formats/ctf/types/float.c

   1 /*
   2  * Common Trace Format
   3  *
   4  * Floating point read/write functions.
   5  *
   6  * Copyright 2010-2011 EfficiOS Inc. and Linux Foundation
   7  *
   8  * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * Reference: ISO C99 standard 5.2.4
  21  */
  22
  23 #include <babeltrace/ctf/types.h>
  24 #include <glib.h>
  25 #include <float.h>      /* C99 floating point definitions */
  26 #include <limits.h>     /* C99 limits */
  27 #include <babeltrace/endian.h>
  28 #include <pthread.h>
  29
  30 /*
  31  * This library is limited to binary representation of floating point values.
  32  * We use hardware support for conversion between 32 and 64-bit floating
  33  * point values.
  34  */
  35
  36 /*
  37  * Aliasing float/double and unsigned long is not strictly permitted by strict
  38  * aliasing, but in practice declaration prunning is well supported, and this permits
  39  * us to use per-word read/writes rather than per-byte.
  40  */
  41
  42 #if defined(__GNUC__) || defined(__MINGW32__) || defined(_MSC_VER)
  43 #define HAS_TYPE_PRUNING
  44 #endif
  45
  46 #if (FLT_RADIX != 2)
  47
  48 #error "Unsupported floating point radix"
  49
  50 #endif
  51
  52 union doubleIEEE754 {
  53         double vd;
  54         float vf;
  55 #ifdef HAS_TYPE_PRUNING
  56         unsigned long bits[(sizeof(double) + sizeof(unsigned long) - 1) / sizeof(unsigned long)];
  57 #else
  58         unsigned char bits[sizeof(double)];
  59 #endif
  60 };
  61
  62 /*
  63  * This mutex protects the static temporary float and double
  64  * declarations (static_float_declaration and static_double_declaration).
  65  */
  66 static pthread_mutex_t float_mutex = PTHREAD_MUTEX_INITIALIZER;
  67
  68 static struct declaration_float *static_float_declaration,
  69                 *static_double_declaration;
  70
  71 struct pos_len {
  72         size_t len;
  73 };
  74
  75 static void float_lock(void)
  76 {
  77         int ret;
  78
  79         ret = pthread_mutex_lock(&float_mutex);
  80         assert(!ret);
  81 }
  82
  83 static void float_unlock(void)
  84 {
  85         int ret;
  86
  87         ret = pthread_mutex_unlock(&float_mutex);
  88         assert(!ret);
  89 }
  90
  91 int _ctf_float_copy(struct stream_pos *destp,
  92                     struct definition_float *dest_definition,
  93                     struct stream_pos *srcp,
  94                     const struct definition_float *src_definition)
  95 {
  96         int ret;
  97
  98         /* We only support copy of same-size floats for now */
  99         assert(src_definition->declaration->sign->len ==
 100                 dest_definition->declaration->sign->len);
 101         assert(src_definition->declaration->exp->len ==
 102                 dest_definition->declaration->exp->len);
 103         assert(src_definition->declaration->mantissa->len ==
 104                 dest_definition->declaration->mantissa->len);
 105         /* Read */
 106         if (src_definition->declaration->byte_order == LITTLE_ENDIAN) {
 107                 ret = ctf_integer_read(srcp, &src_definition->mantissa->p);
 108                 if (ret)
 109                         return ret;
 110                 ret = ctf_integer_read(srcp, &src_definition->exp->p);
 111                 if (ret)
 112                         return ret;
 113                 ret = ctf_integer_read(srcp, &src_definition->sign->p);
 114                 if (ret)
 115                         return ret;
 116         } else {
 117                 ret = ctf_integer_read(srcp, &src_definition->sign->p);
 118                 if (ret)
 119                         return ret;
 120                 ret = ctf_integer_read(srcp, &src_definition->exp->p);
 121                 if (ret)
 122                         return ret;
 123                 ret = ctf_integer_read(srcp, &src_definition->mantissa->p);
 124                 if (ret)
 125                         return ret;
 126         }
 127
 128         dest_definition->mantissa->value._unsigned =
 129                 src_definition->mantissa->value._unsigned;
 130         dest_definition->exp->value._signed =
 131                 src_definition->exp->value._signed;
 132         dest_definition->sign->value._unsigned =
 133                 src_definition->sign->value._unsigned;
 134
 135         /* Write */
 136         if (dest_definition->declaration->byte_order == LITTLE_ENDIAN) {
 137                 ret = ctf_integer_write(destp, &dest_definition->mantissa->p);
 138                 if (ret)
 139                         return ret;
 140                 ret = ctf_integer_write(destp, &dest_definition->exp->p);
 141                 if (ret)
 142                         return ret;
 143                 ret = ctf_integer_write(destp, &dest_definition->sign->p);
 144                 if (ret)
 145                         return ret;
 146         } else {
 147                 ret = ctf_integer_write(destp, &dest_definition->sign->p);
 148                 if (ret)
 149                         return ret;
 150                 ret = ctf_integer_write(destp, &dest_definition->exp->p);
 151                 if (ret)
 152                         return ret;
 153                 ret = ctf_integer_write(destp, &dest_definition->mantissa->p);
 154                 if (ret)
 155                         return ret;
 156         }
 157         return 0;
 158 }
 159
 160 int ctf_float_read(struct stream_pos *ppos, struct definition *definition)
 161 {
 162         struct definition_float *float_definition =
 163                 container_of(definition, struct definition_float, p);
 164         const struct declaration_float *float_declaration =
 165                 float_definition->declaration;
 166         struct ctf_stream_pos *pos = ctf_pos(ppos);
 167         union doubleIEEE754 u;
 168         struct definition *tmpdef;
 169         struct definition_float *tmpfloat;
 170         struct ctf_stream_pos destp;
 171         struct mmap_align mma;
 172         int ret;
 173
 174         float_lock();
 175         switch (float_declaration->mantissa->len + 1) {
 176         case FLT_MANT_DIG:
 177                 tmpdef = static_float_declaration->p.definition_new(
 178                                 &static_float_declaration->p,
 179                                 NULL, 0, 0, "__tmpfloat");
 180                 break;
 181         case DBL_MANT_DIG:
 182                 tmpdef = static_double_declaration->p.definition_new(
 183                                 &static_double_declaration->p,
 184                                 NULL, 0, 0, "__tmpfloat");
 185                 break;
 186         default:
 187                 ret = -EINVAL;
 188                 goto end;
 189         }
 190         tmpfloat = container_of(tmpdef, struct definition_float, p);
 191         memset(&destp, 0, sizeof(destp));
 192         ctf_init_pos(&destp, -1, O_RDWR);
 193         mmap_align_set_addr(&mma, (char *) u.bits);
 194         destp.base_mma = &mma;
 195         destp.packet_size = sizeof(u) * CHAR_BIT;
 196         ctf_align_pos(pos, float_declaration->p.alignment);
 197         ret = _ctf_float_copy(&destp.parent, tmpfloat, ppos, float_definition);
 198         switch (float_declaration->mantissa->len + 1) {
 199         case FLT_MANT_DIG:
 200                 float_definition->value = u.vf;
 201                 break;
 202         case DBL_MANT_DIG:
 203                 float_definition->value = u.vd;
 204                 break;
 205         default:
 206                 ret = -EINVAL;
 207                 goto end_unref;
 208         }
 209
 210 end_unref:
 211         definition_unref(tmpdef);
 212 end:
 213         float_unlock();
 214         return ret;
 215 }
 216
 217 int ctf_float_write(struct stream_pos *ppos, struct definition *definition)
 218 {
 219         struct definition_float *float_definition =
 220                 container_of(definition, struct definition_float, p);
 221         const struct declaration_float *float_declaration =
 222                 float_definition->declaration;
 223         struct ctf_stream_pos *pos = ctf_pos(ppos);
 224         union doubleIEEE754 u;
 225         struct definition *tmpdef;
 226         struct definition_float *tmpfloat;
 227         struct ctf_stream_pos srcp;
 228         struct mmap_align mma;
 229         int ret;
 230
 231         float_lock();
 232         switch (float_declaration->mantissa->len + 1) {
 233         case FLT_MANT_DIG:
 234                 tmpdef = static_float_declaration->p.definition_new(
 235                                 &static_float_declaration->p,
 236                                 NULL, 0, 0, "__tmpfloat");
 237                 break;
 238         case DBL_MANT_DIG:
 239                 tmpdef = static_double_declaration->p.definition_new(
 240                                 &static_double_declaration->p,
 241                                 NULL, 0, 0, "__tmpfloat");
 242                 break;
 243         default:
 244                 ret = -EINVAL;
 245                 goto end;
 246         }
 247         tmpfloat = container_of(tmpdef, struct definition_float, p);
 248         ctf_init_pos(&srcp, -1, O_RDONLY);
 249         mmap_align_set_addr(&mma, (char *) u.bits);
 250         srcp.base_mma = &mma;
 251         srcp.packet_size = sizeof(u) * CHAR_BIT;
 252         switch (float_declaration->mantissa->len + 1) {
 253         case FLT_MANT_DIG:
 254                 u.vf = float_definition->value;
 255                 break;
 256         case DBL_MANT_DIG:
 257                 u.vd = float_definition->value;
 258                 break;
 259         default:
 260                 ret = -EINVAL;
 261                 goto end_unref;
 262         }
 263         ctf_align_pos(pos, float_declaration->p.alignment);
 264         ret = _ctf_float_copy(ppos, float_definition, &srcp.parent, tmpfloat);
 265
 266 end_unref:
 267         definition_unref(tmpdef);
 268 end:
 269         float_unlock();
 270         return ret;
 271 }
 272
 273 void __attribute__((constructor)) ctf_float_init(void)
 274 {
 275         static_float_declaration =
 276                 float_declaration_new(FLT_MANT_DIG,
 277                                 sizeof(float) * CHAR_BIT - FLT_MANT_DIG,
 278                                 BYTE_ORDER,
 279                                 __alignof__(float));
 280         static_double_declaration =
 281                 float_declaration_new(DBL_MANT_DIG,
 282                                 sizeof(double) * CHAR_BIT - DBL_MANT_DIG,
 283                                 BYTE_ORDER,
 284                                 __alignof__(double));
 285 }
 286
 287 void __attribute__((destructor)) ctf_float_fini(void)
 288 {
 289         declaration_unref(&static_float_declaration->p);
 290         declaration_unref(&static_double_declaration->p);
 291 }