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

   1 /* -*-c-*-
   2  *
   3  * 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 #define CONV_DECLS_flt_f32 uint32 t
  44 #if (FLT_FORMAT&(FLTFMT_ORGMASK | FLTFMT_TYPEMASK)) == FLTFMT_IEEE_F32
  45 #  if (FLT_FORMAT&FLTFMT_ENDMASK) == FLTFMT_BE
  46 #    define CONV_LOAD_flt_f32 do { t = LOAD32_B(&x); } while (0)
  47 #    define CONV_STORE_flt_f32 do { STORE32_B(z_out, t); } while (0)
  48 #  elif (FLT_FORMAT&FLTFMT_ENDMASK) == FLTFMT_LE
  49 #    define CONV_LOAD_flt_f32 do { t = LOAD32_L(&x); } while (0)
  50 #    define CONV_STORE_flt_f32 do { STORE32_L(z_out, t); } while (0)
  51 #  else
  52 #    error "unimplemented byte order"
  53 #  endif
  54 #  ifdef FLTFMT__MUST_FROB_NANS
  55 #    define CONV_FROB_flt_f32 do { FLTFMT__FROB_NAN_F32(&t, rc); } while (0)
  56 #  else
  57 #    define CONV_FROB_flt_f32 do ; while (0)
  58 #  endif
  59 #else
  60 #  define CONV_LOAD_flt_f32 do {                                        \
  61      struct floatbits u = FLOATBITS_INIT;                               \
  62      rc |= fltfmt_decflt(&u, x, r);                                     \
  63      rc |= fltfmt_encieee(&fltfmt_f32, &t, &u, r, FLTERR_ALLERRS);      \
  64      fltfmt_freebits(&u);                                               \
  65    } while (0)
  66 #  define CONV_STORE_flt_f32 do {                                       \
  67      struct floatbits u = FLOATBITS_INIT;                               \
  68      rc |= fltfmt_decieee(&fltfmt_f32, &u, &t);                         \
  69      rc |= fltfmt_encflt(z_out, &u, r);                                 \
  70      fltfmt_freebits(&u);                                               \
  71    } while (0)
  72 #  define CONV_FROB_flt_f32 do ; while (0)
  73 #endif
  74 #define CONV_LOADB_flt_f32 do { t = LOAD32_B(p); } while (0)
  75 #define CONV_LOADL_flt_f32 do { t = LOAD32_L(p); } while (0)
  76 #define CONV_STOREB_flt_f32 do { STORE32_B(p, t); } while (0)
  77 #define CONV_STOREL_flt_f32 do { STORE32_L(p, t); } while (0)
  78
  79 #define CONV_DECLS_dbl_f64 kludge64 t
  80 #if (DBL_FORMAT&(FLTFMT_ORGMASK | FLTFMT_TYPEMASK)) == FLTFMT_IEEE_F64
  81 #  if (DBL_FORMAT&FLTFMT_ENDMASK) == FLTFMT_BE
  82 #    define CONV_LOAD_dbl_f64 do { LOAD64_B_(t, &x); } while (0)
  83 #    define CONV_STORE_dbl_f64 do { STORE64_B_(z_out, t); } while (0)
  84 #  elif (DBL_FORMAT&FLTFMT_ENDMASK) == FLTFMT_LE
  85 #    define CONV_LOAD_dbl_f64 do { LOAD64_L_(t, &x); } while (0)
  86 #    define CONV_STORE_dbl_f64 do { STORE64_L_(z_out, t); } while (0)
  87 #  else
  88 #    error "unimplemented byte order"
  89 #  endif
  90 #  ifdef FLTFMT__MUST_FROB_NANS
  91 #    define CONV_FROB_dbl_f64 do {                                      \
  92        uint32 u[2];                                                     \
  93        u[0] = HI64(t); u[1] = LO64(t);                                  \
  94        FLTFMT__FROB_NAN_F64(&u, rc);                                    \
  95        SET64(t, u[0], u[1]);                                            \
  96      } while (0)
  97 #  else
  98 #    define CONV_FROB_dbl_f64 do ; while (0)
  99 #  endif
 100 #else
 101 #  define CONV_LOAD_dbl_f64 do {                                        \
 102      struct floatbits u = FLOATBITS_INIT; uint32 v[2];                  \
 103      rc |= fltfmt_decdbl(&u, x, r);                                     \
 104      rc |= fltfmt_encieee(&fltfmt_f64, v, &u, r, FLTERR_ALLERRS);       \
 105      SET64(t, v[0], v[1]); fltfmt_freebits(&u);                         \
 106    } while (0)
 107 #  define CONV_STORE_dbl_f64 do {                                       \
 108      struct floatbits u = FLOATBITS_INIT; uint32 v[2];                  \
 109      v[0] = HI64(t); v[1] = LO64(t);                                    \
 110      rc |= fltfmt_decieee(&fltfmt_f64, &u, v);                          \
 111      rc |= fltfmt_encdbl(z_out, &u, r);                                 \
 112      fltfmt_freebits(&u);                                               \
 113    } while (0)
 114 #  define CONV_FROB_dbl_f64 do ; while (0)
 115 #endif
 116 #define CONV_LOADB_dbl_f64 do { LOAD64_B_(t, p); } while (0)
 117 #define CONV_LOADL_dbl_f64 do { LOAD64_L_(t, p); } while (0)
 118 #define CONV_STOREB_dbl_f64 do { STORE64_B_(p, t); } while (0)
 119 #define CONV_STOREL_dbl_f64 do { STORE64_L_(p, t); } while (0)
 120
 121 /* --- @fltfmt_CTYtoFTYE@ --- *
 122  *
 123  * Arguments:   @octet *p@ = output pointer
 124  *              @float x@, @double x@ = value to convert
 125  *              @unsigned r@ = rounding mode
 126  *
 127  * Returns:     Error flags (@FLTERR_...@).
 128  *
 129  * Use:         Encode a native C floating-point value in an external format.
 130  *
 131  *              The @CTY@ is an abbreviation for a C type: @flt@ for @float@,
 132  *              or @dbl@ for @double@; @fty@ is an abbreviation for the
 133  *              external format, @f32@ for IEEE Binary32, or @f64@ for IEEE
 134  *              Binary64; and @E@ is @l@ for little-endian or @b@ for
 135  *              big-endian byte order.  Not all combinations are currently
 136  *              supported.
 137  *
 138  *              On platforms where the external format is used natively,
 139  *              these functions are simple data copies.
 140  */
 141
 142 #define DEF_CONV(ctype, cty, fty)                                       \
 143   unsigned fltfmt_##cty##to##fty##l(octet *p, ctype x, unsigned r)      \
 144   {                                                                     \
 145     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 146                                                                         \
 147     CONV_LOAD_##cty##_##fty;                                            \
 148     CONV_FROB_##cty##_##fty;                                            \
 149     CONV_STOREL_##cty##_##fty;                                          \
 150     return (rc);                                                        \
 151   }                                                                     \
 152                                                                         \
 153   unsigned fltfmt_##cty##to##fty##b(octet *p, ctype x, unsigned r)      \
 154   {                                                                     \
 155     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 156                                                                         \
 157     CONV_LOAD_##cty##_##fty;                                            \
 158     CONV_FROB_##cty##_##fty;                                            \
 159     CONV_STOREB_##cty##_##fty;                                          \
 160     return (rc);                                                        \
 161   }
 162
 163 CONVERSIONS(DEF_CONV)
 164
 165 #undef DEF_CONV
 166
 167 /* --- @fltfmt_FTYEtoCTY@ --- *
 168  *
 169  * Arguments:   @float *z_out@, @double *z_out@ = storage for output
 170  *              @const octet *p@ = input pointer
 171  *              @unsigned r@ = rounding mode
 172  *
 173  * Returns:     Error flags (@FLTERR_...@).
 174  *
 175  * Use:         Decodes a floating point value in an external format into a
 176  *              native value.
 177  *
 178  *              The naming conventions are the same as for @fltfmt_dbltof64b@
 179  *              above.
 180  *
 181  *              On platforms where the external format is used natively,
 182  *              these functions are simple data copies.
 183  */
 184
 185 #define DEF_CONV(ctype, cty, fty)                                       \
 186   unsigned fltfmt_##fty##lto##cty(ctype *z_out, const octet *p, unsigned r) \
 187   {                                                                     \
 188     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 189                                                                         \
 190     CONV_LOADL_##cty##_##fty;                                           \
 191     CONV_FROB_##cty##_##fty;                                            \
 192     CONV_STORE_##cty##_##fty;                                           \
 193     return (rc);                                                        \
 194   }                                                                     \
 195                                                                         \
 196   unsigned fltfmt_##fty##bto##cty(ctype *z_out, const octet *p, unsigned r) \
 197   {                                                                     \
 198     unsigned rc = 0; CONV_DECLS_##cty##_##fty;                          \
 199                                                                         \
 200     CONV_LOADB_##cty##_##fty;                                           \
 201     CONV_FROB_##cty##_##fty;                                            \
 202     CONV_STORE_##cty##_##fty;                                           \
 203     return (rc);                                                        \
 204   }
 205
 206 CONVERSIONS(DEF_CONV)
 207
 208 #undef DEF_CONV
 209
 210 /*----- That's all, folks -------------------------------------------------*/