/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2015             *
 * by the Xiph.Org Foundation http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

 function: single-block PCM synthesis
 last mod: $Id: synthesis.c 19441 2015-01-21 01:17:41Z xiphmont $

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

#include <string.h>
#include "registry.h"
#include "misc.h"

int vorbis_synthesis(vorbis_block *vb,ogg_packet *op){
  vorbis_dsp_state     *vd= vb ? vb->vd : 0;
  private_state        *b= vd ? vd->backend_state : 0;
  vorbis_info          *vi= vd ? vd->vi : 0;
  codec_setup_info     *ci= vi ? vi->codec_setup : 0;
  oggpack_buffer       *opb=vb ? &vb->opb : 0;
  int                   type,mode,i;

  if (!vd || !b || !vi || !ci || !opb) {
    return OV_EBADPACKET;
  }

  /* first things first.  Make sure decode is ready */
  _vorbis_block_ripcord(vb);
  oggpack_readinit(opb,op->packet,op->bytes);

  /* Check the packet type */
  if(oggpack_read(opb,1)!=0){
    /* Oops.  This is not an audio data packet */
    return(OV_ENOTAUDIO);
  }

  /* read our mode and pre/post windowsize */
  mode=oggpack_read(opb,b->modebits);
  if(mode==-1){
    return(OV_EBADPACKET);
  }

  vb->mode=mode;
  if(!ci->mode_param[mode]){
    return(OV_EBADPACKET);
  }

  vb->W=ci->mode_param[mode]->blockflag;
  if(vb->W){

    /* this doesn;t get mapped through mode selection as it's used
       only for window selection */
    vb->lW=oggpack_read(opb,1);
    vb->nW=oggpack_read(opb,1);
    if(vb->nW==-1){
      return(OV_EBADPACKET);
    }
  }else{
    vb->lW=0;
    vb->nW=0;
  }

  /* more setup */
  vb->granulepos=op->granulepos;
  vb->sequence=op->packetno;
  vb->eofflag=op->e_o_s;

  /* alloc pcm passback storage */
  vb->pcmend=ci->blocksizes[vb->W];
  vb->pcm=_vorbis_block_alloc(vb,sizeof(*vb->pcm)*vi->channels);
  if (!vb->pcm) return (OV_EMEMORY);
  memset(vb->pcm,0,sizeof(*vb->pcm)*vi->channels);
  for(i=0;i<vi->channels;i++)
  {
    vb->pcm[i]=_vorbis_block_alloc(vb,vb->pcmend*sizeof(*vb->pcm[i]));
    if (!vb->pcm[i]) return (OV_EMEMORY);
  }

  /* unpack_header enforces range checking */
  type=ci->map_type[ci->mode_param[mode]->mapping];

  return(_mapping_P[type]->inverse(vb,ci->map_param[ci->mode_param[mode]->
						   mapping]));
}


