src/pack.c

   1 /*
   2  * Copyright © 2009 Nick Bowler
   3  *
   4  * Portable binary (de-)serialisation of integral types.
   5  *
   6  * License WTFPL2: Do What The Fuck You Want To Public License, version 2.
   7  * This is free software: you are free to do what the fuck you want to.
   8  * There is NO WARRANTY, to the extent permitted by law.
   9  */
  10
  11 #include "pack.h"
  12
  13 /* Unsigned integer packing. */
  14 #define DEFPACK_BE(bits, type) void pack_ ## bits ## _be ( \
  15         unsigned char *out, type v \
  16 ) { \
  17         unsigned i; \
  18         for (i = 1; i <= bits/8; i++) { \
  19                 out[bits/8 - i] = v % 256; \
  20                 v /= 256; \
  21         } \
  22 }
  23
  24 #define DEFPACK_LE(bits, type) void pack_ ## bits ## _le ( \
  25         unsigned char *out, type v \
  26 ) { \
  27         unsigned i; \
  28         for (i = 0; i < bits/8; i++) { \
  29                 out[i] = v % 256; \
  30                 v /= 256; \
  31         } \
  32 }
  33
  34 DEFPACK_BE(16, unsigned short)
  35 DEFPACK_BE(32, unsigned long)
  36 #if PACK_HAVE_64BIT
  37 DEFPACK_BE(64, unsigned long long)
  38 #endif
  39
  40 DEFPACK_LE(16, unsigned short)
  41 DEFPACK_LE(32, unsigned long)
  42 #if PACK_HAVE_64BIT
  43 DEFPACK_LE(64, unsigned long long)
  44 #endif
  45
  46 #define DEFUNPACK_BE(bits, type) type unpack_ ## bits ## _be ( \
  47         const unsigned char *in \
  48 ) { \
  49         type v = 0; \
  50         unsigned i; \
  51         for (i = 0; i < bits/8; i++) { \
  52                 v *= 256; \
  53                 v += in[i]; \
  54         } \
  55         return v; \
  56 }
  57
  58 #define DEFUNPACK_LE(bits, type) type unpack_ ## bits ## _le ( \
  59         const unsigned char *in \
  60 ) { \
  61         type v = 0; \
  62         unsigned i; \
  63         for (i = 1; i <= bits/8; i++) { \
  64                 v *= 256; \
  65                 v += in[bits/8 - i]; \
  66         } \
  67         return v; \
  68 }
  69
  70 DEFUNPACK_BE(16, unsigned short)
  71 DEFUNPACK_BE(32, unsigned long)
  72 #if PACK_HAVE_64BIT
  73 DEFUNPACK_BE(64, unsigned long long)
  74 #endif
  75
  76 DEFUNPACK_LE(16, unsigned short)
  77 DEFUNPACK_LE(32, unsigned long)
  78 #if PACK_HAVE_64BIT
  79 DEFUNPACK_LE(64, unsigned long long)
  80 #endif
  81
  82 /*
  83  * Two's complement signed integer packing.  This is unlikely to work on
  84  * systems that don't themselves use two's complement.
  85  */
  86
  87 #define DEFUNPACK_SBE(bits, max, type) type unpack_s ## bits ## _be ( \
  88         const unsigned char *in \
  89 ) { \
  90         type v = 0; \
  91         unsigned i; \
  92         int sign = (in[0] & 0x80) ? 1 : 0; \
  93         for (i = 0; i < bits/8; i++) { \
  94                 v *= 256; \
  95                 v += in[i] & (i == 0 ? 0x7f : 0xff); \
  96         } \
  97         return sign*(-max-1) + v; \
  98 }
  99
 100 #define DEFUNPACK_SLE(bits, max, type) type unpack_s ## bits ## _le ( \
 101         const unsigned char *in \
 102 ) { \
 103         type v = 0; \
 104         unsigned i; \
 105         int sign = (in[bits/8 - 1] & 0x80) ? 1 : 0; \
 106         for (i = 1; i <= bits/8; i++) { \
 107                 v *= 256; \
 108                 v += in[bits/8 - i] & (i == 1 ? 0x7f : 0xff); \
 109         } \
 110         return sign*(-max-1) + v; \
 111 }
 112
 113 DEFUNPACK_SBE(16, 32767, short)
 114 DEFUNPACK_SBE(32, 2147483647l, long)
 115 #if PACK_HAVE_64BIT
 116 DEFUNPACK_SBE(64, 9223372036854775807ll, long long)
 117 #endif
 118
 119 DEFUNPACK_SLE(16, 32767, short)
 120 DEFUNPACK_SLE(32, 2147483647l, long)
 121 #if PACK_HAVE_64BIT
 122 DEFUNPACK_SLE(64, 9223372036854775807ll, long long)
 123 #endif