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/* Routines for restoring various data types from a file stream.  This deals

   with various data types like strings, integers, enums, etc.

   Copyright 2011 Free Software Foundation, Inc.

   Contributed by Diego Novillo <dnovillo@google.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "diagnostic.h"

#include "data-streamer.h"

/* Read a string from the string table in DATA_IN using input block

   IB.  Write the length to RLEN.  */

const char *

string_for_index (struct data_in *data_in, unsigned int loc, unsigned int *rlen)

{

  struct lto_input_block str_tab;

  unsigned int len;

  const char *result;

  if (!loc)

    {

      *rlen = 0;

      return NULL;

    }

  /* Get the string stored at location LOC in DATA_IN->STRINGS.  */

  LTO_INIT_INPUT_BLOCK (str_tab, data_in->strings, loc - 1,

                        data_in->strings_len);

  len = streamer_read_uhwi (&str_tab);

  *rlen = len;

  if (str_tab.p + len > data_in->strings_len)

    internal_error ("bytecode stream: string too long for the string table");

  result = (const char *)(data_in->strings + str_tab.p);

  return result;

}

/* Read a string from the string table in DATA_IN using input block

   IB.  Write the length to RLEN.  */

const char *

streamer_read_indexed_string (struct data_in *data_in,

                              struct lto_input_block *ib, unsigned int *rlen)

{

  return string_for_index (data_in, streamer_read_uhwi (ib), rlen);

}

/* Read a NULL terminated string from the string table in DATA_IN.  */

const char *

streamer_read_string (struct data_in *data_in, struct lto_input_block *ib)

{

  unsigned int len;

  const char *ptr;

  ptr = streamer_read_indexed_string (data_in, ib, &len);

  if (!ptr)

    return NULL;

  if (ptr[len - 1] != '\0')

    internal_error ("bytecode stream: found non-null terminated string");

  return ptr;

}

/* Read an unsigned HOST_WIDE_INT number from IB.  */

unsigned HOST_WIDE_INT

streamer_read_uhwi (struct lto_input_block *ib)

{

  unsigned HOST_WIDE_INT result = 0;

  int shift = 0;

  unsigned HOST_WIDE_INT byte;

  while (true)

    {

      byte = streamer_read_uchar (ib);

      result |= (byte & 0x7f) << shift;

      shift += 7;

      if ((byte & 0x80) == 0)

        return result;

    }

}

/* Read a HOST_WIDE_INT number from IB.  */

HOST_WIDE_INT

streamer_read_hwi (struct lto_input_block *ib)

{

  HOST_WIDE_INT result = 0;

  int shift = 0;

  unsigned HOST_WIDE_INT byte;

  while (true)

    {

      byte = streamer_read_uchar (ib);

      result |= (byte & 0x7f) << shift;

      shift += 7;

      if ((byte & 0x80) == 0)

        {

          if ((shift < HOST_BITS_PER_WIDE_INT) && (byte & 0x40))

            result |= - ((HOST_WIDE_INT)1 << shift);

          return result;

        }

    }

}