source: vbox/trunk/src/libs/liblzma-5.4.1/common/alone_encoder.c

///////////////////////////////////////////////////////////////////////////////
//
/// \file       alone_encoder.c
/// \brief      Encoder for LZMA_Alone files
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////

#include "common.h"
#include "lzma_encoder.h"


#define ALONE_HEADER_SIZE (1 + 4 + 8)


typedef struct {
        lzma_next_coder next;

        enum {
                SEQ_HEADER,
                SEQ_CODE,
        } sequence;

        size_t header_pos;
        uint8_t header[ALONE_HEADER_SIZE];
} lzma_alone_coder;


static lzma_ret
alone_encode(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_alone_coder *coder = coder_ptr;

        while (*out_pos < out_size)
        switch (coder->sequence) {
        case SEQ_HEADER:
                lzma_bufcpy(coder->header, &coder->header_pos,
                                ALONE_HEADER_SIZE,
                                out, out_pos, out_size);
                if (coder->header_pos < ALONE_HEADER_SIZE)
                        return LZMA_OK;

                coder->sequence = SEQ_CODE;
                break;

        case SEQ_CODE:
                return coder->next.code(coder->next.coder,
                                allocator, in, in_pos, in_size,
                                out, out_pos, out_size, action);

        default:
                assert(0);
                return LZMA_PROG_ERROR;
        }

        return LZMA_OK;
}


static void
alone_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
{
        lzma_alone_coder *coder = coder_ptr;
        lzma_next_end(&coder->next, allocator);
        lzma_free(coder, allocator);
        return;
}


// At least for now, this is not used by any internal function.
static lzma_ret
alone_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
                const lzma_options_lzma *options)
{
        lzma_next_coder_init(&alone_encoder_init, next, allocator);

        lzma_alone_coder *coder = next->coder;

        if (coder == NULL) {
                coder = lzma_alloc(sizeof(lzma_alone_coder), allocator);
                if (coder == NULL)
                        return LZMA_MEM_ERROR;

                next->coder = coder;
                next->code = &alone_encode;
                next->end = &alone_encoder_end;
                coder->next = LZMA_NEXT_CODER_INIT;
        }

        // Basic initializations
        coder->sequence = SEQ_HEADER;
        coder->header_pos = 0;

        // Encode the header:
        // - Properties (1 byte)
        if (lzma_lzma_lclppb_encode(options, coder->header))
                return LZMA_OPTIONS_ERROR;

        // - Dictionary size (4 bytes)
        if (options->dict_size < LZMA_DICT_SIZE_MIN)
                return LZMA_OPTIONS_ERROR;

        // Round up to the next 2^n or 2^n + 2^(n - 1) depending on which
        // one is the next unless it is UINT32_MAX. While the header would
        // allow any 32-bit integer, we do this to keep the decoder of liblzma
        // accepting the resulting files.
        uint32_t d = options->dict_size - 1;
        d |= d >> 2;
        d |= d >> 3;
        d |= d >> 4;
        d |= d >> 8;
        d |= d >> 16;
        if (d != UINT32_MAX)
                ++d;

        write32le(coder->header + 1, d);

        // - Uncompressed size (always unknown and using EOPM)
        memset(coder->header + 1 + 4, 0xFF, 8);

        // Initialize the LZMA encoder.
        const lzma_filter_info filters[2] = {
                {
                        .id = LZMA_FILTER_LZMA1,
                        .init = &lzma_lzma_encoder_init,
                        .options = (void *)(options),
                }, {
                        .init = NULL,
                }
        };

        return lzma_next_filter_init(&coder->next, allocator, filters);
}


/*
extern lzma_ret
lzma_alone_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
                const lzma_options_alone *options)
{
        lzma_next_coder_init(&alone_encoder_init, next, allocator, options);
}
*/


extern LZMA_API(lzma_ret)
lzma_alone_encoder(lzma_stream *strm, const lzma_options_lzma *options)
{
        lzma_next_strm_init(alone_encoder_init, strm, options);

        strm->internal->supported_actions[LZMA_RUN] = true;
        strm->internal->supported_actions[LZMA_FINISH] = true;

        return LZMA_OK;
}