The R Project SVN R

///////////////////////////////////////////////////////////////////////////////
//
/// \file       subblock_decoder_helper.c
/// \brief      Helper filter for the Subblock decoder
///
/// This filter is used to indicate End of Input for subfilters needing it.
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////

#include "subblock_decoder_helper.h"


struct lzma_coder_s {
    const lzma_options_subblock_helper *options;
};


static lzma_ret
helper_decode(lzma_coder *coder,
        lzma_allocator *allocator lzma_attribute((unused)),
        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_attribute((unused)))
{
    // If end_was_reached is true, we cannot have any input.
    assert(!coder->options->end_was_reached || *in_pos == in_size);

    // We can safely copy as much as possible, because we are never
    // given more data than a single Subblock Data field.
    lzma_bufcpy(in, in_pos, in_size, out, out_pos, out_size);

    // Return LZMA_STREAM_END when instructed so by the Subblock decoder.
    return coder->options->end_was_reached ? LZMA_STREAM_END : LZMA_OK;
}


static void
helper_end(lzma_coder *coder, lzma_allocator *allocator)
{
    lzma_free(coder, allocator);
    return;
}


extern lzma_ret
lzma_subblock_decoder_helper_init(lzma_next_coder *next,
        lzma_allocator *allocator, const lzma_filter_info *filters)
{
    // This is always the last filter in the chain.
    assert(filters[1].init == NULL);

    if (next->coder == NULL) {
        next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
        if (next->coder == NULL)
            return LZMA_MEM_ERROR;

        next->code = &helper_decode;
        next->end = &helper_end;
    }

    next->coder->options = filters[0].options;

    return LZMA_OK;
}