/*

 * Copyright (C) 2008 Jaikrishnan Menon

 * Copyright (C) 2011 Stefano Sabatini

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg 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.

 *

 * FFmpeg 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.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * 8svx audio decoder

 * @author Jaikrishnan Menon

 *

 * supports: fibonacci delta encoding

 *         : exponential encoding

 *

 * For more information about the 8SVX format:

 * http://netghost.narod.ru/gff/vendspec/iff/iff.txt

 * http://sox.sourceforge.net/AudioFormats-11.html

 * http://aminet.net/package/mus/misc/wavepak

 * http://amigan.1emu.net/reg/8SVX.txt

 *

 * Samples can be found here:

 * http://aminet.net/mods/smpl/

 */

#include "config_components.h"

#include "libavutil/avassert.h"

#include "libavutil/mem.h"

#include "avcodec.h"

#include "codec_internal.h"

#include "decode.h"

#include "libavutil/common.h"

/** decoder context */

typedef struct EightSvxContext {

    uint8_t fib_acc[2];

    const int8_t *table;

    /* buffer used to store the whole first packet.

       data is only sent as one large packet */

    uint8_t *data[2];

    int data_size;

    int data_idx;

} EightSvxContext;

static const int8_t fibonacci[16]   = { -34,  -21, -13,  -8, -5, -3, -2, -1, 0, 1, 2, 3, 5, 8,  13, 21 };

static const int8_t exponential[16] = { -128, -64, -32, -16, -8, -4, -2, -1, 0, 1, 2, 4, 8, 16, 32, 64 };

#define MAX_FRAME_SIZE 2048

/**

 * Delta decode the compressed values in src, and put the resulting

 * decoded samples in dst.

 *

 * @param[in,out] state starting value. it is saved for use in the next call.

 * @param table delta sequence table

 */

static void delta_decode(uint8_t *dst, const uint8_t *src, int src_size,

                         uint8_t *state, const int8_t *table)

{

    uint8_t val = *state;

    while (src_size--) {

        uint8_t d = *src++;

        val = av_clip_uint8(val + table[d & 0xF]);

        *dst++ = val;

        val = av_clip_uint8(val + table[d >> 4]);

        *dst++ = val;

    }

    *state = val;

}

/** decode a frame */

static int eightsvx_decode_frame(AVCodecContext *avctx, AVFrame *frame,

                                 int *got_frame_ptr, AVPacket *avpkt)

{

    EightSvxContext *esc = avctx->priv_data;

    int channels         = avctx->ch_layout.nb_channels;

    int buf_size;

    int ch, ret;

    int hdr_size = 2;

    /* decode and interleave the first packet */

    if (!esc->data[0] && avpkt) {

        int chan_size = avpkt->size / channels - hdr_size;

        if (avpkt->size % channels) {

            av_log(avctx, AV_LOG_WARNING, "Packet with odd size, ignoring last byte\n");

        }

        if (avpkt->size < (hdr_size + 1) * channels) {

            av_log(avctx, AV_LOG_ERROR, "packet size is too small\n");

            return AVERROR_INVALIDDATA;

        }

        esc->fib_acc[0] = avpkt->data[1] + 128;

        if (channels == 2)

            esc->fib_acc[1] = avpkt->data[2+chan_size+1] + 128;

        esc->data_idx  = 0;

        esc->data_size = chan_size;

        if (!(esc->data[0] = av_malloc(chan_size)))

            return AVERROR(ENOMEM);

        if (channels == 2) {

            if (!(esc->data[1] = av_malloc(chan_size))) {

                av_freep(&esc->data[0]);

                return AVERROR(ENOMEM);

            }

        }

        memcpy(esc->data[0], &avpkt->data[hdr_size], chan_size);

        if (channels == 2)

            memcpy(esc->data[1], &avpkt->data[2*hdr_size+chan_size], chan_size);

    }

    if (!esc->data[0]) {

        av_log(avctx, AV_LOG_ERROR, "unexpected empty packet\n");

        return AVERROR_INVALIDDATA;

    }

    /* decode next piece of data from the buffer */

    buf_size = FFMIN(MAX_FRAME_SIZE, esc->data_size - esc->data_idx);

    if (buf_size <= 0) {

        *got_frame_ptr = 0;

        return avpkt->size;

    }

    /* get output buffer */

    frame->nb_samples = buf_size * 2;

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

        return ret;

    for (ch = 0; ch < channels; ch++) {

        delta_decode(frame->data[ch], &esc->data[ch][esc->data_idx],

                     buf_size, &esc->fib_acc[ch], esc->table);

    }

    esc->data_idx += buf_size;

    *got_frame_ptr = 1;

    return ((avctx->frame_num == 0) * hdr_size + buf_size) * channels;

}

static av_cold int eightsvx_decode_init(AVCodecContext *avctx)

{

    EightSvxContext *esc = avctx->priv_data;

    if (avctx->ch_layout.nb_channels < 1 || avctx->ch_layout.nb_channels > 2) {

        av_log(avctx, AV_LOG_ERROR, "8SVX does not support more than 2 channels\n");

        return AVERROR_INVALIDDATA;

    }

    switch (avctx->codec->id) {

    case AV_CODEC_ID_8SVX_FIB: esc->table = fibonacci;    break;

    case AV_CODEC_ID_8SVX_EXP: esc->table = exponential;  break;

    default:

        av_assert1(0);

    }

    avctx->sample_fmt = AV_SAMPLE_FMT_U8P;

    return 0;

}

static av_cold int eightsvx_decode_close(AVCodecContext *avctx)

{

    EightSvxContext *esc = avctx->priv_data;

    av_freep(&esc->data[0]);

    av_freep(&esc->data[1]);

    esc->data_size = 0;

    esc->data_idx = 0;

    return 0;

}

#if CONFIG_EIGHTSVX_FIB_DECODER

const FFCodec ff_eightsvx_fib_decoder = {

  .p.name         = "8svx_fib",

  CODEC_LONG_NAME("8SVX fibonacci"),

  .p.type         = AVMEDIA_TYPE_AUDIO,

  .p.id           = AV_CODEC_ID_8SVX_FIB,

  .priv_data_size = sizeof (EightSvxContext),

  .init           = eightsvx_decode_init,

  FF_CODEC_DECODE_CB(eightsvx_decode_frame),

  .close          = eightsvx_decode_close,

  .p.capabilities = AV_CODEC_CAP_DR1,

};

#endif

#if CONFIG_EIGHTSVX_EXP_DECODER

const FFCodec ff_eightsvx_exp_decoder = {

  .p.name         = "8svx_exp",

  CODEC_LONG_NAME("8SVX exponential"),

  .p.type         = AVMEDIA_TYPE_AUDIO,

  .p.id           = AV_CODEC_ID_8SVX_EXP,

  .priv_data_size = sizeof (EightSvxContext),

  .init           = eightsvx_decode_init,

  FF_CODEC_DECODE_CB(eightsvx_decode_frame),

  .close          = eightsvx_decode_close,

  .p.capabilities = AV_CODEC_CAP_DR1,

};

#endif