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/*
* C O N V E R T T O I E E E E X T E N D E D
*/
/* Copyright (C) 1988-1991 Apple Computer, Inc.
* All rights reserved.
*
* 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
*
*
* 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.
*/
#include "math.h"
#ifndef HUGE_VAL
#ifdef HUGE
#define HUGE_VAL HUGE
#else
/* WARNING: this is machine-dependent and should come from math.h */
#define HUGE_VAL 1.797693134862315e308
#endif /* HUGE */
#endif /*HUGE_VAL*/
# define FloatToUnsigned(f) ((unsigned long)(((long)(f - 2147483648.0)) + 2147483647L) + 1)
void ConvertToIeeeExtended(double num, 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] = (char) (expon >> 8);
bytes[1] = (char) expon;
bytes[2] = (char) (hiMant >> 24);
bytes[3] = (char) (hiMant >> 16);
bytes[4] = (char) (hiMant >> 8);
bytes[5] = (char) hiMant;
bytes[6] = (char) (loMant >> 24);
bytes[7] = (char) (loMant >> 16);
bytes[8] = (char) (loMant >> 8);
bytes[9] = (char) loMant;
}
/*
* C O N V E R T F R O M I E E E E X T E N D E D
*/
/*
* Copyright (C) 1988-1991 Apple Computer, Inc.
* All rights reserved.
*
* 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
*
*
* 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.
*/
#ifndef HUGE_VAL
# define HUGE_VAL HUGE
#endif /*HUGE_VAL*/
# define UnsignedToFloat(u) (((double)((long)(u - 2147483647L - 1))) + 2147483648.0)
/****************************************************************
* Extended precision IEEE floating-point conversion routine.
****************************************************************/
double ConvertFromIeeeExtended(unsigned char *bytes /* LCN */)
{
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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