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