/*
    DeaDBeeF - ultimate music player for GNU/Linux systems with X11
    Copyright (C) 2009-2011 Alexey Yakovenko <waker@users.sourceforge.net>

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    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 General Public License for more details.
    
    You should have received a copy of the GNU 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.
*/

// based on xmms-shn, http://www.etree.org/shnutils/xmms-shn/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "shorten.h"
#include "../../deadbeef.h"
#include "bitshift.h"

//#define trace(...) { fprintf(stderr, __VA_ARGS__); }
#define trace(fmt,...)

static DB_decoder_t plugin;
DB_functions_t *deadbeef;

shn_file *load_shn(const char *filename);

typedef struct {
    DB_fileinfo_t info;
    shn_file *shnfile;

    slong  **buffer, **offset;
    slong  lpcqoffset;
    int   version, bitshift;
    int   ftype;
    char  *magic;
    int   blocksize, nchan;
    int   i, chan, nwrap, nskip;
    int   *qlpc, maxnlpc, nmean;
    int   cmd;
    int   internal_ftype;
    int   blk_size;
    int   cklen;
    uchar tmp;

    int currentsample;
    int startsample;
    int endsample;

    int skipsamples;
} shn_fileinfo_t;

shn_config shn_cfg;

DB_fileinfo_t *
shn_open (uint32_t hints) {
    DB_fileinfo_t *_info = malloc (sizeof (shn_fileinfo_t));
    shn_fileinfo_t *info = (shn_fileinfo_t *)_info;
    memset (info, 0, sizeof (shn_fileinfo_t));
    return _info;
}

int
ddb_getc (DB_FILE *fp) {
    uint8_t c;
    if (deadbeef->fread (&c, 1, 1, fp) != 1) {
        return EOF;
    }
    return (int)c;
}

int init_decode_state(shn_file *this_shn)
{
	if (this_shn->decode_state)
	{
		if (this_shn->decode_state->getbuf)
		{
			free(this_shn->decode_state->getbuf);
			this_shn->decode_state->getbuf = NULL;
		}

		if (this_shn->decode_state->writebuf)
		{
			free(this_shn->decode_state->writebuf);
			this_shn->decode_state->writebuf = NULL;
		}

		if (this_shn->decode_state->writefub)
		{
			free(this_shn->decode_state->writefub);
			this_shn->decode_state->writefub = NULL;
		}

		free(this_shn->decode_state);
		this_shn->decode_state = NULL;
	}

	if (!(this_shn->decode_state = malloc(sizeof(shn_decode_state))))
	{
		shn_debug("Could not allocate memory for decode state data structure");
		return 0;
	}

	this_shn->decode_state->getbuf = NULL;
	this_shn->decode_state->getbufp = NULL;
	this_shn->decode_state->nbitget = 0;
	this_shn->decode_state->nbyteget = 0;
	this_shn->decode_state->gbuffer = 0;
	this_shn->decode_state->writebuf = NULL;
    this_shn->decode_state->writefub = NULL;
    this_shn->decode_state->nwritebuf = 0;

    this_shn->vars.bytes_in_buf = 0;

    return 1;
}

int
shn_init_decoder (shn_fileinfo_t *info) {
    int version = FORMAT_VERSION;
    info->ftype = TYPE_EOF;
    info->magic = MAGIC;
    info->blocksize = DEFAULT_BLOCK_SIZE;
    info->nchan = DEFAULT_NCHAN;
    info->nskip = DEFAULT_NSKIP;
    info->maxnlpc = DEFAULT_MAXNLPC;
    info->nmean = UNDEFINED_UINT;

    info->shnfile->vars.bytes_in_buf = 0;
    if (!init_decode_state(info->shnfile)) {
        trace ("shn: init_decode_state failed\n");
        return -1;
    }
    info->shnfile->vars.going = 1;

    info->blk_size = 512 * (info->shnfile->wave_header.bits_per_sample / 8) * info->shnfile->wave_header.channels;

    /* read magic number */
#ifdef STRICT_FORMAT_COMPATABILITY
    if(FORMAT_VERSION < 2)
    {
        for(i = 0; i < strlen(magic); i++)
            if(getc_exit(this_shn->vars.fd) != magic[i]) {
                shn_error_fatal(this_shn,"Bad magic number");
                goto exit_thread;
            }

        /* get version number */
        version = getc_exit(this_shn->vars.fd);
    }
    else
#endif /* STRICT_FORMAT_COMPATABILITY */
    {
        int nscan = 0;

        version = MAX_VERSION + 1;
        while(version > MAX_VERSION)
        {
            int byte = ddb_getc(info->shnfile->vars.fd);
            if(byte == EOF) {
                shn_error_fatal(info->shnfile,"No magic number");
                trace ("shn_init: no magic number\n");
                return -1;
            }
            if(info->magic[nscan] != '\0' && byte == info->magic[nscan]) {
                nscan++;
            }
            else {
                if(info->magic[nscan] == '\0' && byte <= MAX_VERSION)
                    version = byte;
                else
                {
                    if(byte == info->magic[0])
                        nscan = 1;
                    else
                    {
                        nscan = 0;
                    }
                    version = MAX_VERSION + 1;
                }
            }
        }
    }

    /* check version number */
    if(version > MAX_SUPPORTED_VERSION) {
        shn_error_fatal(info->shnfile,"Can't decode version %d", version);
        trace ("shn_init: can't decode version %d\n", version);
        return -1;
    }

    /* set up the default nmean, ignoring the command line state */
    info->nmean = (version < 2) ? DEFAULT_V0NMEAN : DEFAULT_V2NMEAN;

    /* initialise the variable length file read for the compressed stream */
    trace ("decode_state=%p\n", info->shnfile->decode_state);
    var_get_init(info->shnfile);
    if (info->shnfile->vars.fatal_error) {
        trace ("var_get_init failed\n");
        return -1;
    }

    /* initialise the fixed length file write for the uncompressed stream */
    fwrite_type_init(info->shnfile);

    /* get the internal file type */
    info->internal_ftype = UINT_GET(TYPESIZE, info->shnfile);
    trace ("internal_ftype=%d\n", info->internal_ftype);

    /* has the user requested a change in file type? */
    if(info->internal_ftype != info->ftype) {
        if(info->ftype == TYPE_EOF) {
            info->ftype = info->internal_ftype;    /*  no problems here */
        }
        else {            /* check that the requested conversion is valid */
            if(info->internal_ftype == TYPE_AU1 || info->internal_ftype == TYPE_AU2 ||
                    info->internal_ftype == TYPE_AU3 || info->ftype == TYPE_AU1 || info->ftype == TYPE_AU2 || info->ftype == TYPE_AU3) {
                shn_error_fatal(info->shnfile,"Not able to perform requested output format conversion");
                trace ("shn_init_decoder: Not able to perform requested output format conversion\n");
                return -1;
            }
        }
        trace ("ftype=%d\n", info->ftype);
    }

    info->nchan = UINT_GET(CHANSIZE, info->shnfile);

    /* get blocksize if version > 0 */
    if(version > 0)
    {
        int byte;
        info->blocksize = UINT_GET((int) (log((double) DEFAULT_BLOCK_SIZE) / M_LN2),info->shnfile);
        info->maxnlpc = UINT_GET(LPCQSIZE, info->shnfile);
        info->nmean = UINT_GET(0, info->shnfile);
        info->nskip = UINT_GET(NSKIPSIZE, info->shnfile);
        for(int i = 0; i < info->nskip; i++)
        {
            byte = uvar_get(XBYTESIZE,info->shnfile);
        }
    }
    else
        info->blocksize = DEFAULT_BLOCK_SIZE;

    info->nwrap = MAX(NWRAP, info->maxnlpc);

    /* grab some space for the input buffer */
    info->buffer  = long2d((ulong) info->nchan, (ulong) (info->blocksize + info->nwrap),info->shnfile);
    if (info->shnfile->vars.fatal_error) {
        trace ("failed to alloc buffer\n");
        return -1;
    }
    info->offset  = long2d((ulong) info->nchan, (ulong) MAX(1, info->nmean),info->shnfile);
    if (info->shnfile->vars.fatal_error) {
        if (info->buffer) {
            free(info->buffer);
            info->buffer = NULL;
        }
        trace ("failed to alloc offset\n");
        return -1;
    }

    for(info->chan = 0; info->chan < info->nchan; info->chan++)
    {
        for(int i = 0; i < info->nwrap; i++)
            info->buffer[info->chan][i] = 0;
        info->buffer[info->chan] += info->nwrap;
    }

    if(info->maxnlpc > 0) {
        info->qlpc = (int*) pmalloc((ulong) (info->maxnlpc * sizeof(*info->qlpc)),info->shnfile);
        if (info->shnfile->vars.fatal_error) {
            if (info->buffer) {
                free(info->buffer);
                info->buffer = NULL;
            }
            if (info->offset) {
                free(info->offset);
                info->offset = NULL;
            }
            trace ("failed to alloc qlpc\n");
            return -1;
        }
    }

    if(version > 1)
        info->lpcqoffset = V2LPCQOFFSET;

    init_offset (info->offset, info->nchan, MAX(1, info->nmean), info->internal_ftype);

    /* get commands from file and execute them */
    info->chan = 0;
    info->version = version;
    trace ("shn_init: success\n");
    return 0;
}

static void
shn_init_config (void) {
	shn_cfg.error_output_method = ERROR_OUTPUT_DEVNULL;

	deadbeef->conf_get_str ("shn.seektable_path", "", shn_cfg.seek_tables_path, sizeof (shn_cfg.seek_tables_path));
	deadbeef->conf_get_str ("shn.relative_seektable_path", "seektables", shn_cfg.relative_seek_tables_path, sizeof (shn_cfg.relative_seek_tables_path));
	shn_cfg.verbose = 0;
	shn_cfg.swap_bytes = deadbeef->conf_get_int ("shn.swap_bytes", 0);
}

int
shn_init(DB_fileinfo_t *_info, DB_playItem_t *it) {
    trace ("shn_init\n");
    shn_fileinfo_t *info = (shn_fileinfo_t *)_info;
    shn_init_config ();

	char data[4];
    DB_FILE *f;

	f = deadbeef->fopen (deadbeef->pl_find_meta (it, ":URI"));
    if (!f) {
        trace ("shn: failed to open %s\n", deadbeef->pl_find_meta (it, ":URI"));
        return -1;
    }

    int id3v2_tag_size = deadbeef->junk_get_leading_size (f);
    if (id3v2_tag_size > 0) {
        deadbeef->fseek (f, id3v2_tag_size, SEEK_SET);
    }

	if (deadbeef->fread((void *)data,1,4,f) != 4)
	{
		deadbeef->fclose(f);
        trace ("shn: failed to read magic from %s\n", deadbeef->pl_find_meta (it, ":URI"));
		return -1;
	}
	deadbeef->fclose(f);

	if (memcmp(data,MAGIC,4)) {
        trace ("shn: invalid MAGIC\n");
		return -1;
    }

	if (!(info->shnfile = load_shn(deadbeef->pl_find_meta (it, ":URI")))) {
        trace ("shn: load_shn failed\n");
		return -1;
    }

    _info->fmt.bps = info->shnfile->wave_header.bits_per_sample;
    _info->fmt.channels = info->shnfile->wave_header.channels;
    _info->fmt.samplerate  = info->shnfile->wave_header.samples_per_sec;
    for (int i = 0; i < _info->fmt.channels; i++) {
        _info->fmt.channelmask |= 1 << i;
    }
    _info->plugin = &plugin;

    int totalsamples = info->shnfile->wave_header.length * info->shnfile->wave_header.samples_per_sec;
    trace ("totalsamples: %d\n", totalsamples);

    if (it->endsample > 0) {
        info->startsample = it->startsample;
        info->endsample = it->endsample;
        plugin.seek_sample (_info, 0);
    }
    else {
        info->startsample = 0;
        info->endsample = totalsamples-1;
    }

    if (info->shnfile->wave_header.file_has_id3v2_tag) {
        deadbeef->fseek (info->shnfile->vars.fd, info->shnfile->wave_header.file_has_id3v2_tag, SEEK_SET);
    }
    else {
        deadbeef->rewind (info->shnfile->vars.fd);
    }

    if (shn_init_decoder (info) < 0) {
        trace ("shn_init_decoder failed\n");
        return -1;
    }

    return 0;
}

void
shn_free_decoder (shn_fileinfo_t *info) {
    if (info->shnfile) {
        if (info->shnfile->decode_state) {
            if(info->shnfile->decode_state->writebuf != NULL) {
                free(info->shnfile->decode_state->writebuf);
                info->shnfile->decode_state->writebuf = NULL;
            }
            if(info->shnfile->decode_state->writefub != NULL) {
                free(info->shnfile->decode_state->writefub);
                info->shnfile->decode_state->writefub = NULL;
            }
        }
    }
}

void
shn_free (DB_fileinfo_t *_info) {
    shn_fileinfo_t *info = (shn_fileinfo_t *)_info;
    shn_free_decoder (info);
    if (info->shnfile) {
        shn_unload(info->shnfile);
        info->shnfile = NULL;
    }
    if (info->buffer) {
        free(info->buffer);
        info->buffer = NULL;
    }
    if (info->offset) {
        free(info->offset);
        info->offset = NULL;
    }
    if(info->maxnlpc > 0 && info->qlpc) {
        free(info->qlpc);
        info->qlpc = NULL;
    }
    free (info);
}

void
swap_bytes(shn_file *this_shn,int bytes)
{
	int i;
	uchar tmp;

	for (i=0;i<bytes;i=i+2) {
		tmp = this_shn->vars.buffer[i+1];
		this_shn->vars.buffer[i+1] = this_shn->vars.buffer[i];
		this_shn->vars.buffer[i] = tmp;
	}
}

int
shn_decode (shn_fileinfo_t *info) {
    int i;
    int version = info->version;
    while(1)
    {
        info->cmd = uvar_get(FNSIZE,info->shnfile);
        if (info->shnfile->vars.fatal_error) {
            trace ("shn_decode: uvar_get error\n");
            return -1;
        }

        switch(info->cmd)
        {
        case FN_ZERO:
        case FN_DIFF0:
        case FN_DIFF1:
        case FN_DIFF2:
        case FN_DIFF3:
        case FN_QLPC:
            {
                slong coffset, *cbuffer = info->buffer[info->chan];
                int resn = 0, nlpc, j;

                if(info->cmd != FN_ZERO)
                {
                    resn = uvar_get(ENERGYSIZE,info->shnfile);
                    if (info->shnfile->vars.fatal_error) {
                        trace ("shn_decode: error 1\n");
                        return -1;
                    }
                    /* this is a hack as version 0 differed in definition of var_get */
                    if(info->version == 0)
                        resn--;
                }

                /* find mean offset : N.B. this code duplicated */
                if(info->nmean == 0)
                    coffset = info->offset[info->chan][0];
                else
                {
                    slong sum = (info->version < 2) ? 0 : info->nmean / 2;
                    for(i = 0; i < info->nmean; i++)
                        sum += info->offset[info->chan][i];
                    if(info->version < 2)
                        coffset = sum / info->nmean;
                    else
                        coffset = ROUNDEDSHIFTDOWN(sum / info->nmean, info->bitshift);
                }

                switch(info->cmd)
                {
                case FN_ZERO:
                    for(i = 0; i < info->blocksize; i++)
                        cbuffer[i] = 0;
                    break;
                case FN_DIFF0:
                    for(i = 0; i < info->blocksize; i++) {
                        cbuffer[i] = var_get(resn,info->shnfile) + coffset;
                        if (info->shnfile->vars.fatal_error) {
                            trace ("shn_decode: error 2\n");
                            return -1;
                        }
                    }
                    break;
                case FN_DIFF1:
                    for(i = 0; i < info->blocksize; i++) {
                        cbuffer[i] = var_get(resn,info->shnfile) + cbuffer[i - 1];
                        if (info->shnfile->vars.fatal_error) {
                            trace ("shn_decode: error 3\n");
                            return -1;
                        }
                    }
                    break;
                case FN_DIFF2:
                    for(i = 0; i < info->blocksize; i++) {
                        cbuffer[i] = var_get(resn,info->shnfile) + (2 * cbuffer[i - 1] -	cbuffer[i - 2]);
                        if (info->shnfile->vars.fatal_error) {
                            trace ("shn_decode: error 4\n");
                            return -1;
                        }
                    }
                    break;
                case FN_DIFF3:
                    for(i = 0; i < info->blocksize; i++) {
                        cbuffer[i] = var_get(resn,info->shnfile) + 3 * (cbuffer[i - 1] -  cbuffer[i - 2]) + cbuffer[i - 3];
                        if (info->shnfile->vars.fatal_error) {
                            trace ("shn_decode: error 5\n");
                            return -1;
                        }
                    }
                    break;
                case FN_QLPC:
                    nlpc = uvar_get(LPCQSIZE,info->shnfile);
                    if (info->shnfile->vars.fatal_error) {
                        trace ("shn_decode: error 6\n");
                        return -1;
                    }

                    for(i = 0; i < nlpc; i++) {
                        info->qlpc[i] = var_get(LPCQUANT,info->shnfile);
                        if (info->shnfile->vars.fatal_error) {
                            trace ("shn_decode: error 7\n");
                            return -1;
                        }
                    }
                    for(i = 0; i < nlpc; i++)
                        cbuffer[i - nlpc] -= coffset;
                    for(i = 0; i < info->blocksize; i++)
                    {
                        slong sum = info->lpcqoffset;

                        for(j = 0; j < nlpc; j++)
                            sum += info->qlpc[j] * cbuffer[i - j - 1];
                        cbuffer[i] = var_get(resn,info->shnfile) + (sum >> LPCQUANT);
                        if (info->shnfile->vars.fatal_error) {
                            trace ("shn_decode: error 8\n");
                            return -1;
                        }
                    }
                    if(coffset != 0)
                        for(i = 0; i < info->blocksize; i++)
                            cbuffer[i] += coffset;
                    break;
                }

                /* store mean value if appropriate : N.B. Duplicated code */
                if(info->nmean > 0)
                {
                    slong sum = (info->version < 2) ? 0 : info->blocksize / 2;

                    for(i = 0; i < info->blocksize; i++)
                        sum += cbuffer[i];

                    for(i = 1; i < info->nmean; i++)
                        info->offset[info->chan][i - 1] = info->offset[info->chan][i];
                    if(info->version < 2)
                        info->offset[info->chan][info->nmean - 1] = sum / info->blocksize;
                    else
                        info->offset[info->chan][info->nmean - 1] = (sum / info->blocksize) << info->bitshift;
                }

                /* do the wrap */
                for(i = -info->nwrap; i < 0; i++)
                    cbuffer[i] = cbuffer[i + info->blocksize];

                fix_bitshift(cbuffer, info->blocksize, info->bitshift, info->internal_ftype);

                if(info->chan == info->nchan - 1)
                {
                    if (!info->shnfile->vars.going || info->shnfile->vars.fatal_error) {
                        trace ("shn_decode: error 9\n");
                        return -1;
                    }

                    fwrite_type(info->buffer, info->ftype, info->nchan, info->blocksize, info->shnfile);
                    info->chan = (info->chan + 1) % info->nchan;
                    // now we have buffer of size info->shnfile->vars.bytes_in_buf
                    if (shn_cfg.swap_bytes) {
                        swap_bytes(info->shnfile, info->shnfile->vars.bytes_in_buf);
                    }
                    return info->shnfile->vars.bytes_in_buf;


// !!!!!!!!!!!!!!!!!!FIXME
 //                   write_and_wait(info->shnfile,blk_size);

#if 0 // seeking
                    if (info->shnfile->vars.seek_to != -1)
                    {
                        shn_seek_entry *seek_info;
                        int j;

                        shn_debug("Seeking to %d:%02d",info->shnfile->vars.seek_to/60,info->shnfile->vars.seek_to%60);

                        seek_info = shn_seek_entry_search(info->shnfile->seek_table,info->shnfile->vars.seek_to * (ulong)info->shnfile->wave_header.samples_per_sec,0,
                                (ulong)(info->shnfile->vars.seek_table_entries - 1),info->shnfile->vars.seek_resolution);

                        /* loop through number of channels in this file */
                        for (i=0;i<info->nchan;i++) {
                            /* load the three sample buffer values for this channel */
                            for (j=0;j<3;j++)
                                info->buffer[i][j-3] = shn_uchar_to_slong_le(seek_info->data+32+12*i-4*j);

                            /* load the variable number of offset history values for this channel */
                            for (j=0;j<MAX(1,info->nmean);j++)
                                info->offset[i][j]  = shn_uchar_to_slong_le(seek_info->data+48+16*i+4*j);
                        }

                        info->bitshift = shn_uchar_to_ushort_le(seek_info->data+22);

                        info->seekto_offset = shn_uchar_to_ulong_le(seek_info->data+8) + info->shnfile->vars.seek_offset;

                        deadbeef->fseek(info->shnfile->vars.fd,(slong)seekto_offset,SEEK_SET);
                        deadbeef->fread((uchar*) info->shnfile->decode_state->getbuf, 1, BUFSIZ, info->shnfile->vars.fd);

                        info->shnfile->decode_state->getbufp = info->shnfile->decode_state->getbuf + shn_uchar_to_ushort_le(seek_info->data+14);
                        info->shnfile->decode_state->nbitget = shn_uchar_to_ushort_le(seek_info->data+16);
                        info->shnfile->decode_state->nbyteget = shn_uchar_to_ushort_le(seek_info->data+12);
                        info->shnfile->decode_state->gbuffer = shn_uchar_to_ulong_le(seek_info->data+18);

                        info->shnfile->vars.bytes_in_buf = 0;

                        shn_ip.output->flush(info->shnfile->vars.seek_to * 1000);
                        info->shnfile->vars.seek_to = -1;
                    }
#endif

                }
                info->chan = (info->chan + 1) % info->nchan;
                break;
            }

            break;

        case FN_QUIT:
            /* empty out last of buffer */
            info->shnfile->vars.eof = 1;
            if (shn_cfg.swap_bytes) {
                swap_bytes(info->shnfile, info->shnfile->vars.bytes_in_buf);
            }
            return info->shnfile->vars.bytes_in_buf;
#if 0
            write_and_wait(info->shnfile,info->shnfile->vars.bytes_in_buf);
            info->shnfile->vars.eof = 1;

            while (1)
            {
                if (!info->shnfile->vars.going)
                    goto finish;
                if (info->shnfile->vars.seek_to != -1)
                {
                    var_get_quit(info->shnfile);
                    fwrite_type_quit(info->shnfile);

                    if (buffer) free((void *) buffer);
                    if (offset) free((void *) offset);
                    if(maxnlpc > 0 && qlpc)
                        free((void *) qlpc);

                    fseek(info->shnfile->vars.fd,0,SEEK_SET);
                    goto restart;
                }
                else
                    xmms_usleep(10000);
            }

            goto cleanup;
#endif
            break;

        case FN_BLOCKSIZE:
            info->blocksize = UINT_GET((int) (log((double) info->blocksize) / M_LN2), info->shnfile);
            if (info->shnfile->vars.fatal_error) {
                trace ("shn_decode: error 10\n");
                return -1;
            }
            break;
        case FN_BITSHIFT:
            info->bitshift = uvar_get(BITSHIFTSIZE,info->shnfile);
            if (info->shnfile->vars.fatal_error) {
                trace ("shn_decode: error 11\n");
                return -1;
            }
            break;
        case FN_VERBATIM:
            info->cklen = uvar_get(VERBATIM_CKSIZE_SIZE,info->shnfile);
            if (info->shnfile->vars.fatal_error) {
                trace ("shn_decode: error 12\n");
                return -1;
            }

            while (info->cklen--) {
                info->tmp = (uchar)uvar_get(VERBATIM_BYTE_SIZE,info->shnfile);
                if (info->shnfile->vars.fatal_error) {
                    trace ("shn_decode: error 13\n");
                    return -1;
                }
            }

            break;

        default:
            shn_error_fatal(info->shnfile,"Sanity check fails trying to decode function: %d",info->cmd);
            trace ("shn_decode: error 14\n");
            return -1;
        }
    }
    return 0;
}

int
shn_read (DB_fileinfo_t *_info, char *bytes, int size) {
    shn_fileinfo_t *info = (shn_fileinfo_t *)_info;
    int samplesize = _info->fmt.channels * _info->fmt.bps / 8;
    if (info->currentsample + size / samplesize > info->endsample) {
        size = (info->endsample - info->currentsample + 1) * samplesize;
        if (size <= 0) {
            return 0;
        }
    }
    int initsize = size;

    while (size > 0) {
        if (info->shnfile->vars.bytes_in_buf > 0) {
            int n = size / samplesize;
            int nsamples = info->shnfile->vars.bytes_in_buf / samplesize;
            if (info->skipsamples > 0) {
                int nskip = min(nsamples, info->skipsamples);
                info->skipsamples -= nskip;
                if (nskip == nsamples) {
                    info->shnfile->vars.bytes_in_buf = 0;
                    continue;
                }
                else {
                    memmove (info->shnfile->vars.buffer, info->shnfile->vars.buffer + nskip * samplesize, info->shnfile->vars.bytes_in_buf - nskip * samplesize);
                    nsamples -= nskip;
                    continue;
                }
            }
            n = min (nsamples, n);
            char *src = (char *)info->shnfile->vars.buffer;
            memcpy (bytes, src, samplesize * n);
            src += samplesize * n;
            bytes += samplesize * n;
            size -= n * samplesize;
            if (n == info->shnfile->vars.bytes_in_buf / samplesize) {
                info->shnfile->vars.bytes_in_buf = 0;
            }
            else {
                memmove (info->shnfile->vars.buffer, src, info->shnfile->vars.bytes_in_buf - n * samplesize);
                info->shnfile->vars.bytes_in_buf -= n * samplesize;
            }
            continue;
        }
        if (shn_decode (info) <= 0) {
            trace ("shn_decode returned error\n");
            break;
        }
    }

    info->currentsample += (initsize-size) / samplesize;
    if (size != 0) {
        trace ("shn_read_int16 eof\n");
    }
    return initsize-size;
}

int
shn_seek_sample (DB_fileinfo_t *_info, int sample) {
    shn_fileinfo_t *info = (shn_fileinfo_t *)_info;

    sample += info->startsample;

    info->shnfile->vars.seek_to = sample / _info->fmt.samplerate;

    if (info->shnfile->vars.seek_table_entries == NO_SEEK_TABLE) {
        // seek by skipping samples from the start
        if (sample > info->currentsample) {
            info->skipsamples = sample - info->currentsample;
        }
        else {
            // restart
            shn_free_decoder (info);
            deadbeef->rewind (info->shnfile->vars.fd);
            if (shn_init_decoder (info) < 0) {
                return -1;
            }
            info->skipsamples = sample;
        }
        info->currentsample = info->shnfile->vars.seek_to * _info->fmt.samplerate;
        _info->readpos = info->shnfile->vars.seek_to;
        return 0;
    }

    ulong seekto_offset;
    int i, j;
    shn_seek_entry *seek_info;

    trace ("Seeking to %d:%02d\n",info->shnfile->vars.seek_to/60,info->shnfile->vars.seek_to%60);

    seek_info = shn_seek_entry_search(info->shnfile->seek_table,info->shnfile->vars.seek_to * (ulong)info->shnfile->wave_header.samples_per_sec,0,
            (ulong)(info->shnfile->vars.seek_table_entries - 1),info->shnfile->vars.seek_resolution);

    /* loop through number of channels in this file */
    for (i=0;i<info->nchan;i++) {
        /* load the three sample buffer values for this channel */
        for (j=0;j<3;j++)
            info->buffer[i][j-3] = shn_uchar_to_slong_le(seek_info->data+32+12*i-4*j);

        /* load the variable number of offset history values for this channel */
        for (j=0;j<MAX(1,info->nmean);j++)
            info->offset[i][j]  = shn_uchar_to_slong_le(seek_info->data+48+16*i+4*j);
    }

    info->bitshift = shn_uchar_to_ushort_le(seek_info->data+22);

    seekto_offset = shn_uchar_to_ulong_le(seek_info->data+8) + info->shnfile->vars.seek_offset;

    deadbeef->fseek(info->shnfile->vars.fd,(slong)seekto_offset,SEEK_SET);
    deadbeef->fread((uchar*) info->shnfile->decode_state->getbuf, 1, BUFSIZ, info->shnfile->vars.fd);

    info->shnfile->decode_state->getbufp = info->shnfile->decode_state->getbuf + shn_uchar_to_ushort_le(seek_info->data+14);
    info->shnfile->decode_state->nbitget = shn_uchar_to_ushort_le(seek_info->data+16);
    info->shnfile->decode_state->nbyteget = shn_uchar_to_ushort_le(seek_info->data+12);
    info->shnfile->decode_state->gbuffer = shn_uchar_to_ulong_le(seek_info->data+18);

    info->shnfile->vars.bytes_in_buf = 0;

    info->currentsample = info->shnfile->vars.seek_to * _info->fmt.samplerate;
    _info->readpos = info->shnfile->vars.seek_to;
    return 0;
}

int
shn_seek (DB_fileinfo_t *_info, float time) {
    return shn_seek_sample (_info, time * _info->fmt.samplerate);
    return 0;
}

DB_playItem_t *
shn_insert (ddb_playlist_t *plt, DB_playItem_t *after, const char *fname) {
	shn_file *tmp_file;
	DB_FILE *f;
	char data[4];

	f = deadbeef->fopen (fname);
    if (!f) {
        return NULL;
    }
    int64_t fsize = deadbeef->fgetlength (f);

    int id3v2_tag_size = deadbeef->junk_get_leading_size (f);
    if (id3v2_tag_size > 0) {
        deadbeef->fseek (f, id3v2_tag_size, SEEK_SET);
    }

	if (deadbeef->fread((void *)data,1,4,f) != 4)
	{
		deadbeef->fclose(f);
		return NULL;
	}
	deadbeef->fclose(f);

	if (memcmp(data,MAGIC,4)) {
        trace ("shn: invalid MAGIC\n");
		return NULL;
    }

    shn_init_config ();
	if (!(tmp_file = load_shn(fname))) {
        trace ("shn: load_shn failed\n");
		return NULL;
    }

	DB_playItem_t *it = deadbeef->pl_item_alloc_init (fname, plugin.plugin.id);
    deadbeef->pl_add_meta (it, ":FILETYPE", "Shorten");
    deadbeef->plt_set_item_duration (plt, it, tmp_file->wave_header.length);

    int apeerr = deadbeef->junk_apev2_read (it, tmp_file->vars.fd);
    int v2err = deadbeef->junk_id3v2_read (it, tmp_file->vars.fd);
    int v1err = deadbeef->junk_id3v1_read (it, tmp_file->vars.fd);

	shn_unload(tmp_file);

    char s[100];
    snprintf (s, sizeof (s), "%lld", fsize);
    deadbeef->pl_add_meta (it, ":FILE_SIZE", s);
    snprintf (s, sizeof (s), "%d", tmp_file->wave_header.bits_per_sample);
    deadbeef->pl_add_meta (it, ":BPS", s);
    snprintf (s, sizeof (s), "%d", tmp_file->wave_header.channels);
    deadbeef->pl_add_meta (it, ":CHANNELS", s);
    snprintf (s, sizeof (s), "%d", tmp_file->wave_header.samples_per_sec);
    deadbeef->pl_add_meta (it, ":SAMPLERATE", s);
    int br = (int)roundf(fsize / (float)tmp_file->wave_header.length * 8 / 1000);
    snprintf (s, sizeof (s), "%d", br);
    deadbeef->pl_add_meta (it, ":BITRATE", s);
    deadbeef->pl_add_meta (it, "title", NULL);

    after = deadbeef->plt_insert_item (plt, after, it);
    deadbeef->pl_item_unref (it);
    return after;
}

#define CAPMAXSCHAR(x)  ((x > 127) ? 127 : x)
#define CAPMAXUCHAR(x)  ((x > 255) ? 255 : x)
#define CAPMAXSHORT(x)  ((x > 32767) ? 32767 : x)
#define CAPMAXUSHORT(x) ((x > 65535) ? 65535 : x)

static int sizeof_sample[TYPE_EOF];

void init_sizeof_sample() {
    sizeof_sample[TYPE_AU1]   = sizeof(uchar);
    sizeof_sample[TYPE_S8]    = sizeof(schar);
    sizeof_sample[TYPE_U8]    = sizeof(uchar);
    sizeof_sample[TYPE_S16HL] = sizeof(ushort);
    sizeof_sample[TYPE_U16HL] = sizeof(ushort);
    sizeof_sample[TYPE_S16LH] = sizeof(ushort);
    sizeof_sample[TYPE_U16LH] = sizeof(ushort);
    sizeof_sample[TYPE_ULAW]  = sizeof(uchar);
    sizeof_sample[TYPE_AU2]   = sizeof(uchar);
    sizeof_sample[TYPE_AU3]   = sizeof(uchar);
    sizeof_sample[TYPE_ALAW]  = sizeof(uchar);
}


/***************/
/* fixed write */
/***************/

void fwrite_type_init(shn_file *this_shn) {
    init_sizeof_sample();
    this_shn->decode_state->writebuf  = (schar*) NULL;
    this_shn->decode_state->writefub  = (schar*) NULL;
    this_shn->decode_state->nwritebuf = 0;
}

void fwrite_type_quit(shn_file *this_shn) {
    if(this_shn->decode_state->writebuf != NULL) {
        free(this_shn->decode_state->writebuf);
        this_shn->decode_state->writebuf = NULL;
    }
    if(this_shn->decode_state->writefub != NULL) {
        free(this_shn->decode_state->writefub);
        this_shn->decode_state->writefub = NULL;
    }
}

/* convert from signed ints to a given type and write */
void fwrite_type(slong **data,int ftype,int nchan,int nitem,shn_file *this_shn)
{
    int hiloint = 1, hilo = !(*((char*) &hiloint));
    int i, nwrite = 0, datasize = sizeof_sample[ftype], chan;
    slong *data0 = data[0];
    int bufAvailable = OUT_BUFFER_SIZE - this_shn->vars.bytes_in_buf;

    if(this_shn->decode_state->nwritebuf < nchan * nitem * datasize) {
        this_shn->decode_state->nwritebuf = nchan * nitem * datasize;
        if(this_shn->decode_state->writebuf != NULL) free(this_shn->decode_state->writebuf);
        if(this_shn->decode_state->writefub != NULL) free(this_shn->decode_state->writefub);
        this_shn->decode_state->writebuf = (schar*) pmalloc((ulong) this_shn->decode_state->nwritebuf,this_shn);
        if (!this_shn->decode_state->writebuf)
            return;
        this_shn->decode_state->writefub = (schar*) pmalloc((ulong) this_shn->decode_state->nwritebuf,this_shn);
        if (!this_shn->decode_state->writefub)
            return;
    }

    switch(ftype) {
    case TYPE_AU1: /* leave the conversion to fix_bitshift() */
    case TYPE_AU2: {
                       uchar *writebufp = (uchar*) this_shn->decode_state->writebuf;
                       if(nchan == 1)
                           for(i = 0; i < nitem; i++)
                               *writebufp++ = data0[i];
                       else
                           for(i = 0; i < nitem; i++)
                               for(chan = 0; chan < nchan; chan++)
                                   *writebufp++ = data[chan][i];
                       break;
                   }
    case TYPE_U8: {
                      uchar *writebufp = (uchar*) this_shn->decode_state->writebuf;
                      if(nchan == 1)
                          for(i = 0; i < nitem; i++)
                              *writebufp++ = CAPMAXUCHAR(data0[i]);
                      else
                          for(i = 0; i < nitem; i++)
                              for(chan = 0; chan < nchan; chan++)
                                  *writebufp++ =  CAPMAXUCHAR(data[chan][i]);
                      break;
                  }
    case TYPE_S8: {
                      schar *writebufp = (schar*) this_shn->decode_state->writebuf;
                      if(nchan == 1)
                          for(i = 0; i < nitem; i++)
                              *writebufp++ = CAPMAXSCHAR(data0[i]);
                      else
                          for(i = 0; i < nitem; i++)
                              for(chan = 0; chan < nchan; chan++)
                                  *writebufp++ = CAPMAXSCHAR(data[chan][i]);
                      break;
                  }
    case TYPE_S16HL:
    case TYPE_S16LH: {
                         short *writebufp = (short*) this_shn->decode_state->writebuf;
                         if(nchan == 1)
                             for(i = 0; i < nitem; i++)
                                 *writebufp++ = CAPMAXSHORT(data0[i]);
                         else
                             for(i = 0; i < nitem; i++)
                                 for(chan = 0; chan < nchan; chan++)
                                     *writebufp++ = CAPMAXSHORT(data[chan][i]);
                         break;
                     }
    case TYPE_U16HL:
    case TYPE_U16LH: {
                         ushort *writebufp = (ushort*) this_shn->decode_state->writebuf;
                         if(nchan == 1)
                             for(i = 0; i < nitem; i++)
                                 *writebufp++ = CAPMAXUSHORT(data0[i]);
                         else
                             for(i = 0; i < nitem; i++)
                                 for(chan = 0; chan < nchan; chan++)
                                     *writebufp++ = CAPMAXUSHORT(data[chan][i]);
                         break;
                     }
    case TYPE_ULAW: {
                        uchar *writebufp = (uchar*) this_shn->decode_state->writebuf;
                        if(nchan == 1)
                            for(i = 0; i < nitem; i++)
                                *writebufp++ = Slinear2ulaw(CAPMAXSHORT((data0[i] << 3)));
                        else
                            for(i = 0; i < nitem; i++)
                                for(chan = 0; chan < nchan; chan++)
                                    *writebufp++ = Slinear2ulaw(CAPMAXSHORT((data[chan][i] << 3)));
                        break;
                    }
    case TYPE_AU3: {
                       uchar *writebufp = (uchar*) this_shn->decode_state->writebuf;
                       if(nchan == 1)
                           for(i = 0; i < nitem; i++)
                               if(data0[i] < 0)
                                   *writebufp++ = (127 - data0[i]) ^ 0xd5;
                               else
                                   *writebufp++ = (data0[i] + 128) ^ 0x55;
                       else
                           for(i = 0; i < nitem; i++)
                               for(chan = 0; chan < nchan; chan++)
                                   if(data[chan][i] < 0)
                                       *writebufp++ = (127 - data[chan][i]) ^ 0xd5;
                                   else
                                       *writebufp++ = (data[chan][i] + 128) ^ 0x55;
                       break;
                   }
    case TYPE_ALAW: {
                        uchar *writebufp = (uchar*) this_shn->decode_state->writebuf;
                        if(nchan == 1)
                            for(i = 0; i < nitem; i++)
                                *writebufp++ = Slinear2alaw(CAPMAXSHORT((data0[i] << 3)));
                        else
                            for(i = 0; i < nitem; i++)
                                for(chan = 0; chan < nchan; chan++)
                                    *writebufp++ = Slinear2alaw(CAPMAXSHORT((data[chan][i] << 3)));
                        break;
                    }
    }

    switch(ftype) {
    case TYPE_AU1:
    case TYPE_S8:
    case TYPE_U8:
    case TYPE_ULAW:
    case TYPE_AU2:
    case TYPE_AU3:
    case TYPE_ALAW:
        if (datasize*nchan*nitem <= bufAvailable) {
            memcpy((void *)&this_shn->vars.buffer[this_shn->vars.bytes_in_buf],(const void *)this_shn->decode_state->writebuf,datasize*nchan*nitem);
            this_shn->vars.bytes_in_buf += datasize*nchan*nitem;
            nwrite = nitem;
        }
        else
            shn_debug("Buffer overrun in fwrite_type() [case 1]: %d bytes to read, but only %d bytes are available",datasize*nchan*nitem,bufAvailable);
        break;
    case TYPE_S16HL:
    case TYPE_U16HL:
        if(hilo)
        {
            if (datasize*nchan*nitem <= bufAvailable) {
                memcpy((void *)&this_shn->vars.buffer[this_shn->vars.bytes_in_buf],(const void *)this_shn->decode_state->writebuf,datasize*nchan*nitem);
                this_shn->vars.bytes_in_buf += datasize*nchan*nitem;
                nwrite = nitem;
            }
            else
                shn_debug("Buffer overrun in fwrite_type() [case 2]: %d bytes to read, but only %d bytes are available",datasize*nchan*nitem,bufAvailable);
        }
        else
        {
            swab(this_shn->decode_state->writebuf, this_shn->decode_state->writefub, datasize * nchan * nitem);
            if (datasize*nchan*nitem <= bufAvailable) {
                memcpy((void *)&this_shn->vars.buffer[this_shn->vars.bytes_in_buf],(const void *)this_shn->decode_state->writefub,datasize*nchan*nitem);
                this_shn->vars.bytes_in_buf += datasize*nchan*nitem;
                nwrite = nitem;
            }
            else
                shn_debug("Buffer overrun in fwrite_type() [case 3]: %d bytes to read, but only %d bytes are available",datasize*nchan*nitem,bufAvailable);
        }
        break;
    case TYPE_S16LH:
    case TYPE_U16LH:
        if(hilo)
        {
            swab(this_shn->decode_state->writebuf, this_shn->decode_state->writefub, datasize * nchan * nitem);
            if (datasize*nchan*nitem <= bufAvailable) {
                memcpy((void *)&this_shn->vars.buffer[this_shn->vars.bytes_in_buf],(const void *)this_shn->decode_state->writefub,datasize*nchan*nitem);
                this_shn->vars.bytes_in_buf += datasize*nchan*nitem;
                nwrite = nitem;
            }
            else
                shn_debug("Buffer overrun in fwrite_type() [case 4]: %d bytes to read, but only %d bytes are available",datasize*nchan*nitem,bufAvailable);
        }
        else
        {
            if (datasize*nchan*nitem <= bufAvailable) {
                memcpy((void *)&this_shn->vars.buffer[this_shn->vars.bytes_in_buf],(const void *)this_shn->decode_state->writebuf,datasize*nchan*nitem);
                this_shn->vars.bytes_in_buf += datasize*nchan*nitem;
                nwrite = nitem;
            }
            else
                shn_debug("Buffer overrun in fwrite_type() [case 5]: %d bytes to read, but only %d bytes are available",datasize*nchan*nitem,bufAvailable);
        }
        break;
    }

    if(nwrite != nitem)
        shn_error_fatal(this_shn,"Failed to write decompressed stream -\npossible corrupt or truncated file");
}

/*************/
/* bitshifts */
/*************/

void fix_bitshift(buffer, nitem, bitshift, ftype) slong *buffer; int nitem,
       bitshift, ftype; {
  int i;

  if(ftype == TYPE_AU1)
    for(i = 0; i < nitem; i++)
      buffer[i] = ulaw_outward[bitshift][buffer[i] + 128];
  else if(ftype == TYPE_AU2)
    for(i = 0; i < nitem; i++) {
      if(buffer[i] >= 0)
	buffer[i] = ulaw_outward[bitshift][buffer[i] + 128];
      else if(buffer[i] == -1)
	buffer[i] =  NEGATIVE_ULAW_ZERO;
      else
	buffer[i] = ulaw_outward[bitshift][buffer[i] + 129];
    }
  else
    if(bitshift != 0)
      for(i = 0; i < nitem; i++)
	buffer[i] <<= bitshift;
}

int get_wave_header(shn_file *this_shn)
{
    slong  **buffer = NULL, **offset = NULL;
    slong  lpcqoffset = 0;
    int   version = FORMAT_VERSION, bitshift = 0;
    int   ftype = TYPE_EOF;
    char  *magic = MAGIC;
    int   blocksize = DEFAULT_BLOCK_SIZE, nchan = DEFAULT_NCHAN;
    int   i, chan, nwrap, nskip = DEFAULT_NSKIP;
    int   *qlpc = NULL, maxnlpc = DEFAULT_MAXNLPC, nmean = UNDEFINED_UINT;
    int   cmd;
    int   internal_ftype;
    int   cklen;
    int   retval = 0;

    if (!init_decode_state(this_shn))
        return 0;

    /***********************/
    /* EXTRACT starts here */
    /***********************/

    /* read magic number */
#ifdef STRICT_FORMAT_COMPATABILITY
    if(FORMAT_VERSION < 2)
    {
        for(i = 0; i < strlen(magic); i++) {
            if(getc_exit(this_shn->vars.fd) != magic[i])
                return 0;
            this_shn->vars.bytes_read++;
        }

        /* get version number */
        version = getc_exit(this_shn->vars.fd);
        this_shn->vars.bytes_read++;
    }
    else
#endif /* STRICT_FORMAT_COMPATABILITY */
    {
        int nscan = 0;

        version = MAX_VERSION + 1;
        while(version > MAX_VERSION)
        {
            int byte = ddb_getc(this_shn->vars.fd);
            this_shn->vars.bytes_read++;
            if(byte == EOF)
                return 0;
            if(magic[nscan] != '\0' && byte == magic[nscan])
                nscan++;
            else
                if(magic[nscan] == '\0' && byte <= MAX_VERSION)
                    version = byte;
                else
                {
                    if(byte == magic[0])
                        nscan = 1;
                    else
                    {
                        nscan = 0;
                    }
                    version = MAX_VERSION + 1;
                }
        }
    }

    /* check version number */
    if(version > MAX_SUPPORTED_VERSION)
        return 0;

    /* set up the default nmean, ignoring the command line state */
    nmean = (version < 2) ? DEFAULT_V0NMEAN : DEFAULT_V2NMEAN;

    /* initialise the variable length file read for the compressed stream */
    var_get_init(this_shn);
    if (this_shn->vars.fatal_error)
        return 0;

    /* initialise the fixed length file write for the uncompressed stream */
    fwrite_type_init(this_shn);

    /* get the internal file type */
    internal_ftype = UINT_GET(TYPESIZE, this_shn);

    /* has the user requested a change in file type? */
    if(internal_ftype != ftype) {
        if(ftype == TYPE_EOF) {
            ftype = internal_ftype;    /*  no problems here */
        }
        else {           /* check that the requested conversion is valid */
            if(internal_ftype == TYPE_AU1 || internal_ftype == TYPE_AU2 ||
                    internal_ftype == TYPE_AU3 || ftype == TYPE_AU1 ||ftype == TYPE_AU2 || ftype == TYPE_AU3)
            {
                retval = 0;
                goto got_enough_data;
            }
        }
    }

    nchan = UINT_GET(CHANSIZE, this_shn);
    this_shn->vars.actual_nchan = nchan;

    /* get blocksize if version > 0 */
    if(version > 0)
    {
        int byte;
        blocksize = UINT_GET((int) (log((double) DEFAULT_BLOCK_SIZE) / M_LN2),this_shn);
        maxnlpc = UINT_GET(LPCQSIZE, this_shn);
        this_shn->vars.actual_maxnlpc = maxnlpc;
        nmean = UINT_GET(0, this_shn);
        this_shn->vars.actual_nmean = nmean;
        nskip = UINT_GET(NSKIPSIZE, this_shn);
        for(i = 0; i < nskip; i++)
        {
            byte = uvar_get(XBYTESIZE,this_shn);
        }
    }
    else
        blocksize = DEFAULT_BLOCK_SIZE;

    nwrap = MAX(NWRAP, maxnlpc);

    /* grab some space for the input buffer */
    buffer  = long2d((ulong) nchan, (ulong) (blocksize + nwrap),this_shn);
    if (this_shn->vars.fatal_error)
        return 0;
    offset  = long2d((ulong) nchan, (ulong) MAX(1, nmean),this_shn);
    if (this_shn->vars.fatal_error) {
        if (buffer) {
            free(buffer);
            buffer = NULL;
        }
        return 0;
    }

    for(chan = 0; chan < nchan; chan++)
    {
        for(i = 0; i < nwrap; i++)
            buffer[chan][i] = 0;
        buffer[chan] += nwrap;
    }

    if(maxnlpc > 0) {
        qlpc = (int*) pmalloc((ulong) (maxnlpc * sizeof(*qlpc)),this_shn);
        if (this_shn->vars.fatal_error) {
            if (buffer) {
                free(buffer);
                buffer = NULL;
            }
            if (offset) {
                free(offset);
                buffer = NULL;
            }
            return 0;
        }
    }

    if(version > 1)
        lpcqoffset = V2LPCQOFFSET;

    init_offset(offset, nchan, MAX(1, nmean), internal_ftype);

    /* get commands from file and execute them */
    chan = 0;
    while(1)
    {
        this_shn->vars.reading_function_code = 1;
        cmd = uvar_get(FNSIZE,this_shn);
        this_shn->vars.reading_function_code = 0;

        switch(cmd)
        {
        case FN_ZERO:
        case FN_DIFF0:
        case FN_DIFF1:
        case FN_DIFF2:
        case FN_DIFF3:
        case FN_QLPC:
            {
                slong coffset, *cbuffer = buffer[chan];
                int resn = 0, nlpc, j;

                if(cmd != FN_ZERO)
                {
                    resn = uvar_get(ENERGYSIZE,this_shn);
                    if (this_shn->vars.fatal_error) {
                        retval = 0;
                        goto got_enough_data;
                    }
                    /* this is a hack as version 0 differed in definition of var_get */
                    if(version == 0)
                        resn--;
                }

                /* find mean offset : N.B. this code duplicated */
                if(nmean == 0)
                    coffset = offset[chan][0];
                else
                {
                    slong sum = (version < 2) ? 0 : nmean / 2;
                    for(i = 0; i < nmean; i++)
                        sum += offset[chan][i];
                    if(version < 2)
                        coffset = sum / nmean;
                    else
                        coffset = ROUNDEDSHIFTDOWN(sum / nmean, bitshift);
                }

                switch(cmd)
                {
                case FN_ZERO:
                    for(i = 0; i < blocksize; i++)
                        cbuffer[i] = 0;
                    break;
                case FN_DIFF0:
                    for(i = 0; i < blocksize; i++) {
                        cbuffer[i] = var_get(resn,this_shn) + coffset;
                        if (this_shn->vars.fatal_error) {
                            retval = 0;
                            goto got_enough_data;
                        }
                    }
                    break;
                case FN_DIFF1:
                    for(i = 0; i < blocksize; i++) {
                        cbuffer[i] = var_get(resn,this_shn) + cbuffer[i - 1];
                        if (this_shn->vars.fatal_error) {
                            retval = 0;
                            goto got_enough_data;
                        }
                    }
                    break;
                case FN_DIFF2:
                    for(i = 0; i < blocksize; i++) {
                        cbuffer[i] = var_get(resn,this_shn) + (2 * cbuffer[i - 1] -	cbuffer[i - 2]);
                        if (this_shn->vars.fatal_error) {
                            retval = 0;
                            goto got_enough_data;
                        }
                    }
                    break;
                case FN_DIFF3:
                    for(i = 0; i < blocksize; i++) {
                        cbuffer[i] = var_get(resn,this_shn) + 3 * (cbuffer[i - 1] -  cbuffer[i - 2]) + cbuffer[i - 3];
                        if (this_shn->vars.fatal_error) {
                            retval = 0;
                            goto got_enough_data;
                        }
                    }
                    break;
                case FN_QLPC:
                    nlpc = uvar_get(LPCQSIZE,this_shn);
                    if (this_shn->vars.fatal_error) {
                        retval = 0;
                        goto got_enough_data;
                    }

                    for(i = 0; i < nlpc; i++) {
                        qlpc[i] = var_get(LPCQUANT,this_shn);
                        if (this_shn->vars.fatal_error) {
                            retval = 0;
                            goto got_enough_data;
                        }
                    }
                    for(i = 0; i < nlpc; i++)
                        cbuffer[i - nlpc] -= coffset;
                    for(i = 0; i < blocksize; i++)
                    {
                        slong sum = lpcqoffset;

                        for(j = 0; j < nlpc; j++)
                            sum += qlpc[j] * cbuffer[i - j - 1];
                        cbuffer[i] = var_get(resn,this_shn) + (sum >> LPCQUANT);
                        if (this_shn->vars.fatal_error) {
                            retval = 0;
                            goto got_enough_data;
                        }
                    }
                    if(coffset != 0)
                        for(i = 0; i < blocksize; i++)
                            cbuffer[i] += coffset;
                    break;
                }

                /* store mean value if appropriate : N.B. Duplicated code */
                if(nmean > 0)
                {
                    slong sum = (version < 2) ? 0 : blocksize / 2;

                    for(i = 0; i < blocksize; i++)
                        sum += cbuffer[i];

                    for(i = 1; i < nmean; i++)
                        offset[chan][i - 1] = offset[chan][i];
                    if(version < 2)
                        offset[chan][nmean - 1] = sum / blocksize;
                    else
                        offset[chan][nmean - 1] = (sum / blocksize) << bitshift;
                }

                if (0 == chan) {
                    this_shn->vars.initial_file_position = this_shn->vars.last_file_position_no_really;
                    goto got_enough_data;
                }

                /* do the wrap */
                for(i = -nwrap; i < 0; i++)
                    cbuffer[i] = cbuffer[i + blocksize];

                fix_bitshift(cbuffer, blocksize, bitshift, internal_ftype);

                if(chan == nchan - 1)
                {
                    fwrite_type(buffer, ftype, nchan, blocksize, this_shn);
                    this_shn->vars.bytes_in_buf = 0;
                }

                chan = (chan + 1) % nchan;
                break;
            }
            break;

        case FN_BLOCKSIZE:
            UINT_GET((int) (log((double) blocksize) / M_LN2), this_shn);
            break;

        case FN_VERBATIM:
            cklen = uvar_get(VERBATIM_CKSIZE_SIZE,this_shn);

            while (cklen--) {
                if (this_shn->vars.bytes_in_header >= OUT_BUFFER_SIZE) {
                    shn_debug("Unexpectedly large header - " PACKAGE " can only handle a maximum of %d bytes",OUT_BUFFER_SIZE);
                    goto got_enough_data;
                }
                this_shn->vars.bytes_in_buf = 0;
                this_shn->vars.header[this_shn->vars.bytes_in_header++] = (char)uvar_get(VERBATIM_BYTE_SIZE,this_shn);
            }
            retval = 1;
            break;

        case FN_BITSHIFT:
            bitshift = uvar_get(BITSHIFTSIZE,this_shn);
            this_shn->vars.actual_bitshift = bitshift;
            break;

        default:
            goto got_enough_data;
        }
    }

got_enough_data:

    /* wind up */
    var_get_quit(this_shn);
    fwrite_type_quit(this_shn);

    if (buffer) free((void *) buffer);
    if (offset) free((void *) offset);
    if(maxnlpc > 0 && qlpc)
        free((void *) qlpc);

    this_shn->vars.bytes_in_buf = 0;

    return retval;
}

void shn_unload(shn_file *this_shn)
{
	if (this_shn)
	{
		if (this_shn->vars.fd)
		{
			deadbeef->fclose(this_shn->vars.fd);
			this_shn->vars.fd = NULL;
		}

		if (this_shn->decode_state)
		{
			if (this_shn->decode_state->getbuf)
			{
				free(this_shn->decode_state->getbuf);
				this_shn->decode_state->getbuf = NULL;
			}

			if (this_shn->decode_state->writebuf)
			{
				free(this_shn->decode_state->writebuf);
				this_shn->decode_state->writebuf = NULL;
			}

			if (this_shn->decode_state->writefub)
			{
				free(this_shn->decode_state->writefub);
				this_shn->decode_state->writefub = NULL;
			}

			free(this_shn->decode_state);
			this_shn->decode_state = NULL;
		}

		if (this_shn->seek_table)
		{
			free(this_shn->seek_table);
			this_shn->seek_table = NULL;
		}

		free(this_shn);
		this_shn = NULL;
	}
}

shn_file *load_shn(const char *filename)
{
	shn_file *tmp_file;
    shn_seek_entry *first_seek_table;

	shn_debug("Loading file: '%s'",filename);

	if (!(tmp_file = malloc(sizeof(shn_file))))
	{
		shn_debug("Could not allocate memory for SHN data structure");
		return NULL;
	}

	memset(tmp_file, 0, sizeof(shn_file));

	tmp_file->vars.fd = NULL;
	tmp_file->vars.seek_to = -1;
	tmp_file->vars.eof = 0;
	tmp_file->vars.going = 0;
	tmp_file->vars.seek_table_entries = NO_SEEK_TABLE;
	tmp_file->vars.bytes_in_buf = 0;
	tmp_file->vars.bytes_in_header = 0;
	tmp_file->vars.reading_function_code = 0;
	tmp_file->vars.initial_file_position = 0;
	tmp_file->vars.last_file_position = 0;
	tmp_file->vars.last_file_position_no_really = 0;
	tmp_file->vars.bytes_read = 0;
	tmp_file->vars.actual_bitshift = 0;
	tmp_file->vars.actual_maxnlpc = 0;
	tmp_file->vars.actual_nmean = 0;
	tmp_file->vars.actual_nchan = 0;
	tmp_file->vars.seek_offset = 0;

	tmp_file->decode_state = NULL;

	tmp_file->wave_header.filename = filename;
	tmp_file->wave_header.wave_format = 0;
	tmp_file->wave_header.channels = 0;
	tmp_file->wave_header.block_align = 0;
	tmp_file->wave_header.bits_per_sample = 0;
	tmp_file->wave_header.samples_per_sec = 0;
	tmp_file->wave_header.avg_bytes_per_sec = 0;
	tmp_file->wave_header.rate = 0;
	tmp_file->wave_header.header_size = 0;
	tmp_file->wave_header.data_size = 0;
	tmp_file->wave_header.file_has_id3v2_tag = 0;
	tmp_file->wave_header.id3v2_tag_size = 0;

	tmp_file->seek_header.version = NO_SEEK_TABLE;
	tmp_file->seek_header.shnFileSize = 0;

	tmp_file->seek_trailer.seekTableSize = 0;

	tmp_file->seek_table = NULL;

    tmp_file->vars.fd = deadbeef->fopen (filename);
    if (!tmp_file->vars.fd) {
		shn_debug("Could not open file: '%s'",filename);
		shn_unload(tmp_file);
		return NULL;
    }

    tmp_file->wave_header.id3v2_tag_size = deadbeef->junk_get_leading_size (tmp_file->vars.fd);
    if (tmp_file->wave_header.id3v2_tag_size > 0) {
        tmp_file->wave_header.file_has_id3v2_tag = 2;
        trace ("found id3v2 tag, size: %d\n", tmp_file->wave_header.id3v2_tag_size);
        if (0 != deadbeef->fseek(tmp_file->vars.fd,(long)tmp_file->wave_header.id3v2_tag_size,SEEK_SET)) {
            shn_debug("Error while discarding ID3v2 tag in file '%s'.",filename);
            deadbeef->rewind (tmp_file->vars.fd);
        }
    }

	if (0 == get_wave_header(tmp_file))
	{
		shn_debug("Unable to read WAVE header from file '%s'",filename);
		shn_unload(tmp_file);
		return NULL;
	}

	if (tmp_file->wave_header.file_has_id3v2_tag)
	{
		deadbeef->fseek(tmp_file->vars.fd,tmp_file->wave_header.id3v2_tag_size,SEEK_SET);
		tmp_file->vars.bytes_read += tmp_file->wave_header.id3v2_tag_size;
		tmp_file->vars.seek_offset = tmp_file->wave_header.id3v2_tag_size;
	}
    else
	{
		deadbeef->fseek(tmp_file->vars.fd,0,SEEK_SET);
	}

	if (0 == shn_verify_header(tmp_file))
	{
		shn_debug("Invalid WAVE header in file: '%s'",filename);
		shn_unload(tmp_file);
		return NULL;
	}

	if (tmp_file->decode_state)
	{
		free(tmp_file->decode_state);
		tmp_file->decode_state = NULL;
	}

	shn_load_seek_table(tmp_file,filename);

	if (NO_SEEK_TABLE != tmp_file->vars.seek_table_entries)
	{
		/* verify seek tables */

		first_seek_table = (shn_seek_entry *)tmp_file->seek_table;

		if (tmp_file->vars.actual_bitshift != shn_uchar_to_ushort_le(first_seek_table->data+22))
		{
			/* initial bitshift value in the file does not match the first bitshift value of the first seektable entry - seeking is broken */
			shn_debug("Broken seek table detected (invalid bitshift) - seeking disabled for this file.");
			tmp_file->vars.seek_table_entries = NO_SEEK_TABLE;
		}
		else if (tmp_file->vars.actual_nchan > 2)
		{
			/* nchan is greater than the number of such entries stored in a seek table entry - seeking won't work */
			shn_debug("Broken seek table detected (nchan %d not in range [1 .. 2]) - seeking disabled for this file.",tmp_file->vars.actual_nchan);
			tmp_file->vars.seek_table_entries = NO_SEEK_TABLE;
		}
		else if (tmp_file->vars.actual_maxnlpc > 3)
		{
			/* maxnlpc is greater than the number of such entries stored in a seek table entry - seeking won't work */
			shn_debug("Broken seek table detected (maxnlpc %d not in range [0 .. 3]) - seeking disabled for this file.",tmp_file->vars.actual_maxnlpc);
			tmp_file->vars.seek_table_entries = NO_SEEK_TABLE;
		}
		else if (tmp_file->vars.actual_nmean > 4)
		{
			/* nmean is greater than the number of such entries stored in a seek table entry - seeking won't work */
			shn_debug("Broken seek table detected (nmean %d not in range [0 .. 4]) - seeking disabled for this file.",tmp_file->vars.actual_nmean);
			tmp_file->vars.seek_table_entries = NO_SEEK_TABLE;
		}
		else
		{
			/* seek table appears to be valid - now adjust byte offsets in seek table to match the file */
			tmp_file->vars.seek_offset += tmp_file->vars.initial_file_position - shn_uchar_to_ulong_le(first_seek_table->data+8);

			if (0 != tmp_file->vars.seek_offset)
			{
				shn_debug("Adjusting seek table offsets by %ld bytes due to mismatch between seek table values and input file - seeking might not work correctly.",
					tmp_file->vars.seek_offset);
			}
		}
	}

	shn_debug("Successfully loaded file: '%s'",filename);

	return tmp_file;
}

#if 0
void write_and_wait(shn_file *this_shn,int block_size)
{
	int bytes_to_write,bytes_in_block,i;

	if (this_shn->vars.bytes_in_buf < block_size)
		return;

	bytes_in_block = min(this_shn->vars.bytes_in_buf, block_size);

	if (bytes_in_block <= 0)
		return;

	bytes_to_write = bytes_in_block;
	while ((bytes_to_write + bytes_in_block) <= this_shn->vars.bytes_in_buf)
		bytes_to_write += bytes_in_block;

	shn_ip.add_vis_pcm(shn_ip.output->written_time(), (this_shn->wave_header.bits_per_sample == 16) ? FMT_S16_LE : FMT_U8,
		this_shn->wave_header.channels, bytes_to_write, this_shn->vars.buffer);

	while(shn_ip.output->buffer_free() < bytes_to_write && this_shn->vars.going && this_shn->vars.seek_to == -1)
		xmms_usleep(10000);

	if(this_shn->vars.going && this_shn->vars.seek_to == -1) {
		if (shn_cfg.swap_bytes)
			swap_bytes(this_shn, bytes_to_write);
		shn_ip.output->write_audio(this_shn->vars.buffer, bytes_to_write);
	} else
		return;

	/* shift data from end of buffer to the front */
	this_shn->vars.bytes_in_buf -= bytes_to_write;

	for(i=0;i<this_shn->vars.bytes_in_buf;i++)
		this_shn->vars.buffer[i] = this_shn->vars.buffer[i+bytes_to_write];
}
#endif

static const char * exts[] = { "shn", NULL };

static const char settings_dlg[] =
    "property \"Relative seek table path\" entry shn.relative_seektable_path seektables;\n"
    "property \"Absolute seek table path\" entry shn.seektable_path \"\";\n"
    "property \"Swap audio bytes (toggle if all you hear is static)\" checkbox shn.swap_bytes 0;\n"
;

// define plugin interface
static DB_decoder_t plugin = {
    .plugin.api_vmajor = 1,
    .plugin.api_vminor = 0,
    .plugin.version_major = 1,
    .plugin.version_minor = 0,
    .plugin.type = DB_PLUGIN_DECODER,
    .plugin.id = "shn",
    .plugin.name = "Shorten player",
    .plugin.descr = "decodes shn files",
    .plugin.copyright = 
        "Copyright (C) 2009-2011 Alexey Yakovenko <waker@users.sourceforge.net>\n"
        "\n"
        "Based on xmms-shn, http://www.etree.org/shnutils/xmms-shn/\n"
        "Copyright (C) 2000-2007  Jason Jordan <shnutils@freeshell.org>\n"
        "\n"
        "This program is free software; you can redistribute it and/or\n"
        "modify it under the terms of the GNU General Public License\n"
        "as published by the Free Software Foundation; either version 2\n"
        "of the License, or (at your option) any later version.\n"
        "\n"
        "This program is distributed in the hope that it will be useful,\n"
        "but WITHOUT ANY WARRANTY; without even the implied warranty of\n"
        "MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n"
        "GNU General Public License for more details.\n"
        "\n"
        "You should have received a copy of the GNU General Public License\n"
        "along with this program; if not, write to the Free Software\n"
        "Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.\n"
    ,
    .plugin.website = "http://deadbeef.sf.net",
    .plugin.configdialog = settings_dlg,
    .open = shn_open,
    .init = shn_init,
    .free = shn_free,
    .read = shn_read,
    .seek = shn_seek,
    .seek_sample = shn_seek_sample,
    .insert = shn_insert,
    .exts = exts,
};

DB_plugin_t *
ddb_shn_load (DB_functions_t *api) {
    deadbeef = api;
    return DB_PLUGIN (&plugin);
}