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 "tree.h"
  26 #include "data-streamer.h"
  27
  28 /* Pack WORK into BP in a variant of uleb format.  */
  29
  30 void
  31 bp_pack_var_len_unsigned (struct bitpack_d *bp, unsigned HOST_WIDE_INT work)
  32 {
  33   do
  34     {
  35       unsigned int half_byte = (work & 0x7);
  36       work >>= 3;
  37       if (work != 0)
  38         /* More half_bytes to follow.  */
  39         half_byte |= 0x8;
  40
  41       bp_pack_value (bp, half_byte, 4);
  42     }
  43   while (work != 0);
  44 }
  45
  46
  47 /* Pack WORK into BP in a variant of sleb format.  */
  48
  49 void
  50 bp_pack_var_len_int (struct bitpack_d *bp, HOST_WIDE_INT work)
  51 {
  52   int more, half_byte;
  53
  54   do
  55     {
  56       half_byte = (work & 0x7);
  57       /* arithmetic shift */
  58       work >>= 3;
  59       more = !((work == 0 && (half_byte & 0x4) == 0)
  60                || (work == -1 && (half_byte & 0x4) != 0));
  61       if (more)
  62         half_byte |= 0x8;
  63
  64       bp_pack_value (bp, half_byte, 4);
  65     }
  66   while (more);
  67 }
  68
  69
  70 /* Unpack VAL from BP in a variant of uleb format.  */
  71
  72 unsigned HOST_WIDE_INT
  73 bp_unpack_var_len_unsigned (struct bitpack_d *bp)
  74 {
  75   unsigned HOST_WIDE_INT result = 0;
  76   int shift = 0;
  77   unsigned HOST_WIDE_INT half_byte;
  78
  79   while (true)
  80     {
  81       half_byte = bp_unpack_value (bp, 4);
  82       result |= (half_byte & 0x7) << shift;
  83       shift += 3;
  84       if ((half_byte & 0x8) == 0)
  85         return result;
  86     }
  87 }
  88
  89
  90 /* Unpack VAL from BP in a variant of sleb format.  */
  91
  92 HOST_WIDE_INT
  93 bp_unpack_var_len_int (struct bitpack_d *bp)
  94 {
  95   HOST_WIDE_INT result = 0;
  96   int shift = 0;
  97   unsigned HOST_WIDE_INT half_byte;
  98
  99   while (true)
 100     {
 101       half_byte = bp_unpack_value (bp, 4);
 102       result |= (half_byte & 0x7) << shift;
 103       shift += 3;
 104       if ((half_byte & 0x8) == 0)
 105         {
 106           if ((shift < HOST_BITS_PER_WIDE_INT) && (half_byte & 0x4))
 107             result |= - ((HOST_WIDE_INT)1 << shift);
 108
 109           return result;
 110         }
 111     }
 112 }