chiark - git - mdw - mLib/blob - utils/fltfmt-convert.c

   1 /* -*-c-*-
   2  *
   3  * Direct floating-point format conversions
   4  *
   5  * (c) 2024 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the mLib utilities library.
  11  *
  12  * mLib is free software: you can redistribute it and/or modify it under
  13  * the terms of the GNU Library General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or (at
  15  * your option) any later version.
  16  *
  17  * mLib is distributed in the hope that it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
  20  * License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with mLib.  If not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  25  * USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include "config.h"
  31
  32 #include "bits.h"
  33 #include "fltfmt.h"
  34
  35 /*----- Main code ---------------------------------------------------------*/
  36
  37 /* Macro machinery. */
  38
  39 #define CONVERSIONS(_)                                                  \
  40   _(float, flt, f32)                                                    \
  41   _(double, dbl, f64)
  42
  43 #if defined(__hppa__) || (defined(__mips__) && !defined(__mips_nan2008))
  44 #  define FROB_NANS
  45 #endif
  46
  47 #define CONV_DECLS_flt_f32 uint32 t
  48 #if (FLT_FORMAT&(FLTFMT_ORGMASK | FLTFMT_TYPEMASK)) == FLTFMT_IEEE_F32
  49 #  if (FLT_FORMAT&FLTFMT_ENDMASK) == FLTFMT_BE
  50 #    define CONV_LOAD_flt_f32 do { t = LOAD32_B(&x); } while (0)
  51 #    define CONV_STORE_flt_f32 do { STORE32_B(z_out, t); } while (0)
  52 #  elif (FLT_FORMAT&FLTFMT_ENDMASK) == FLTFMT_LE
  53 #    define CONV_LOAD_flt_f32 do { t = LOAD32_L(&x); } while (0)
  54 #    define CONV_STORE_flt_f32 do { STORE32_L(z_out, t); } while (0)
  55 #  else
  56 #    error "unimplemented byte order"
  57 #  endif
  58 #  ifdef FROB_NANS
  59 #    define CONV_FROBNANflt_f32 do {                                    \
  60        if ((t&0x7f800000) != 0x7f800000 || !(t&0x007fffff))             \
  61          ;                                                              \
  62        else if (t&0x003fffff)                                           \
  63          t ^= 0x00400000;                                               \
  64        else {                                                           \
  65          t = (t&0x80000000) | 0x00000001;                               \
  66          rc |= FLTERR_INEXACT;                                          \
  67        }                                                                \
  68      } while (0)
  69 #  else
  70 #    define CONV_FROBNANflt_f32 do ; while (0)
  71 #  endif
  72 #else
  73 #  define CONV_LOAD_flt_f32 do {                                        \
  74      struct floatbits u = FLOATBITS_INIT;                               \
  75      rc |= fltfmt_decflt(&u, x, r);                                     \
  76      rc |= fltfmt_encieee(&fltfmt_f32, &t, &u, r, FLTERR_ALLERRS);      \
  77      fltfmt_freebits(&u);                                               \
  78    } while (0)
  79 #  define CONV_STORE_flt_f32 do {                                       \
  80      struct floatbits u = FLOATBITS_INIT;                               \
  81      rc |= fltfmt_decieee(&fltfmt_f32, &u, &t);                         \
  82      rc |= fltfmt_encflt(z_out, &u, r);                                 \
  83      fltfmt_freebits(&u);                                               \
  84    } while (0)
  85 #  define CONV_FROBNANflt_f32 do ; while (0)
  86 #endif
  87 #define CONV_LOADB_flt_f32 do { t = LOAD32_B(p); } while (0)
  88 #define CONV_LOADL_flt_f32 do { t = LOAD32_L(p); } while (0)
  89 #define CONV_STOREB_flt_f32 do { STORE32_B(p, t); } while (0)
  90 #define CONV_STOREL_flt_f32 do { STORE32_L(p, t); } while (0)
  91
  92 #define CONV_DECLS_dbl_f64 kludge64 t
  93 #if (DBL_FORMAT&(FLTFMT_ORGMASK | FLTFMT_TYPEMASK)) == FLTFMT_IEEE_F64
  94 #  if (DBL_FORMAT&FLTFMT_ENDMASK) == FLTFMT_BE
  95 #    define CONV_LOAD_dbl_f64 do { LOAD64_B_(t, &x); } while (0)
  96 #    define CONV_STORE_dbl_f64 do { STORE64_B_(z_out, t); } while (0)
  97 #  elif (DBL_FORMAT&FLTFMT_ENDMASK) == FLTFMT_LE
  98 #    define CONV_LOAD_dbl_f64 do { LOAD64_L_(t, &x); } while (0)
  99 #    define CONV_STORE_dbl_f64 do { STORE64_L_(z_out, t); } while (0)
 100 #  else
 101 #    error "unimplemented byte order"
 102 #  endif
 103 #  ifdef FROB_NANS
 104 #    define CONV_FROBNANdbl_f64 do {                                    \
 105        kludge64 u, v;                                                   \
 106        SET64(u, 0x7ff00000, 0x00000000); AND64(v, t, u);                \
 107        if (CMP64(v, ==, u)) {                                           \
 108          SET64(u, 0x000fffff, 0xffffffff); AND64(v, t, u);              \
 109          if (!ZERO64(v)) {                                              \
 110            SET64(u, 0x0007ffff, 0xffffffff); AND64(v, t, u);            \
 111            if (!ZERO64(v))                                              \
 112              { SET64(u, 0x00080000, 0x00000000); XOR64(t, t, u); }      \
 113            else {                                                       \
 114              SET64(u, 0x80000000, 0x00000000); AND64(t, t, u);          \
 115              SET64(u, 0x00000000, 0x00000001); OR64(t, t, u);           \
 116              rc |= FLTERR_INEXACT;                                      \
 117            }                                                            \
 118          }                                                              \
 119        }                                                                \
 120      } while (0)
 121 #  else
 122 #    define CONV_FROBNANdbl_f64 do ; while (0)
 123 #  endif
 124 #else
 125 #  define CONV_LOAD_dbl_f64 do {                                        \
 126      struct floatbits u = FLOATBITS_INIT; uint32 v[2];                  \
 127      rc |= fltfmt_decdbl(&u, x, r);                                     \
 128      rc |= fltfmt_encieee(&fltfmt_f64, v, &u, r, FLTERR_ALLERRS);       \
 129      SET64(t, v[0], v[1]); fltfmt_freebits(&u);                         \
 130    } while (0)
 131 #  define CONV_STORE_dbl_f64 do {                                       \
 132      struct floatbits u = FLOATBITS_INIT; uint32 v[2];                  \
 133      v[0] = HI64(t); v[1] = LO64(t);                                    \
 134      rc |= fltfmt_decieee(&fltfmt_f64, &u, v);                          \
 135      rc |= fltfmt_encdbl(z_out, &u, r);                                 \
 136      fltfmt_freebits(&u);                                               \
 137    } while (0)
 138 #  define CONV_FROBNANdbl_f64 do ; while (0)
 139 #endif
 140 #define CONV_LOADB_dbl_f64 do { LOAD64_B_(t, p); } while (0)
 141 #define CONV_LOADL_dbl_f64 do { LOAD64_L_(t, p); } while (0)
 142 #define CONV_STOREB_dbl_f64 do { STORE64_B_(p, t); } while (0)
 143 #define CONV_STOREL_dbl_f64 do { STORE64_L_(p, t); } while (0)
 144
 145 /* --- @fltfmt_CTYtoFTYE@ --- *
 146  *
 147  * Arguments:   @octet *p@ = output pointer
 148  *              @float x@, @double x@ = value to convert
 149  *              @unsigned r@ = rounding mode
 150  *
 151  * Returns:     Error flags (@FLTERR_...@).
 152  *
 153  * Use:         Encode a native C floating-point value in an external format.
 154  *
 155  *              The @CTY@ is an abbreviation for a C type: @flt@ for @float@,
 156  *              or @dbl@ for @double@; @fty@ is an abbreviation for the
 157  *              external format, @f32@ for IEEE Binary32, or @f64@ for IEEE
 158  *              Binary64; and @E@ is @l@ for little-endian or @b@ for
 159  *              big-endian byte order.  Not all combinations are currently
 160  *              supported.
 161  *
 162  *              On platforms where the external format is used natively,
 163  *              these functions are simple data copies.
 164  */
 165
 166 #define DEF_CONV(ctype, cty, fty)                                       \
 167   unsigned fltfmt_##cty##to##fty##l(octet *p, ctype x, unsigned r)      \
 168   {                                                                     \
 169     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 170                                                                         \
 171     CONV_LOAD_##cty##_##fty;                                            \
 172     CONV_FROBNAN##cty##_##fty;                                          \
 173     CONV_STOREL_##cty##_##fty;                                          \
 174     return (rc);                                                        \
 175   }                                                                     \
 176                                                                         \
 177   unsigned fltfmt_##cty##to##fty##b(octet *p, ctype x, unsigned r)      \
 178   {                                                                     \
 179     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 180                                                                         \
 181     CONV_LOAD_##cty##_##fty;                                            \
 182     CONV_FROBNAN##cty##_##fty;                                          \
 183     CONV_STOREB_##cty##_##fty;                                          \
 184     return (rc);                                                        \
 185   }
 186
 187 CONVERSIONS(DEF_CONV)
 188
 189 #undef DEF_CONV
 190
 191 /* --- @fltfmt_FTYEtoCTY@ --- *
 192  *
 193  * Arguments:   @float *z_out@, @double *z_out@ = storage for output
 194  *              @const octet *p@ = input pointer
 195  *              @unsigned r@ = rounding mode
 196  *
 197  * Returns:     Error flags (@FLTERR_...@).
 198  *
 199  * Use:         Decodes a floating point value in an external format into a
 200  *              native value.
 201  *
 202  *              The naming conventions are the same as for @fltfmt_dbltof64b@
 203  *              above.
 204  *
 205  *              On platforms where the external format is used natively,
 206  *              these functions are simple data copies.
 207  */
 208
 209 #define DEF_CONV(ctype, cty, fty)                                       \
 210   unsigned fltfmt_##fty##lto##cty(ctype *z_out, const octet *p, unsigned r) \
 211   {                                                                     \
 212     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 213                                                                         \
 214     CONV_LOADL_##cty##_##fty;                                           \
 215     CONV_FROBNAN##cty##_##fty;                                          \
 216     CONV_STORE_##cty##_##fty;                                           \
 217     return (rc);                                                        \
 218   }                                                                     \
 219                                                                         \
 220   unsigned fltfmt_##fty##bto##cty(ctype *z_out, const octet *p, unsigned r) \
 221   {                                                                     \
 222     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 223                                                                         \
 224     CONV_LOADB_##cty##_##fty;                                           \
 225     CONV_FROBNAN##cty##_##fty;                                          \
 226     CONV_STORE_##cty##_##fty;                                           \
 227     return (rc);                                                        \
 228   }
 229
 230 CONVERSIONS(DEF_CONV)
 231
 232 #undef DEF_CONV
 233
 234 /*----- That's all, folks -------------------------------------------------*/