/*  DecMPA decoding routines from Lame/HIP (Myers W. Carpenter)	

    This library 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 library 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 library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

	For more information look at the file License.txt in this package.

  
	email: hazard_hd@users.sourceforge.net
*/

//changes: 8/20/2002, Hauke Duden
//	- fixed potential access violation in check_vbr_header and sync_buffer

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdlib.h>
#include <stdio.h>

#include "common.h"
#include "interface.h"
#include "tabinit.h"
#include "layer3.h"
#include "VbrTag.h"

#ifdef USE_LAYER_1
	#include "layer1.h"
#endif

#ifdef USE_LAYER_2
	#include "layer2.h"
#endif

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif


BOOL InitMP3( PMPSTR mp) 
{
	memset(mp,0,sizeof(MPSTR));

	mp->framesize = 0;
        mp->num_frames = 0;
        mp->enc_delay = -1;
        mp->enc_padding = -1;
        mp->vbr_header=0;
	mp->header_parsed=0;
	mp->side_parsed=0;
	mp->data_parsed=0;
	mp->free_format=0;
	mp->old_free_format=0;
	mp->ssize = 0;
	mp->dsize=0;
	mp->fsizeold = -1;
	mp->bsize = 0;
	mp->head = mp->tail = NULL;
	mp->fr.single = -1;
	mp->bsnum = 0;
	wordpointer = mp->bsspace[mp->bsnum] + 512;
	mp->synth_bo = 1;
	mp->sync_bitstream = 1;

	make_decode_tables(32767);

	init_layer3(SBLIMIT);

#ifdef USE_LAYER_2
	init_layer2();
#endif

	return !0;
}

void ExitMP3( PMPSTR mp)
{
	struct buf *b,*bn;
	
	b = mp->tail;
	while(b) {
		free(b->pnt);
		bn = b->next;
		free(b);
		b = bn;
	}
}

static struct buf *addbuf( PMPSTR mp, unsigned char *buf,int size)
{
	struct buf *nbuf;

	nbuf = (struct buf*) malloc( sizeof(struct buf) );
	if(!nbuf) {
		//fprintf(stderr,"Out of memory!\n");
		return NULL;
	}
	nbuf->pnt = (unsigned char*) malloc((size_t)size);
	if(!nbuf->pnt) {
		free(nbuf);
		return NULL;
	}
	nbuf->size = size;
	memcpy(nbuf->pnt,buf,(size_t)size);
	nbuf->next = NULL;
	nbuf->prev = mp->head;
	nbuf->pos = 0;

	if(!mp->tail) {
		mp->tail = nbuf;
	}
	else {
	  mp->head->next = nbuf;
	}

	mp->head = nbuf;
	mp->bsize += size;

	return nbuf;
}

void remove_buf(PMPSTR mp)
{
  struct buf *buf = mp->tail;
  
  mp->tail = buf->next;
  if(mp->tail)
    mp->tail->prev = NULL;
  else {
    mp->tail = mp->head = NULL;
  }
  
  free(buf->pnt);
  free(buf);

}

static int read_buf_byte(PMPSTR mp)
{
	unsigned int b;

	int pos;

	
	pos = mp->tail->pos;
	while(pos >= mp->tail->size) {
	        remove_buf(mp);
		//if(!mp->tail) {
			//fprintf(stderr,"Fatal error! tried to read past mp buffer\n");
			//exit(1);
		//}
		pos = mp->tail->pos;
	}

	b = mp->tail->pnt[pos];
	mp->bsize--;
	mp->tail->pos++;
	

	return b;
}



static void read_head(PMPSTR mp)
{
	unsigned long head;

	head = read_buf_byte(mp);
	head <<= 8;
	head |= read_buf_byte(mp);
	head <<= 8;
	head |= read_buf_byte(mp);
	head <<= 8;
	head |= read_buf_byte(mp);

	mp->header = head;
}






void copy_mp(PMPSTR mp,int size,unsigned char *ptr) 
{
  int len = 0;

  while(len < size) {
    int nlen;
    int blen = mp->tail->size - mp->tail->pos;
    if( (size - len) <= blen) {
      nlen = size-len;
    }
    else {
      nlen = blen;
    }
    memcpy(ptr+len,mp->tail->pnt+mp->tail->pos,(size_t)nlen);
    len += nlen;
    mp->tail->pos += nlen;
    mp->bsize -= nlen;
    if(mp->tail->pos == mp->tail->size) {
      remove_buf(mp);
    }
  }
}

// number of bytes needed by GetVbrTag to parse header
#define XING_HEADER_SIZE 194

// traverse mp data structure without changing it
// (just like sync_buffer)
// pull out Xing bytes
// call vbr header check code from LAME
// if we find a header, parse it and also compute the VBR header size
// if no header, do nothing.
//
// bytes = number of bytes before MPEG header.  skip this many bytes
// before starting to read
// return value: number of bytes in VBR header, including syncword
int check_vbr_header(PMPSTR mp,int bytes)
{
  int i,pos;
  struct buf *buf=mp->tail;
  unsigned char xing[XING_HEADER_SIZE];
  VBRTAGDATA pTagData;

  pos = buf->pos;
  // skip to valid header
  for (i=0; i<bytes; ++i) {
    while(pos >= buf->size) {
      buf  = buf->next;
	  //fixed by Hauke Duden
	  //this has to be checked BEFORE accessing buf->pos
      if(!buf) 	return -1; /* fatal error */
	  pos = buf->pos;      
    }
    ++pos;
  }
  // now read header
  for (i=0; i<XING_HEADER_SIZE; ++i) {
    while(pos >= buf->size)
	{
      buf  = buf->next;

	  //fixed by Hauke Duden
	  //this has to be checked BEFORE accessing buf->pos
	  if(!buf) 	return -1; /* fatal error */

      pos = buf->pos;      
    }
    xing[i] = buf->pnt[pos];
    ++pos;
  }

  /* check first bytes for Xing header */
  mp->vbr_header = GetVbrTag(&pTagData,xing);
  if (mp->vbr_header) {
    mp->num_frames=pTagData.frames;
    mp->enc_delay=pTagData.enc_delay;
    mp->enc_padding=pTagData.enc_padding;

    //fprintf(stderr,"\rmpglib: delays: %i %i \n",mp->enc_delay,mp->enc_padding);
    // fprintf(stderr,"\rmpglib: Xing VBR header dectected.  MP3 file has %i frames\n", pTagData.frames);
    return pTagData.headersize;
  }
  return 0;
}







int sync_buffer(PMPSTR mp,int free_match) 
{
	/* traverse mp structure without modifing pointers, looking
	* for a frame valid header.
	* if free_format, valid header must also have the same
	* samplerate.   
	* return number of bytes in mp, before the header
	* return -1 if header is not found
	*/
	unsigned int b[4]={0,0,0,0};
	int i,h,pos;
	struct buf *buf=mp->tail;

	pos = buf->pos;
	for (i=0; i<mp->bsize; i++)
	{
		/* get 4 bytes */

		b[0]=b[1]; b[1]=b[2]; b[2]=b[3];
		while(pos >= buf->size)
		{
			buf  = buf->next;
			//fixed by Hauke Duden
			//this has to be checked BEFORE accessing buf->pos
			if(!buf)
			{
				return -1;
				/* not enough data to read 4 bytes */
			}
			pos = buf->pos;
		}
		b[3] = buf->pnt[pos];
		++pos;

		if (i>=3)
		{
			struct frame *fr = &mp->fr;
			unsigned long head;

			head = b[0];
			head <<= 8;
			head |= b[1];
			head <<= 8;
			head |= b[2];
			head <<= 8;
			head |= b[3];
			h = head_check(head,fr->lay);

			if (h && free_match)
			{
				/* just to be even more thorough, match the sample rate */
				int mode,stereo,sampling_frequency,mpeg25,lsf;

				if( head & (1<<20) )
				{
					lsf = (head & (1<<19)) ? 0x0 : 0x1;
					mpeg25 = 0;
				}
				else
				{
					lsf = 1;
					mpeg25 = 1;
				}

				mode      = ((head>>6)&0x3);
				stereo    = (mode == MPG_MD_MONO) ? 1 : 2;

				if(mpeg25)
					sampling_frequency = 6 + ((head>>10)&0x3);
				else
					sampling_frequency = ((head>>10)&0x3) + (lsf*3);
				h = ((stereo==fr->stereo) && (lsf==fr->lsf) && (mpeg25==fr->mpeg25) && 
				 (sampling_frequency == fr->sampling_frequency));
			}

			if (h)
				return i-3;
		}
	}
	
	return -1;
}





int decodeMP3( PMPSTR mp,unsigned char *in,int isize,char *out,
		int osize,int *done)
{
	int i,iret,bits,bytes;

	if(osize < 4608)
	{
		//fprintf(stderr,"To less out space\n");
		return MP3_ERR;
	}

	if(in!=NULL)
	{
		if(addbuf(mp,in,isize) == NULL)
			return MP3_ERR;
	}


	/* First decode header */
	if(!mp->header_parsed)
	{
	    if (mp->fsizeold==-1 || mp->sync_bitstream)
		{
	        int vbrbytes;

			mp->sync_bitstream=0;

	        /* This is the very first call.   sync with anything */
			/* bytes= number of bytes before header */
	        bytes=sync_buffer(mp,0); 

	        /* now look for Xing VBR header */
			if (mp->bsize >= bytes+XING_HEADER_SIZE )
			{
				/* vbrbytes = number of bytes in entire vbr header */
				vbrbytes=check_vbr_header(mp,bytes);
			}
			else
			{
				/* not enough data to look for Xing header */
				
				//changed for DecMPA
				//since DecMPA only passes in full frames and there is
				//not enough data for a xing header, there is no Xing header.
				if(mp->bsize==0)
					return MP3_NEED_MORE;	//no data at all, need next frame
				else
				{
					//frame too small for xing header => no xing header
					mp->vbr_header=0;
					vbrbytes=0;
				}
				//return MP3_NEED_MORE;			

			}

			if (mp->vbr_header)
			{
				/* do we have enough data to parse entire Xing header? */
				if (bytes+vbrbytes > mp->bsize)
					return MP3_NEED_MORE;
		    
				/* read in Xing header.  Buffer data in case it
				 * is used by a non zero main_data_begin for the next
				 * frame, but otherwise dont decode Xing header */
				/*fprintf(stderr,"found xing header, skipping %i bytes\n",vbrbytes+bytes);*/
				for (i=0; i<vbrbytes+bytes; ++i)
					read_buf_byte(mp);

				/* now we need to find another syncword */
				/* just return and make user send in more data */
				return MP3_NEED_MORE;
			}
		}
		else
		{
	        /* match channels, samplerate, etc, when syncing */
			bytes=sync_buffer(mp,1);
	    }

	    if (bytes<0)
			return MP3_NEED_MORE;
	    if (bytes>0)
		{
			/* there were some extra bytes in front of header.
			 * bitstream problem, but we are now resynced 
			 * should try to buffer previous data in case new
			 * frame has nonzero main_data_begin, but we need
			 * to make sure we do not overflow buffer
			 */
			int size;
		
			//fprintf(stderr,"bitstream problem: resyncing...\n");
			mp->old_free_format=0;
			mp->sync_bitstream=1;
		
			/* skip some bytes, buffer the rest */
			size = (int) (wordpointer - (mp->bsspace[mp->bsnum]+512));
		
			if (size > MAXFRAMESIZE)
			{
				/* wordpointer buffer is trashed.  probably cant recover, but try anyway */
				//fprintf(stderr,"mpglib: wordpointer trashed.  size=%i (%i)  bytes=%i \n",
					//size,MAXFRAMESIZE,bytes);		  
			    size=0;
				wordpointer = mp->bsspace[mp->bsnum]+512;
			}
		
			/* buffer contains 'size' data right now 
			we want to add 'bytes' worth of data, but do not 
			exceed MAXFRAMESIZE, so we through away 'i' bytes */
			i = (size+bytes)-MAXFRAMESIZE;
			for (; i>0; --i)
			{
				--bytes;
				read_buf_byte(mp);
			}
		
			copy_mp(mp,bytes,wordpointer);
			mp->fsizeold += bytes;
	    }
	    
	    read_head(mp);
	    decode_header(&mp->fr,mp->header);
	    mp->header_parsed=1;
	    mp->framesize = mp->fr.framesize;
	    mp->free_format = (mp->framesize==0);
	    
	    if(mp->fr.lsf)
			mp->ssize = (mp->fr.stereo == 1) ? 9 : 17;
	    else
			mp->ssize = (mp->fr.stereo == 1) ? 17 : 32;
	    if (mp->fr.error_protection) 
			mp->ssize += 2;
	    
	    mp->bsnum = 1-mp->bsnum; /* toggle buffer */
	    wordpointer = mp->bsspace[mp->bsnum] + 512;
	    bitindex = 0;
	    
	    /* for very first header, never parse rest of data */
		//Hauke Duden: why? header_parsed is 1 so continuing here is the same
		//as returning and then being called again with no new data (or not
		//enough new data)
		//=> removed
	    //if (mp->fsizeold==-1)
			//return MP3_NEED_MORE;
		
	}
	
	/* now decode side information */
	if (!mp->side_parsed)
	{
		/* Layer 3 only */
		if (mp->fr.lay==3)
		{
			if (mp->bsize < mp->ssize) 
				return MP3_NEED_MORE;

			copy_mp(mp,mp->ssize,wordpointer);

			if(mp->fr.error_protection)
				getbits(16);
			bits=do_layer3_sideinfo(&mp->fr);
			
			/* bits = actual number of bits needed to parse this frame */
			/* can be negative, if all bits needed are in the reservoir */
			if (bits<0)
				bits=0;

			/* read just as many bytes as necessary before decoding */
			mp->dsize = (bits+7)/8;

			/* this will force mpglib to read entire frame before decoding */
			/* mp->dsize= mp->framesize - mp->ssize;*/
		}
		else
		{
			/* Layers 1 and 2 */

			/* check if there is enough input data */
			if(mp->fr.framesize > mp->bsize)
				return MP3_NEED_MORE;

			/* takes care that the right amount of data is copied into wordpointer */
			mp->dsize=mp->fr.framesize;
			mp->ssize=0;
		}

		mp->side_parsed=1;
	}

	/* now decode main data */
	iret=MP3_NEED_MORE;
	if (!mp->data_parsed )
	{
		if(mp->dsize > mp->bsize)
			return MP3_NEED_MORE;

		copy_mp(mp,mp->dsize,wordpointer);

		*done = 0;

		//do_layer3(&mp->fr,(unsigned char *) out,done);
		switch (mp->fr.lay)
		{
#ifdef USE_LAYER_1
			case 1:
				if(mp->fr.error_protection)
					getbits(16);

				do_layer1(mp,(unsigned char *) out,done);
			break;
#endif
#ifdef USE_LAYER_2
			case 2:
				if(mp->fr.error_protection)
					getbits(16);

				do_layer2(mp,(unsigned char *) out,done);
			break;
#endif
			case 3:
				do_layer3(mp,(unsigned char *) out,done);
			break;
			default:
				//fprintf(stderr,"invalid layer %d\n",mp->fr.lay);
				break;
		}

		wordpointer = mp->bsspace[mp->bsnum] + 512 + mp->ssize + mp->dsize;

		mp->data_parsed=1;
		iret=MP3_OK;
	}


	/* remaining bits are ancillary data, or reservoir for next frame 
	 * If free format, scan stream looking for next frame to determine
	 * mp->framesize */
	if (mp->free_format)
	{
		if (mp->old_free_format)
		{
			/* free format.  bitrate must not vary */
			mp->framesize=mp->fsizeold_nopadding + (mp->fr.padding);
		}
		else
		{
			bytes=sync_buffer(mp,1);
			if (bytes<0)
				return iret;
			mp->framesize = bytes + mp->ssize+mp->dsize;
			mp->fsizeold_nopadding= mp->framesize - mp->fr.padding;
			/*
			fprintf(stderr,"freeformat bitstream:  estimated bitrate=%ikbs  \n",
				8*(4+mp->framesize)*freqs[mp->fr.sampling_frequency]/
				(1000*576*(2-mp->fr.lsf)));
			*/
		}
	}

	/* buffer the ancillary data and reservoir for next frame */
	bytes = mp->framesize-(mp->ssize+mp->dsize);
	if (bytes > mp->bsize)
		return iret;

	if (bytes>0)
	{
		int size;
		copy_mp(mp,bytes,wordpointer);
		wordpointer += bytes;

		size = (int) (wordpointer - (mp->bsspace[mp->bsnum]+512));
		if (size > MAXFRAMESIZE)
		{
			//fprintf(stderr,"fatal error.  MAXFRAMESIZE not large enough.\n");
		}
	}

	/* the above frame is completey parsed.  start looking for next frame */
	mp->fsizeold = mp->framesize;
	mp->old_free_format = mp->free_format;
	mp->framesize =0;
	mp->header_parsed=0;
	mp->side_parsed=0;
	mp->data_parsed=0;

	return iret;
}

	

