloatToUnsigned(fsMant);
}
}
bytes[0] = expon >> 8;
bytes[1] = expon;
bytes[2] = hiMant >> 24;
bytes[3] = hiMant >> 16;
bytes[4] = hiMant >> 8;
bytes[5] = hiMant;
bytes[6] = loMant >> 24;
bytes[7] = loMant >> 16;
bytes[8] = loMant >> 8;
bytes[9] = loMant;
}
#define UnsignedToFloat(u) (((double) ((long) (u - 2147483647L - 1))) + 2147483648.0)
double _af_convert_from_ieee_extended (const unsigned char *bytes)
{
double f;
int 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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