src/common/extended.c

   1 /*****************************************************************************
   2 ** Name:        extended.c
   3 ** Purpose:     IEEE Extended<->Double routines to save floats to file
   4 ** Maintainer:  Ryan Norton
   5 ** Modified by:
   6 ** Created:     11/24/04
   7 ** RCS-ID:      $Id$
   8 *****************************************************************************/
   9
  10
  11 #if defined(_WIN32_WCE)
  12     /* eVC cause warnings in its own headers: stdlib.h and winnt.h */
  13     #pragma warning (disable:4115)
  14     #pragma warning (disable:4214)
  15 #endif
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <ctype.h>
  20 #include <limits.h>
  21 #include <string.h>
  22 #include "wx/defs.h"
  23
  24 #if defined(_WIN32_WCE)
  25     #pragma warning (default:4115)
  26     #pragma warning (default:4214)
  27 #endif
  28
  29 #if wxUSE_APPLE_IEEE
  30
  31 #include "wx/math.h"
  32
  33 /* Copyright (C) 1989-1991 Ken Turkowski. <turk@computer.org>
  34  *
  35  * All rights reserved.
  36  *
  37  * Warranty Information
  38  *  Even though I have reviewed this software, I make no warranty
  39  *  or representation, either express or implied, with respect to this
  40  *  software, its quality, accuracy, merchantability, or fitness for a
  41  *  particular purpose.  As a result, this software is provided "as is,"
  42  *  and you, its user, are assuming the entire risk as to its quality
  43  *  and accuracy.
  44  *
  45  * This code may be used and freely distributed as long as it includes
  46  * this copyright notice and the above warranty information.
  47  *
  48  * Machine-independent I/O routines for IEEE floating-point numbers.
  49  *
  50  * NaN's and infinities are converted to HUGE_VAL or HUGE, which
  51  * happens to be infinity on IEEE machines.  Unfortunately, it is
  52  * impossible to preserve NaN's in a machine-independent way.
  53  * Infinities are, however, preserved on IEEE machines.
  54  *
  55  * These routines have been tested on the following machines:
  56  *    Apple Macintosh, MPW 3.1 C compiler
  57  *    Apple Macintosh, THINK C compiler
  58  *    Silicon Graphics IRIS, MIPS compiler
  59  *    Cray X/MP and Y/MP
  60  *    Digital Equipment VAX
  61  *    Sequent Balance (Multiprocesor 386)
  62  *    NeXT
  63  *
  64  *
  65  * Implemented by Malcolm Slaney and Ken Turkowski.
  66  *
  67  * Malcolm Slaney contributions during 1988-1990 include big- and little-
  68  * endian file I/O, conversion to and from Motorola's extended 80-bit
  69  * floating-point format, and conversions to and from IEEE single-
  70  * precision floating-point format.
  71  *
  72  * In 1991, Ken Turkowski implemented the conversions to and from
  73  * IEEE double-precision format, added more precision to the extended
  74  * conversions, and accommodated conversions involving +/- infinity,
  75  * NaN's, and denormalized numbers.
  76  */
  77
  78 #ifndef HUGE_VAL
  79 # define HUGE_VAL HUGE
  80 #endif /*HUGE_VAL*/
  81
  82
  83 /****************************************************************
  84  * The following two routines make up for deficiencies in many
  85  * compilers to convert properly between unsigned integers and
  86  * floating-point.  Some compilers which have this bug are the
  87  * THINK_C compiler for the Macintosh and the C compiler for the
  88  * Silicon Graphics MIPS-based Iris.
  89  ****************************************************************/
  90
  91 #ifdef applec    /* The Apple C compiler works */
  92 # define FloatToUnsigned(f)   ((wxUint32)(f))
  93 # define UnsignedToFloat(u)   ((wxFloat64)(u))
  94 #else /*applec*/
  95 # define FloatToUnsigned(f)   ((wxUint32)(((wxInt32)((f) - 2147483648.0)) + 2147483647L) + 1)
  96 # define UnsignedToFloat(u)   (((wxFloat64)((wxInt32)((u) - 2147483647L - 1))) + 2147483648.0)
  97 #endif /*applec*/
  98
  99
 100
 101 /****************************************************************
 102  * Extended precision IEEE floating-point conversion routines.
 103  * Extended is an 80-bit number as defined by Motorola,
 104  * with a sign bit, 15 bits of exponent (offset 16383?),
 105  * and a 64-bit mantissa, with no hidden bit.
 106  ****************************************************************/
 107
 108 wxFloat64 ConvertFromIeeeExtended(const wxInt8 *bytes)
 109 {
 110     wxFloat64 f;
 111     wxInt32 expon;
 112     wxUint32 hiMant, loMant;
 113
 114     expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
 115     hiMant = ((wxUint32)(bytes[2] & 0xFF) << 24)
 116             | ((wxUint32)(bytes[3] & 0xFF) << 16)
 117             | ((wxUint32)(bytes[4] & 0xFF) << 8)
 118             | ((wxUint32)(bytes[5] & 0xFF));
 119     loMant = ((wxUint32)(bytes[6] & 0xFF) << 24)
 120             | ((wxUint32)(bytes[7] & 0xFF) << 16)
 121             | ((wxUint32)(bytes[8] & 0xFF) << 8)
 122             | ((wxUint32)(bytes[9] & 0xFF));
 123
 124     if (expon == 0 && hiMant == 0 && loMant == 0) {
 125         f = 0;
 126     }
 127     else {
 128         if (expon == 0x7FFF) { /* Infinity or NaN */
 129             f = HUGE_VAL;
 130         }
 131         else {
 132             expon -= 16383;
 133             f  = ldexp(UnsignedToFloat(hiMant), expon-=31);
 134             f += ldexp(UnsignedToFloat(loMant), expon-=32);
 135         }
 136     }
 137
 138     if (bytes[0] & 0x80)
 139         return -f;
 140     else
 141         return f;
 142 }
 143
 144
 145 /****************************************************************/
 146
 147
 148 void ConvertToIeeeExtended(wxFloat64 num, wxInt8 *bytes)
 149 {
 150     wxInt32 sign;
 151     wxInt32 expon;
 152     wxFloat64 fMant, fsMant;
 153     wxUint32 hiMant, loMant;
 154
 155     if (num < 0) {
 156         sign = 0x8000;
 157         num *= -1;
 158     } else {
 159         sign = 0;
 160     }
 161
 162     if (num == 0) {
 163         expon = 0; hiMant = 0; loMant = 0;
 164     }
 165     else {
 166         fMant = frexp(num, &expon);
 167         if ((expon > 16384) || !(fMant < 1)) { /* Infinity or NaN */
 168             expon = sign|0x7FFF; hiMant = 0; loMant = 0; /* infinity */
 169         }
 170         else { /* Finite */
 171             expon += 16382;
 172             if (expon < 0) { /* denormalized */
 173                 fMant = ldexp(fMant, expon);
 174                 expon = 0;
 175             }
 176             expon |= sign;
 177             fMant = ldexp(fMant, 32);          fsMant = floor(fMant); hiMant = FloatToUnsigned(fsMant);
 178             fMant = ldexp(fMant - fsMant, 32); fsMant = floor(fMant); loMant = FloatToUnsigned(fsMant);
 179         }
 180     }
 181
 182     bytes[0] = expon >> 8;
 183     bytes[1] = expon;
 184     bytes[2] = hiMant >> 24;
 185     bytes[3] = hiMant >> 16;
 186     bytes[4] = hiMant >> 8;
 187     bytes[5] = hiMant;
 188     bytes[6] = loMant >> 24;
 189     bytes[7] = loMant >> 16;
 190     bytes[8] = loMant >> 8;
 191     bytes[9] = loMant;
 192 }
 193
 194
 195
 196 #endif /* wxUSE_APPLE_IEEE */