/*****************************************************************************

 * flac.h: fLAC audio headers

 *****************************************************************************

 * Copyright (C) 2001-2018 VLC authors, VideoLabs and VideoLAN

 *

 * This program 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.

 *

 * This program 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 this program; if not, write to the Free Software Foundation,

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

 *****************************************************************************/

#include <vlc_common.h>

#define FLAC_HEADER_SIZE_MIN 9

#define FLAC_HEADER_SIZE_MAX 16

#define FLAC_STREAMINFO_SIZE 34

#define FLAC_FRAME_SIZE_MIN ((48+(8 + 4 + 1*4)+FLAC_HEADER_SIZE_MAX)/8)

struct flac_stream_info

{

    unsigned min_blocksize, max_blocksize;

    unsigned min_framesize, max_framesize;

    unsigned sample_rate;

    unsigned channels;

    unsigned bits_per_sample;

    uint64_t total_samples;

};

struct flac_header_info

{

    vlc_tick_t i_pts;

    unsigned i_rate;

    unsigned i_channels;

    unsigned i_bits_per_sample;

    unsigned i_frame_length;

};

static inline void FLAC_ParseStreamInfo( const uint8_t *p_buf,

                                         struct flac_stream_info *stream_info )

{

    stream_info->min_blocksize = GetWBE( &p_buf[0] );

    stream_info->min_blocksize = VLC_CLIP( stream_info->min_blocksize, 16, 65535 );

    stream_info->max_blocksize = GetWBE( &p_buf[2] );

    stream_info->max_blocksize = VLC_CLIP( stream_info->max_blocksize, 16, 65535 );

    stream_info->min_framesize = GetDWBE( &p_buf[3] ) & 0x00FFFFFF;

    stream_info->min_framesize = __MAX( stream_info->min_framesize, FLAC_FRAME_SIZE_MIN );

    stream_info->max_framesize = GetDWBE( &p_buf[6] ) & 0x00FFFFFF;

    stream_info->sample_rate = GetDWBE( &p_buf[10] ) >> 12;

    stream_info->channels = ((p_buf[12] >> 1) & 0x07) + 1;

    stream_info->bits_per_sample = (((p_buf[12] & 0x01) << 4) | p_buf[13] >> 4) + 1;

    stream_info->total_samples = GetQWBE(&p_buf[4+6]) & ((INT64_C(1)<<36)-1);

}

/* Will return UINT64_MAX for an invalid utf-8 sequence */

static inline uint64_t read_utf8(const uint8_t *p_buf, unsigned i_buf, int *pi_read)

{

    /* Max coding bits is 56 - 8 */

    /* Value max precision is 36 bits */

    uint64_t i_result = 0;

    unsigned i;

    if(i_buf < 1)

        return UINT64_MAX;

    if (!(p_buf[0] & 0x80)) { /* 0xxxxxxx */

        i_result = p_buf[0];

        i = 0;

    } else if (p_buf[0] & 0xC0 && !(p_buf[0] & 0x20)) { /* 110xxxxx */

        i_result = p_buf[0] & 0x1F;

        i = 1;

    } else if (p_buf[0] & 0xE0 && !(p_buf[0] & 0x10)) { /* 1110xxxx */

        i_result = p_buf[0] & 0x0F;

        i = 2;

    } else if (p_buf[0] & 0xF0 && !(p_buf[0] & 0x08)) { /* 11110xxx */

        i_result = p_buf[0] & 0x07;

        i = 3;

    } else if (p_buf[0] & 0xF8 && !(p_buf[0] & 0x04)) { /* 111110xx */

        i_result = p_buf[0] & 0x03;

        i = 4;

    } else if (p_buf[0] & 0xFC && !(p_buf[0] & 0x02)) { /* 1111110x */

        i_result = p_buf[0] & 0x01;

        i = 5;

    } else if (p_buf[0] & 0xFE && !(p_buf[0] & 0x01)) { /* 11111110 */

        i_result = 0;

        i = 6;

    } else {

        return UINT64_MAX;

    }

    if(i_buf < i + 1)

        return UINT64_MAX;

    for (unsigned j = 1; j <= i; j++) {

        if (!(p_buf[j] & 0x80) || (p_buf[j] & 0x40)) { /* 10xxxxxx */

            return UINT64_MAX;

        }

        i_result <<= 6;

        i_result |= (p_buf[j] & 0x3F);

    }

    *pi_read = i;

    return i_result;

}

static inline int FLAC_CheckFrameInfo(const struct flac_stream_info *stream_info,

                                      const struct flac_header_info *h)

{

    /* Sanity check using stream info header when possible */

    if (stream_info)

    {

        if ((stream_info->min_blocksize != stream_info->max_blocksize &&

             h->i_frame_length < stream_info->min_blocksize) ||

            h->i_frame_length > stream_info->max_blocksize)

            return 0;

        if(stream_info->max_framesize &&

           stream_info->min_framesize > stream_info->max_framesize)

            return 0;

        if (h->i_bits_per_sample != stream_info->bits_per_sample)

            return 0;

        if (h->i_rate != stream_info->sample_rate)

            return 0;

    }

    return 1;

}

/*****************************************************************************

 * FLAC_ParseSyncInfo: parse FLAC sync info

 * - stream_info can be NULL

 * - pf_crc8 can be NULL to skip crc check

 * Returns: 1 on success, 0 on failure, and -1 if could be incorrect

 *****************************************************************************/

static inline int FLAC_ParseSyncInfo(const uint8_t *p_buf, unsigned i_buf,

                                     const struct flac_stream_info *stream_info,

                                     uint8_t(*pf_crc8)(const uint8_t *, size_t),

                                     struct flac_header_info *h)

{

    bool b_guessing = false;

    if(unlikely(i_buf < FLAC_HEADER_SIZE_MIN))

        return 0;

    /* Check syncword */

    if (p_buf[0] != 0xFF || (p_buf[1] & 0xFE) != 0xF8)

        return 0;

    /* Check there is no emulated sync code in the rest of the header */

    if (p_buf[2] == 0xff || p_buf[3] == 0xFF)

        return 0;

    /* Find blocksize (framelength) */

    int blocksize_hint = 0;

    unsigned blocksize = p_buf[2] >> 4;

    if (blocksize >= 8) {

        blocksize = 256 << (blocksize - 8);

    } else if (blocksize == 0) { /* value 0 is reserved */

        b_guessing = true;

        if (stream_info &&

            stream_info->min_blocksize == stream_info->max_blocksize)

            blocksize = stream_info->min_blocksize;

        else

            return 0; /* We can't do anything with this */

    } else if (blocksize == 1) {

        blocksize = 192;

    } else if (blocksize == 6 || blocksize == 7) {

        blocksize_hint = blocksize;

        blocksize = 0;

    } else /* 2, 3, 4, 5 */ {

        blocksize = 576 << (blocksize - 2);

    }

    if (stream_info && !blocksize_hint)

        if (blocksize < stream_info->min_blocksize ||

            blocksize > stream_info->max_blocksize)

            return 0;

    /* Find samplerate */

    int samplerate_hint = p_buf[2] & 0xf;

    unsigned int samplerate;

    if (samplerate_hint == 0) {

        if (stream_info)

            samplerate = stream_info->sample_rate;

        else

            return 0; /* We can't do anything with this */

    } else if (samplerate_hint == 15) {

        return 0; /* invalid */

    } else if (samplerate_hint < 12) {

        static const int16_t flac_samplerate[12] = {

            0,    8820, 17640, 19200,

            800,  1600, 2205,  2400,

            3200, 4410, 4800,  9600,

        };

        samplerate = flac_samplerate[samplerate_hint] * 10;

    } else {

        samplerate = 0; /* at end of header */

    }

    /* Find channels */

    unsigned channels = p_buf[3] >> 4;

    if (channels >= 8) {

        if (channels >= 11) /* reserved */

            return 0;

        channels = 2;

    } else

        channels++;

    /* Find bits per sample */

    static const int8_t flac_bits_per_sample[8] = {

        0, 8, 12, -1, 16, 20, 24, 32

    };

    int bits_per_sample = flac_bits_per_sample[(p_buf[3] & 0x0e) >> 1];

    if (bits_per_sample == 0) {

        if (stream_info)

            bits_per_sample = stream_info->bits_per_sample;

        else

            return 0;

    } else if (bits_per_sample < 0)

        return 0;

    /* reserved for future use */

    if (p_buf[3] & 0x01)

        return 0;

    /* End of fixed size header */

    unsigned i_header = 4;

    /* > FLAC_HEADER_SIZE_MIN checks start here */

    /* Check Sample/Frame number */

    int i_read;

    uint64_t i_fsnumber = read_utf8(&p_buf[i_header++], i_buf - 4, &i_read);

    /* Invalid UTF-8 */

    if (i_fsnumber == UINT64_MAX)

        return 0;

    /* Invalid Sample/Frame number */

    if (stream_info && stream_info->total_samples != 0 && i_fsnumber > stream_info->total_samples)

        return 0;

    i_header += i_read;

    /* Read blocksize */

    if (blocksize_hint) {

        if(i_header == i_buf)

            return 0;

        blocksize = p_buf[i_header++];

        if (blocksize_hint == 7) {

            blocksize <<= 8;

            blocksize |= p_buf[i_header++];

        }

        blocksize++;

    }

    /* Read sample rate */

    if (samplerate == 0) {

        if(i_header == i_buf)

            return 0;

        samplerate = p_buf[i_header++];

        if (samplerate_hint != 12) { /* 16 bits */

            if(i_header == i_buf)

                return 0;

            samplerate <<= 8;

            samplerate |= p_buf[i_header++];

        }

        if (samplerate_hint == 12)

            samplerate *= 1000;

        else if (samplerate_hint == 14)

            samplerate *= 10;

    }

    if ( !samplerate )

        return 0;

    if(i_header == i_buf) /* no crc space */

        return 0;

    /* Check the CRC-8 byte */

    if (pf_crc8 &&

        pf_crc8(p_buf, i_header) != p_buf[i_header])

        return 0;

    /* Compute from frame absolute time */

    if ( (p_buf[1] & 0x01) == 0  ) /* Fixed blocksize stream / Frames */

    {

        const unsigned fixedblocksize = stream_info ? stream_info->min_blocksize : blocksize;

        h->i_pts = VLC_TICK_0 + vlc_tick_from_samples(fixedblocksize * i_fsnumber, samplerate);

    }

    else /* Variable blocksize stream / Samples */

        h->i_pts = VLC_TICK_0 + vlc_tick_from_samples(i_fsnumber, samplerate);

    h->i_bits_per_sample = bits_per_sample;

    h->i_rate = samplerate;

    h->i_channels = channels;

    h->i_frame_length = blocksize;

    return b_guessing ? -1 : 1;

}