gcc/data-streamer.c

   1 /* Generic streaming support for basic data types.
   2
   3    Copyright (C) 2011-2013 Free Software Foundation, Inc.
   4    Contributed by Diego Novillo <dnovillo@google.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "data-streamer.h"
  26
  27 /* Pack WORK into BP in a variant of uleb format.  */
  28
  29 void
  30 bp_pack_var_len_unsigned (struct bitpack_d *bp, unsigned HOST_WIDE_INT work)
  31 {
  32   do
  33     {
  34       unsigned int half_byte = (work & 0x7);
  35       work >>= 3;
  36       if (work != 0)
  37         /* More half_bytes to follow.  */
  38         half_byte |= 0x8;
  39
  40       bp_pack_value (bp, half_byte, 4);
  41     }
  42   while (work != 0);
  43 }
  44
  45
  46 /* Pack WORK into BP in a variant of sleb format.  */
  47
  48 void
  49 bp_pack_var_len_int (struct bitpack_d *bp, HOST_WIDE_INT work)
  50 {
  51   int more, half_byte;
  52
  53   do
  54     {
  55       half_byte = (work & 0x7);
  56       /* arithmetic shift */
  57       work >>= 3;
  58       more = !((work == 0 && (half_byte & 0x4) == 0)
  59                || (work == -1 && (half_byte & 0x4) != 0));
  60       if (more)
  61         half_byte |= 0x8;
  62
  63       bp_pack_value (bp, half_byte, 4);
  64     }
  65   while (more);
  66 }
  67
  68
  69 /* Unpack VAL from BP in a variant of uleb format.  */
  70
  71 unsigned HOST_WIDE_INT
  72 bp_unpack_var_len_unsigned (struct bitpack_d *bp)
  73 {
  74   unsigned HOST_WIDE_INT result = 0;
  75   int shift = 0;
  76   unsigned HOST_WIDE_INT half_byte;
  77
  78   while (true)
  79     {
  80       half_byte = bp_unpack_value (bp, 4);
  81       result |= (half_byte & 0x7) << shift;
  82       shift += 3;
  83       if ((half_byte & 0x8) == 0)
  84         return result;
  85     }
  86 }
  87
  88
  89 /* Unpack VAL from BP in a variant of sleb format.  */
  90
  91 HOST_WIDE_INT
  92 bp_unpack_var_len_int (struct bitpack_d *bp)
  93 {
  94   HOST_WIDE_INT result = 0;
  95   int shift = 0;
  96   unsigned HOST_WIDE_INT half_byte;
  97
  98   while (true)
  99     {
 100       half_byte = bp_unpack_value (bp, 4);
 101       result |= (half_byte & 0x7) << shift;
 102       shift += 3;
 103       if ((half_byte & 0x8) == 0)
 104         {
 105           if ((shift < HOST_BITS_PER_WIDE_INT) && (half_byte & 0x4))
 106             result |= - ((HOST_WIDE_INT)1 << shift);
 107
 108           return result;
 109         }
 110     }
 111 }