src/liblzma/lzma/lzma_literal.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       lzma_literal.c
   4 /// \brief      Literal Coder
   5 //
   6 //  Copyright (C) 1999-2006 Igor Pavlov
   7 //  Copyright (C) 2007 Lasse Collin
   8 //
   9 //  This library is free software; you can redistribute it and/or
  10 //  modify it under the terms of the GNU Lesser General Public
  11 //  License as published by the Free Software Foundation; either
  12 //  version 2.1 of the License, or (at your option) any later version.
  13 //
  14 //  This library is distributed in the hope that it will be useful,
  15 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17 //  Lesser General Public License for more details.
  18 //
  19 ///////////////////////////////////////////////////////////////////////////////
  20
  21 #include "lzma_literal.h"
  22
  23
  24 extern lzma_ret
  25 lzma_literal_init(lzma_literal_coder **coder, lzma_allocator *allocator,
  26                 uint32_t literal_context_bits, uint32_t literal_pos_bits)
  27 {
  28         // Verify that arguments are sane.
  29         if (literal_context_bits > LZMA_LITERAL_CONTEXT_BITS_MAX
  30                         || literal_pos_bits > LZMA_LITERAL_POS_BITS_MAX)
  31                 return LZMA_HEADER_ERROR;
  32
  33         // Calculate the number of states the literal coder must store.
  34         const uint32_t states = literal_states(
  35                         literal_pos_bits, literal_context_bits);
  36
  37         // Allocate a new literal coder, if needed.
  38         if (*coder == NULL || (**coder).literal_context_bits
  39                                 != literal_context_bits
  40                         || (**coder).literal_pos_bits != literal_pos_bits) {
  41                 // Free the old coder, if any.
  42                 lzma_free(*coder, allocator);
  43
  44                 // Allocate a new one.
  45                 *coder = lzma_alloc(sizeof(lzma_literal_coder)
  46                                 + states * LIT_SIZE * sizeof(probability),
  47                                 allocator);
  48                 if (*coder == NULL)
  49                         return LZMA_MEM_ERROR;
  50
  51                 // Store the new settings.
  52                 (**coder).literal_context_bits = literal_context_bits;
  53                 (**coder).literal_pos_bits = literal_pos_bits;
  54
  55                 // Calculate also the literal_pos_mask. It's not changed
  56                 // anywhere else than here.
  57                 (**coder).literal_pos_mask = (1 << literal_pos_bits) - 1;
  58         }
  59
  60         // Reset the literal coder.
  61         for (uint32_t i = 0; i < states; ++i)
  62                 for (uint32_t j = 0; j < LIT_SIZE; ++j)
  63                         bit_reset((**coder).coders[i][j]);
  64
  65         return LZMA_OK;
  66 }
  67
  68
  69 extern void
  70 lzma_literal_end(lzma_literal_coder **coder, lzma_allocator *allocator)
  71 {
  72         lzma_free(*coder, allocator);
  73         *coder = NULL;
  74 }