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///////////////////////////////////////////////////////////////////////////////
//
/// \file raw_common.c
/// \brief Stuff shared between raw encoder and raw decoder
//
// Copyright (C) 2007 Lasse Collin
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////
#include "raw_common.h"
/// \brief Prepares the filter chain
///
/// Prepares the filter chain by setting uncompressed sizes for each filter,
/// and adding implicit Subblock filter when needed.
///
/// \return true if error occurred, false on success.
///
static bool
prepare(lzma_vli *id, lzma_vli *uncompressed_size, bool implicit)
{
bool needs_end_of_input = false;
switch (id[0]) {
case LZMA_FILTER_COPY:
case LZMA_FILTER_X86:
case LZMA_FILTER_POWERPC:
case LZMA_FILTER_IA64:
case LZMA_FILTER_ARM:
case LZMA_FILTER_ARMTHUMB:
case LZMA_FILTER_SPARC:
case LZMA_FILTER_DELTA:
uncompressed_size[1] = uncompressed_size[0];
needs_end_of_input = true;
break;
case LZMA_FILTER_SUBBLOCK:
case LZMA_FILTER_LZMA:
// These change the size of the data unpredictably.
uncompressed_size[1] = LZMA_VLI_VALUE_UNKNOWN;
break;
case LZMA_FILTER_SUBBLOCK_HELPER:
uncompressed_size[1] = uncompressed_size[0];
break;
default:
// Unknown filter.
return true;
}
// Is this the last filter in the chain?
if (id[1] == LZMA_VLI_VALUE_UNKNOWN) {
if (!needs_end_of_input || !implicit || uncompressed_size[0]
!= LZMA_VLI_VALUE_UNKNOWN)
return false;
// Add implicit Subblock filter.
id[1] = LZMA_FILTER_SUBBLOCK;
uncompressed_size[1] = LZMA_VLI_VALUE_UNKNOWN;
id[2] = LZMA_VLI_VALUE_UNKNOWN;
}
return prepare(id + 1, uncompressed_size + 1, implicit);
}
extern lzma_ret
lzma_raw_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
const lzma_options_filter *options, lzma_vli uncompressed_size,
lzma_init_function (*get_function)(lzma_vli id),
bool allow_implicit, bool is_encoder)
{
if (options == NULL || !lzma_vli_is_valid(uncompressed_size))
return LZMA_PROG_ERROR;
// Count the number of filters in the chain.
size_t count = 0;
while (options[count].id != LZMA_VLI_VALUE_UNKNOWN)
++count;
// Allocate enough space from the stack for IDs and uncompressed
// sizes. We need two extra: possible implicit Subblock and end
// of array indicator.
lzma_vli ids[count + 2];
lzma_vli uncompressed_sizes[count + 2];
bool using_implicit = false;
uncompressed_sizes[0] = uncompressed_size;
if (count == 0) {
if (!allow_implicit)
return LZMA_PROG_ERROR;
count = 1;
using_implicit = true;
// Special case: no filters were specified, so an implicit
// Copy or Subblock filter is used.
if (uncompressed_size == LZMA_VLI_VALUE_UNKNOWN)
ids[0] = LZMA_FILTER_SUBBLOCK;
else
ids[0] = LZMA_FILTER_COPY;
ids[1] = LZMA_VLI_VALUE_UNKNOWN;
} else {
// Prepare the ids[] and uncompressed_sizes[].
for (size_t i = 0; i < count; ++i)
ids[i] = options[i].id;
ids[count] = LZMA_VLI_VALUE_UNKNOWN;
if (prepare(ids, uncompressed_sizes, allow_implicit))
return LZMA_HEADER_ERROR;
// Check if implicit Subblock filter was added.
if (ids[count] != LZMA_VLI_VALUE_UNKNOWN) {
assert(ids[count] == LZMA_FILTER_SUBBLOCK);
++count;
using_implicit = true;
}
}
// Set the filter functions, and copy uncompressed sizes and options.
lzma_filter_info filters[count + 1];
if (is_encoder) {
for (size_t i = 0; i < count; ++i) {
// The order of the filters is reversed in the
// encoder. It allows more efficient handling
// of the uncompressed data.
const size_t j = count - i - 1;
filters[j].init = get_function(ids[i]);
if (filters[j].init == NULL)
return LZMA_HEADER_ERROR;
filters[j].options = options[i].options;
filters[j].uncompressed_size = uncompressed_sizes[i];
}
if (using_implicit)
filters[0].options = NULL;
} else {
for (size_t i = 0; i < count; ++i) {
filters[i].init = get_function(ids[i]);
if (filters[i].init == NULL)
return LZMA_HEADER_ERROR;
filters[i].options = options[i].options;
filters[i].uncompressed_size = uncompressed_sizes[i];
}
if (using_implicit)
filters[count - 1].options = NULL;
}
// Terminate the array.
filters[count].init = NULL;
// Initialize the filters.
return lzma_next_filter_init(next, allocator, filters);
}
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