284 lines
8.2 KiB
C
284 lines
8.2 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file simple_coder.c
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/// \brief Wrapper for simple filters
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///
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/// Simple filters don't change the size of the data i.e. number of bytes
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/// in equals the number of bytes out.
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//
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// Author: Lasse Collin
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "simple_private.h"
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/// Copied or encodes/decodes more data to out[].
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static lzma_ret
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copy_or_code(lzma_coder *coder, lzma_allocator *allocator,
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const uint8_t *LZMA_RESTRICT in, size_t *LZMA_RESTRICT in_pos,
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size_t in_size, uint8_t *LZMA_RESTRICT out,
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size_t *LZMA_RESTRICT out_pos, size_t out_size, lzma_action action)
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{
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assert(!coder->end_was_reached);
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if (coder->next.code == NULL) {
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lzma_bufcpy(in, in_pos, in_size, out, out_pos, out_size);
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// Check if end of stream was reached.
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if (coder->is_encoder && action == LZMA_FINISH
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&& *in_pos == in_size)
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coder->end_was_reached = true;
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} else {
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// Call the next coder in the chain to provide us some data.
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const lzma_ret ret = coder->next.code(
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coder->next.coder, allocator,
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in, in_pos, in_size,
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out, out_pos, out_size, action);
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if (ret == LZMA_STREAM_END) {
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assert(!coder->is_encoder
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|| action == LZMA_FINISH);
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coder->end_was_reached = true;
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} else if (ret != LZMA_OK) {
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return ret;
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}
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}
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return LZMA_OK;
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}
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static size_t
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call_filter(lzma_coder *coder, uint8_t *buffer, size_t size)
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{
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const size_t filtered = coder->filter(coder->simple,
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coder->now_pos, coder->is_encoder,
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buffer, size);
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coder->now_pos += filtered;
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return filtered;
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}
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static lzma_ret
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simple_code(lzma_coder *coder, lzma_allocator *allocator,
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const uint8_t *LZMA_RESTRICT in, size_t *LZMA_RESTRICT in_pos,
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size_t in_size, uint8_t *LZMA_RESTRICT out,
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size_t *LZMA_RESTRICT out_pos, size_t out_size, lzma_action action)
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{
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size_t out_avail;
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size_t buf_avail;
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// TODO: Add partial support for LZMA_SYNC_FLUSH. We can support it
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// in cases when the filter is able to filter everything. With most
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// simple filters it can be done at offset that is a multiple of 2,
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// 4, or 16. With x86 filter, it needs good luck, and thus cannot
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// be made to work predictably.
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if (action == LZMA_SYNC_FLUSH)
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return LZMA_OPTIONS_ERROR;
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// Flush already filtered data from coder->buffer[] to out[].
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if (coder->pos < coder->filtered) {
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lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered,
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out, out_pos, out_size);
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// If we couldn't flush all the filtered data, return to
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// application immediately.
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if (coder->pos < coder->filtered)
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return LZMA_OK;
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if (coder->end_was_reached) {
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assert(coder->filtered == coder->size);
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return LZMA_STREAM_END;
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}
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}
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// If we get here, there is no filtered data left in the buffer.
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coder->filtered = 0;
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assert(!coder->end_was_reached);
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// If there is more output space left than there is unfiltered data
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// in coder->buffer[], flush coder->buffer[] to out[], and copy/code
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// more data to out[] hopefully filling it completely. Then filter
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// the data in out[]. This step is where most of the data gets
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// filtered if the buffer sizes used by the application are reasonable.
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out_avail = out_size - *out_pos;
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buf_avail = coder->size - coder->pos;
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if (out_avail > buf_avail || buf_avail == 0) {
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size_t size;
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size_t filtered;
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size_t unfiltered;
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// Store the old position so that we know from which byte
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// to start filtering.
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const size_t out_start = *out_pos;
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// Flush data from coder->buffer[] to out[], but don't reset
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// coder->pos and coder->size yet. This way the coder can be
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// restarted if the next filter in the chain returns e.g.
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// LZMA_MEM_ERROR.
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memcpy(out + *out_pos, coder->buffer + coder->pos, buf_avail);
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*out_pos += buf_avail;
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// Copy/Encode/Decode more data to out[].
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{
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const lzma_ret ret = copy_or_code(coder, allocator,
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in, in_pos, in_size,
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out, out_pos, out_size, action);
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assert(ret != LZMA_STREAM_END);
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if (ret != LZMA_OK)
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return ret;
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}
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// Filter out[].
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size = *out_pos - out_start;
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filtered = call_filter(coder, out + out_start, size);
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unfiltered = size - filtered;
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assert(unfiltered <= coder->allocated / 2);
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// Now we can update coder->pos and coder->size, because
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// the next coder in the chain (if any) was successful.
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coder->pos = 0;
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coder->size = unfiltered;
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if (coder->end_was_reached) {
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// The last byte has been copied to out[] already.
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// They are left as is.
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coder->size = 0;
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} else if (unfiltered > 0) {
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// There is unfiltered data left in out[]. Copy it to
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// coder->buffer[] and rewind *out_pos appropriately.
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*out_pos -= unfiltered;
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memcpy(coder->buffer, out + *out_pos, unfiltered);
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}
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} else if (coder->pos > 0) {
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memmove(coder->buffer, coder->buffer + coder->pos, buf_avail);
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coder->size -= coder->pos;
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coder->pos = 0;
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}
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assert(coder->pos == 0);
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// If coder->buffer[] isn't empty, try to fill it by copying/decoding
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// more data. Then filter coder->buffer[] and copy the successfully
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// filtered data to out[]. It is probable, that some filtered and
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// unfiltered data will be left to coder->buffer[].
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if (coder->size > 0) {
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{
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const lzma_ret ret = copy_or_code(coder, allocator,
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in, in_pos, in_size,
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coder->buffer, &coder->size,
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coder->allocated, action);
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assert(ret != LZMA_STREAM_END);
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if (ret != LZMA_OK)
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return ret;
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}
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coder->filtered = call_filter(
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coder, coder->buffer, coder->size);
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// Everything is considered to be filtered if coder->buffer[]
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// contains the last bytes of the data.
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if (coder->end_was_reached)
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coder->filtered = coder->size;
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// Flush as much as possible.
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lzma_bufcpy(coder->buffer, &coder->pos, coder->filtered,
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out, out_pos, out_size);
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}
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// Check if we got everything done.
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if (coder->end_was_reached && coder->pos == coder->size)
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return LZMA_STREAM_END;
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return LZMA_OK;
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}
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static void
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simple_coder_end(lzma_coder *coder, lzma_allocator *allocator)
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{
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lzma_next_end(&coder->next, allocator);
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lzma_free(coder->simple, allocator);
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lzma_free(coder, allocator);
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return;
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}
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static lzma_ret
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simple_coder_update(lzma_coder *coder, lzma_allocator *allocator,
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const lzma_filter *filters_null lzma_attribute((__unused__)),
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const lzma_filter *reversed_filters)
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{
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// No update support, just call the next filter in the chain.
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return lzma_next_filter_update(
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&coder->next, allocator, reversed_filters + 1);
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}
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extern lzma_ret
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lzma_simple_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
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const lzma_filter_info *filters,
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size_t (*filter)(lzma_simple *simple, uint32_t now_pos,
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bool is_encoder, uint8_t *buffer, size_t size),
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size_t simple_size, size_t unfiltered_max,
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uint32_t alignment, bool is_encoder)
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{
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// Allocate memory for the lzma_coder structure if needed.
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if (next->coder == NULL) {
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// Here we allocate space also for the temporary buffer. We
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// need twice the size of unfiltered_max, because then it
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// is always possible to filter at least unfiltered_max bytes
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// more data in coder->buffer[] if it can be filled completely.
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next->coder = lzma_alloc(sizeof(lzma_coder)
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+ 2 * unfiltered_max, allocator);
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if (next->coder == NULL)
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return LZMA_MEM_ERROR;
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next->code = &simple_code;
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next->end = &simple_coder_end;
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next->update = &simple_coder_update;
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next->coder->next = LZMA_NEXT_CODER_INIT;
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next->coder->filter = filter;
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next->coder->allocated = 2 * unfiltered_max;
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// Allocate memory for filter-specific data structure.
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if (simple_size > 0) {
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next->coder->simple = lzma_alloc(
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simple_size, allocator);
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if (next->coder->simple == NULL)
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return LZMA_MEM_ERROR;
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} else {
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next->coder->simple = NULL;
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}
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}
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if (filters[0].options != NULL) {
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const lzma_options_bcj *simple = filters[0].options;
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next->coder->now_pos = simple->start_offset;
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if (next->coder->now_pos & (alignment - 1))
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return LZMA_OPTIONS_ERROR;
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} else {
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next->coder->now_pos = 0;
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}
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// Reset variables.
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next->coder->is_encoder = is_encoder;
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next->coder->end_was_reached = false;
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next->coder->pos = 0;
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next->coder->filtered = 0;
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next->coder->size = 0;
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return lzma_next_filter_init(
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&next->coder->next, allocator, filters + 1);
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}
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