src/common/extended.c

   1 /*****************************************************************************
   2 ** Name:        src/common/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 *****************************************************************************/
   8
   9
  10 #if defined(_WIN32_WCE)
  11     /* eVC cause warnings in its own headers: stdlib.h and winnt.h */
  12     #pragma warning (disable:4115)
  13     #pragma warning (disable:4214)
  14 #endif
  15
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <ctype.h>
  19 #include <limits.h>
  20 #include <string.h>
  21 #include "wx/defs.h"
  22
  23 #if defined(_WIN32_WCE)
  24     #pragma warning (default:4115)
  25     #pragma warning (default:4214)
  26 #endif
  27
  28 #if wxUSE_APPLE_IEEE
  29
  30 #include "wx/math.h"
  31
  32 /* Copyright (C) 1989-1991 Ken Turkowski. <turk@computer.org>
  33  *
  34  * All rights reserved.
  35  *
  36  * Warranty Information
  37  *  Even though I have reviewed this software, I make no warranty
  38  *  or representation, either express or implied, with respect to this
  39  *  software, its quality, accuracy, merchantability, or fitness for a
  40  *  particular purpose.  As a result, this software is provided "as is,"
  41  *  and you, its user, are assuming the entire risk as to its quality
  42  *  and accuracy.
  43  *
  44  * This code may be used and freely distributed as long as it includes
  45  * this copyright notice and the above warranty information.
  46  *
  47  * Machine-independent I/O routines for IEEE floating-point numbers.
  48  *
  49  * NaN's and infinities are converted to HUGE_VAL or HUGE, which
  50  * happens to be infinity on IEEE machines.  Unfortunately, it is
  51  * impossible to preserve NaN's in a machine-independent way.
  52  * Infinities are, however, preserved on IEEE machines.
  53  *
  54  * These routines have been tested on the following machines:
  55  *    Apple Macintosh, MPW 3.1 C compiler
  56  *    Apple Macintosh, THINK C compiler
  57  *    Silicon Graphics IRIS, MIPS compiler
  58  *    Cray X/MP and Y/MP
  59  *    Digital Equipment VAX
  60  *    Sequent Balance (Multiprocesor 386)
  61  *    NeXT
  62  *
  63  *
  64  * Implemented by Malcolm Slaney and Ken Turkowski.
  65  *
  66  * Malcolm Slaney contributions during 1988-1990 include big- and little-
  67  * endian file I/O, conversion to and from Motorola's extended 80-bit
  68  * floating-point format, and conversions to and from IEEE single-
  69  * precision floating-point format.
  70  *
  71  * In 1991, Ken Turkowski implemented the conversions to and from
  72  * IEEE double-precision format, added more precision to the extended
  73  * conversions, and accommodated conversions involving +/- infinity,
  74  * NaN's, and denormalized numbers.
  75  */
  76
  77 #ifndef HUGE_VAL
  78 # define HUGE_VAL HUGE
  79 #endif /*HUGE_VAL*/
  80
  81
  82 /****************************************************************
  83  * The following two routines make up for deficiencies in many
  84  * compilers to convert properly between unsigned integers and
  85  * floating-point.  Some compilers which have this bug are the
  86  * THINK_C compiler for the Macintosh and the C compiler for the
  87  * Silicon Graphics MIPS-based Iris.
  88  ****************************************************************/
  89
  90 #ifdef applec    /* The Apple C compiler works */
  91 # define FloatToUnsigned(f)   ((wxUint32)(f))
  92 # define UnsignedToFloat(u)   ((wxFloat64)(u))
  93 #else /*applec*/
  94 # define FloatToUnsigned(f)   ((wxUint32)(((wxInt32)((f) - 2147483648.0)) + 2147483647L) + 1)
  95 # define UnsignedToFloat(u)   (((wxFloat64)((wxInt32)((u) - 2147483647L - 1))) + 2147483648.0)
  96 #endif /*applec*/
  97
  98
  99
 100 /****************************************************************
 101  * Extended precision IEEE floating-point conversion routines.
 102  * Extended is an 80-bit number as defined by Motorola,
 103  * with a sign bit, 15 bits of exponent (offset 16383?),
 104  * and a 64-bit mantissa, with no hidden bit.
 105  ****************************************************************/
 106
 107 WXDLLIMPEXP_BASE wxFloat64 wxConvertFromIeeeExtended(const wxInt8 *bytes)
 108 {
 109     wxFloat64 f;
 110     wxInt32 expon;
 111     wxUint32 hiMant, loMant;
 112
 113     expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
 114     hiMant = ((wxUint32)(bytes[2] & 0xFF) << 24)
 115             | ((wxUint32)(bytes[3] & 0xFF) << 16)
 116             | ((wxUint32)(bytes[4] & 0xFF) << 8)
 117             | ((wxUint32)(bytes[5] & 0xFF));
 118     loMant = ((wxUint32)(bytes[6] & 0xFF) << 24)
 119             | ((wxUint32)(bytes[7] & 0xFF) << 16)
 120             | ((wxUint32)(bytes[8] & 0xFF) << 8)
 121             | ((wxUint32)(bytes[9] & 0xFF));
 122
 123     if (expon == 0 && hiMant == 0 && loMant == 0) {
 124         f = 0;
 125     }
 126     else {
 127         if (expon == 0x7FFF) { /* Infinity or NaN */
 128             f = HUGE_VAL;
 129         }
 130         else {
 131             expon -= 16383;
 132             f  = ldexp(UnsignedToFloat(hiMant), expon-=31);
 133             f += ldexp(UnsignedToFloat(loMant), expon-=32);
 134         }
 135     }
 136
 137     if (bytes[0] & 0x80)
 138         return -f;
 139     else
 140         return f;
 141 }
 142
 143
 144 /****************************************************************/
 145
 146
 147 WXDLLIMPEXP_BASE void wxConvertToIeeeExtended(wxFloat64 num, wxInt8 *bytes)
 148 {
 149     wxInt32 sign;
 150     wxInt32 expon;
 151     wxFloat64 fMant, fsMant;
 152     wxUint32 hiMant, loMant;
 153
 154     if (num < 0) {
 155         sign = 0x8000;
 156         num *= -1;
 157     } else {
 158         sign = 0;
 159     }
 160
 161     if (num == 0) {
 162         expon = 0; hiMant = 0; loMant = 0;
 163     }
 164     else {
 165         fMant = frexp(num, &expon);
 166         if ((expon > 16384) || !(fMant < 1)) { /* Infinity or NaN */
 167             expon = sign|0x7FFF; hiMant = 0; loMant = 0; /* infinity */
 168         }
 169         else { /* Finite */
 170             expon += 16382;
 171             if (expon < 0) { /* denormalized */
 172                 fMant = ldexp(fMant, expon);
 173                 expon = 0;
 174             }
 175             expon |= sign;
 176             fMant = ldexp(fMant, 32);          fsMant = floor(fMant); hiMant = FloatToUnsigned(fsMant);
 177             fMant = ldexp(fMant - fsMant, 32); fsMant = floor(fMant); loMant = FloatToUnsigned(fsMant);
 178         }
 179     }
 180
 181     bytes[0] = expon >> 8;
 182     bytes[1] = expon;
 183     bytes[2] = hiMant >> 24;
 184     bytes[3] = hiMant >> 16;
 185     bytes[4] = hiMant >> 8;
 186     bytes[5] = hiMant;
 187     bytes[6] = loMant >> 24;
 188     bytes[7] = loMant >> 16;
 189     bytes[8] = loMant >> 8;
 190     bytes[9] = loMant;
 191 }
 192
 193 #if WXWIN_COMPATIBILITY_2_8
 194 WXDLLIMPEXP_BASE wxFloat64 ConvertFromIeeeExtended(const wxInt8 *bytes)
 195 {
 196     return wxConvertFromIeeeExtended(bytes);
 197 }
 198
 199 WXDLLIMPEXP_BASE void ConvertToIeeeExtended(wxFloat64 num, wxInt8 *bytes)
 200 {
 201     wxConvertToIeeeExtended(num, bytes);
 202 }
 203 #endif // WXWIN_COMPATIBILITY_2_8
 204
 205 #endif /* wxUSE_APPLE_IEEE */