external/bsd/tcpdump/dist/extract.h

   1 /*
   2  * Copyright (c) 1992, 1993, 1994, 1995, 1996
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 #ifdef __NetBSD__
  23 #include <string.h>
  24
  25 /*
  26  * Do it the portable way and let the compiler optimize the code
  27  */
  28 static inline uint16_t EXTRACT_16BITS(const void *p)
  29 {
  30         uint16_t t;
  31         memcpy(&t, p, sizeof(t));
  32         return ntohs(t);
  33 }
  34
  35 static inline uint32_t EXTRACT_24BITS(const void *p)
  36 {
  37         uint8_t t[3];
  38         memcpy(t, p, sizeof(t));
  39         return
  40             ((uint32_t)t[0] << 16) |
  41             ((uint32_t)t[1] << 8) |
  42             t[2];
  43 }
  44
  45 static inline uint32_t EXTRACT_32BITS(const void *p)
  46 {
  47         uint32_t t;
  48         memcpy(&t, p, sizeof(t));
  49         return ntohl(t);
  50 }
  51
  52
  53 static inline uint64_t EXTRACT_48BITS(const void *p)
  54 {
  55         uint8_t t[6];
  56         memcpy(t, p, sizeof(t));
  57         return
  58             ((uint64_t)t[0] << 40) |
  59             ((uint64_t)t[1] << 32) |
  60             ((uint64_t)t[2] << 24) |
  61             ((uint64_t)t[3] << 16) |
  62             ((uint64_t)t[4] <<  8) |
  63             t[5];
  64 }
  65
  66 static inline uint64_t EXTRACT_64BITS(const void *p)
  67 {
  68         uint32_t t[2];
  69         memcpy(&t[0], p, sizeof(t[0]));
  70         memcpy(&t[1], (const uint8_t *)p + sizeof(t[0]), sizeof(t[1]));
  71         return ((uint64_t)ntohl(t[0]) << 32) | ntohl(t[1]);
  72 }
  73
  74 static inline uint8_t EXTRACT_LE_8BITS(const void *p)
  75 {
  76         uint8_t t[1];
  77         memcpy(t, p, sizeof(t));
  78         return t[0];
  79 }
  80
  81 static inline uint16_t EXTRACT_LE_16BITS(const void *p)
  82 {
  83         uint8_t t[2];
  84         memcpy(t, p, sizeof(t));
  85         return
  86             ((uint16_t)t[1] << 8) |
  87             t[0];
  88 }
  89
  90 static inline uint32_t EXTRACT_LE_24BITS(const void *p)
  91 {
  92         uint8_t t[3];
  93         memcpy(t, p, sizeof(t));
  94         return
  95             ((uint32_t)t[2] << 16) |
  96             ((uint32_t)t[1] << 8) |
  97             t[0];
  98 }
  99
 100 static inline uint32_t EXTRACT_LE_32BITS(const void *p)
 101 {
 102         uint8_t t[4];
 103         memcpy(t, p, sizeof(t));
 104         return
 105             ((uint32_t)t[3] << 24) |
 106             ((uint32_t)t[2] << 16) |
 107             ((uint32_t)t[1] << 8) |
 108             t[0];
 109 }
 110
 111 static inline uint64_t EXTRACT_LE_64BITS(const void *p)
 112 {
 113         uint8_t t[8];
 114         memcpy(&t, p, sizeof(t));
 115         return
 116             ((uint64_t)t[7] << 56) |
 117             ((uint64_t)t[6] << 48) |
 118             ((uint64_t)t[5] << 40) |
 119             ((uint64_t)t[4] << 32) |
 120             ((uint64_t)t[3] << 24) |
 121             ((uint64_t)t[2] << 16) |
 122             ((uint64_t)t[1] << 8) |
 123             t[0];
 124 }
 125
 126 #else /* Fast & Loose */
 127 /*
 128  * Macros to extract possibly-unaligned big-endian integral values.
 129  */
 130 #ifdef LBL_ALIGN
 131 /*
 132  * The processor doesn't natively handle unaligned loads.
 133  */
 134 #if defined(__GNUC__) && defined(HAVE___ATTRIBUTE__) && \
 135     (defined(__alpha) || defined(__alpha__) || \
 136      defined(__mips) || defined(__mips__))
 137
 138 /*
 139  * This is a GCC-compatible compiler and we have __attribute__, which
 140  * we assume that mean we have __attribute__((packed)), and this is
 141  * MIPS or Alpha, which has instructions that can help when doing
 142  * unaligned loads.
 143  *
 144  * Declare packed structures containing a uint16_t and a uint32_t,
 145  * cast the pointer to point to one of those, and fetch through it;
 146  * the GCC manual doesn't appear to explicitly say that
 147  * __attribute__((packed)) causes the compiler to generate unaligned-safe
 148  * code, but it apppears to do so.
 149  *
 150  * We do this in case the compiler can generate code using those
 151  * instructions to do an unaligned load and pass stuff to "ntohs()" or
 152  * "ntohl()", which might be better than than the code to fetch the
 153  * bytes one at a time and assemble them.  (That might not be the
 154  * case on a little-endian platform, such as DEC's MIPS machines and
 155  * Alpha machines, where "ntohs()" and "ntohl()" might not be done
 156  * inline.)
 157  *
 158  * We do this only for specific architectures because, for example,
 159  * at least some versions of GCC, when compiling for 64-bit SPARC,
 160  * generate code that assumes alignment if we do this.
 161  *
 162  * XXX - add other architectures and compilers as possible and
 163  * appropriate.
 164  *
 165  * HP's C compiler, indicated by __HP_cc being defined, supports
 166  * "#pragma unaligned N" in version A.05.50 and later, where "N"
 167  * specifies a number of bytes at which the typedef on the next
 168  * line is aligned, e.g.
 169  *
 170  *      #pragma unalign 1
 171  *      typedef uint16_t unaligned_uint16_t;
 172  *
 173  * to define unaligned_uint16_t as a 16-bit unaligned data type.
 174  * This could be presumably used, in sufficiently recent versions of
 175  * the compiler, with macros similar to those below.  This would be
 176  * useful only if that compiler could generate better code for PA-RISC
 177  * or Itanium than would be generated by a bunch of shifts-and-ORs.
 178  *
 179  * DEC C, indicated by __DECC being defined, has, at least on Alpha,
 180  * an __unaligned qualifier that can be applied to pointers to get the
 181  * compiler to generate code that does unaligned loads and stores when
 182  * dereferencing the pointer in question.
 183  *
 184  * XXX - what if the native C compiler doesn't support
 185  * __attribute__((packed))?  How can we get it to generate unaligned
 186  * accesses for *specific* items?
 187  */
 188 typedef struct {
 189         uint16_t        val;
 190 } __attribute__((packed)) unaligned_uint16_t;
 191
 192 typedef struct {
 193         uint32_t        val;
 194 } __attribute__((packed)) unaligned_uint32_t;
 195
 196 static inline uint16_t
 197 EXTRACT_16BITS(const void *p)
 198 {
 199         return ((uint16_t)ntohs(((const unaligned_uint16_t *)(p))->val));
 200 }
 201
 202 static inline uint32_t
 203 EXTRACT_32BITS(const void *p)
 204 {
 205         return ((uint32_t)ntohl(((const unaligned_uint32_t *)(p))->val));
 206 }
 207
 208 static inline uint64_t
 209 EXTRACT_64BITS(const void *p)
 210 {
 211         return ((uint64_t)(((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 0)->val)) << 32 | \
 212                 ((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 1)->val)) << 0));
 213 }
 214
 215 #else /* have to do it a byte at a time */
 216 /*
 217  * This isn't a GCC-compatible compiler, we don't have __attribute__,
 218  * or we do but we don't know of any better way with this instruction
 219  * set to do unaligned loads, so do unaligned loads of big-endian
 220  * quantities the hard way - fetch the bytes one at a time and
 221  * assemble them.
 222  */
 223 #define EXTRACT_16BITS(p) \
 224         ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 0)) << 8) | \
 225                     ((uint16_t)(*((const uint8_t *)(p) + 1)) << 0)))
 226 #define EXTRACT_32BITS(p) \
 227         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 24) | \
 228                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 16) | \
 229                     ((uint32_t)(*((const uint8_t *)(p) + 2)) << 8) | \
 230                     ((uint32_t)(*((const uint8_t *)(p) + 3)) << 0)))
 231 #define EXTRACT_64BITS(p) \
 232         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 56) | \
 233                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 48) | \
 234                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 40) | \
 235                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 32) | \
 236                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 24) | \
 237                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 16) | \
 238                     ((uint64_t)(*((const uint8_t *)(p) + 6)) << 8) | \
 239                     ((uint64_t)(*((const uint8_t *)(p) + 7)) << 0)))
 240 #endif /* must special-case unaligned accesses */
 241 #else /* LBL_ALIGN */
 242 /*
 243  * The processor natively handles unaligned loads, so we can just
 244  * cast the pointer and fetch through it.
 245  */
 246 static inline uint16_t
 247 EXTRACT_16BITS(const void *p)
 248 {
 249         return ((uint16_t)ntohs(*(const uint16_t *)(p)));
 250 }
 251
 252 static inline uint32_t
 253 EXTRACT_32BITS(const void *p)
 254 {
 255         return ((uint32_t)ntohl(*(const uint32_t *)(p)));
 256 }
 257
 258 static inline uint64_t
 259 EXTRACT_64BITS(const void *p)
 260 {
 261         return ((uint64_t)(((uint64_t)ntohl(*((const uint32_t *)(p) + 0))) << 32 | \
 262                 ((uint64_t)ntohl(*((const uint32_t *)(p) + 1))) << 0));
 263
 264 }
 265
 266 #endif /* LBL_ALIGN */
 267
 268 #define EXTRACT_24BITS(p) \
 269         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 16) | \
 270                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 271                     ((uint32_t)(*((const uint8_t *)(p) + 2)) << 0)))
 272
 273 #define EXTRACT_40BITS(p) \
 274         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 32) | \
 275                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 24) | \
 276                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 277                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 8) | \
 278                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 0)))
 279
 280 #define EXTRACT_48BITS(p) \
 281         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 40) | \
 282                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 32) | \
 283                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 24) | \
 284                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 16) | \
 285                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 8) | \
 286                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 0)))
 287
 288 #define EXTRACT_56BITS(p) \
 289         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 48) | \
 290                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 40) | \
 291                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 32) | \
 292                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \
 293                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 16) | \
 294                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 8) | \
 295                     ((uint64_t)(*((const uint8_t *)(p) + 6)) << 0)))
 296
 297 /*
 298  * Macros to extract possibly-unaligned little-endian integral values.
 299  * XXX - do loads on little-endian machines that support unaligned loads?
 300  */
 301 #define EXTRACT_LE_8BITS(p) (*(p))
 302 #define EXTRACT_LE_16BITS(p) \
 303         ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 304                     ((uint16_t)(*((const uint8_t *)(p) + 0)) << 0)))
 305 #define EXTRACT_LE_32BITS(p) \
 306         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 3)) << 24) | \
 307                     ((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 308                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 309                     ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0)))
 310 #define EXTRACT_LE_24BITS(p) \
 311         ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 312                     ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 313                     ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0)))
 314 #define EXTRACT_LE_64BITS(p) \
 315         ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 7)) << 56) | \
 316                     ((uint64_t)(*((const uint8_t *)(p) + 6)) << 48) | \
 317                     ((uint64_t)(*((const uint8_t *)(p) + 5)) << 40) | \
 318                     ((uint64_t)(*((const uint8_t *)(p) + 4)) << 32) | \
 319                     ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \
 320                     ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \
 321                     ((uint64_t)(*((const uint8_t *)(p) + 1)) << 8) | \
 322                     ((uint64_t)(*((const uint8_t *)(p) + 0)) << 0)))
 323 #endif /* __NetBSD__ */