id3tag.c

本程序为ST公司开发的源代码

					p = 0; 	// no saved bytes
					XAR_SeekFile(song_info, n, 0);
					
				}
				res = XAR_ReadFile(song_info, buffer + p, cnt, IO_READ_CACHE); // fill rest of buffer
				
				load_pos = n;
				if(!res)
					return E_READ_FAILURE;
			}
			
			// set string leading byte address
			song_info->strings[song_info->strtop] = 0 ; // to indicate that no characters were added so far
			//song_info->infos[song_info->n_infos].pstring = song_info->strings + song_info->strtop;
			song_info->infos[song_info->n_infos].string_offset = song_info->strtop;	
			
			frID = (buffer[pos - load_pos] << 16) 
				+ (buffer[pos - load_pos + 1] << 8) 
				+ buffer[pos - load_pos + 2];
			if(id32rev!=2)
				frID = (frID << 8) + buffer[pos - load_pos + 3];
			frflags = (buffer[pos - load_pos + 8] << 8) + buffer[pos-load_pos + 9];
			
			processing_switch = ID32_READ_DATA;
			
			switch(id32rev)
			{
				case 2:
					id_frtop = (buffer[pos - load_pos + 3] << 16) 
						+ (buffer[pos - load_pos + 4] << 8) 
						+ buffer[pos - load_pos + 5];
					if(!id_frtop)
					{
					 	processing_switch = ID32_TERMINATE;
					 	break;
					 	
					}
					id_data = pos+6;
					id_frtop += id_data;
					switch(frID)	// revision 2
					{
						case TXT_TAL:
							song_info->infos[song_info->n_infos].info_type = ALBUM_TITLE;
							break;
						case TXT_TT2:
							song_info->infos[song_info->n_infos].info_type = SONG_TITLE;
							break;
						case TXT_TP1:
							song_info->infos[song_info->n_infos].info_type = ARTIST;
							break;
						case TXT_COM:
							if(comment)
							    processing_switch = ID32_FRAME_SKIP;
							else
								song_info->infos[song_info->n_infos].info_type = COMMENT;
							break;
						case TXT_TYE:
							song_info->infos[song_info->n_infos].info_type = YEAR;
							break;
						case TXT_TCO:
							song_info->infos[song_info->n_infos].info_type = GENRE;
							break;
						case TXT_TRK:
							song_info->infos[song_info->n_infos].info_type = TRACK_NO;
							break;
						default:
							processing_switch = ID32_FRAME_SKIP;
							
					}
					break;
				case 3:
				case 4:
					if(id32rev == 3)
						id_frtop = (buffer[pos - load_pos + 4] << 24) 
							+ (buffer[pos - load_pos + 5] << 16) 
							+ (buffer[pos - load_pos + 6] << 8) 
							+ buffer[pos - load_pos + 7];
					else
						id_frtop = (buffer[pos - load_pos + 4] << 21) 
							+ (buffer[pos - load_pos + 5] << 14) 
							+ (buffer[pos - load_pos + 6] << 7) 
							+ buffer[pos - load_pos + 7];
					if(!id_frtop)
					{
					 	processing_switch = ID32_TERMINATE;
					 	break;
					 	
					}
					id_data = pos+10;
					id_frtop += id_data;
					frflags = (buffer[pos - load_pos + 8] << 8) + buffer[pos - load_pos + 9];
					switch(frID)
					{
						case TXT_TALB:
							song_info->infos[song_info->n_infos].info_type = ALBUM_TITLE;
							break;
						case TXT_TIT2:
							song_info->infos[song_info->n_infos].info_type = SONG_TITLE;
							break;
						case TXT_TPE1:
							song_info->infos[song_info->n_infos].info_type = ARTIST;
							break;
						case TXT_COMM:
						    if(comment)
							    processing_switch = ID32_FRAME_SKIP;
							else
							    song_info->infos[song_info->n_infos].info_type = COMMENT;
							break;
						case TXT_TYER:
							song_info->infos[song_info->n_infos].info_type = YEAR;
							break;
						case TXT_TCON:
							song_info->infos[song_info->n_infos].info_type = GENRE;
							break;
						case TXT_TRCK:
							song_info->infos[song_info->n_infos].info_type = TRACK_NO;
							break;
			
						default:
							processing_switch = ID32_FRAME_SKIP;
							break;
					}

					break;
				
				default:
					return E_UNEXPECTED;
					
			}
					
			break;
			
		case ID32_READ_DATA:
			if((song_info->n_infos >= XSONG_INFO_TAGS) || (song_info->strtop >= MAX_STRINGS_SIZE - 2))
			{
				processing_switch = ID32_TERMINATE;
				break;
			}
			

			
			if(id_frtop > v2_length)
			{
				processing_switch = ID32_TERMINATE;
				break;
			}
			
			if(id_frtop > (load_pos + ID3_BUFFER_LENGTH))
			{
				n = pos & (~3);   // new load_pos
				p = wmin(n + ID3_BUFFER_LENGTH, v2_length);
				cnt = p - n;
				if(cnt <= 0)
				{
					processing_switch = ID32_TERMINATE;
					break;
				}								// how many bytes should be prepared in buffer
				if((n-load_pos)<ID3_BUFFER_LENGTH)	// check if data follow continuously
				{
					p = ID3_BUFFER_LENGTH - (n - load_pos);		// count of present bytes to keep
					memcpy(buffer, buffer + (n - load_pos), p );
					cnt -= p  ;
				}
				else	// not continuous jump ( frame is big )
				{
					p = 0; 	// no saved bytes
					XAR_SeekFile(song_info, n, 0);					
				}
				res = XAR_ReadFile(song_info, buffer + p, cnt, IO_READ_CACHE); // fill rest of buffer
				
				load_pos = n;
				if(!res)
					return E_READ_FAILURE;
			}
			
						
			
			// frame data should be in buffer, at least full buffer
			if(id32rev != 2)
			{
				if(id32rev==3)
				{
					cmp_enc = 128+64;
					gr_iden = 0x20;
				}
				else
				{
					cmp_enc = 8+4;
					gr_iden = 0x40;
					if(frflags & 1)		// check length indicator
						id_data += 4;
				}
				
				if(frflags & cmp_enc)	// test encryption & compression
				{
					processing_switch = ID32_FRAME_SKIP;
					goto id32_skipfr;
				}
				
				if(frflags & gr_iden)	// test group identity
				{
					id_data += 1;
				}
				
			
			}
			// start parsing string	
			id32_encoding = (t_TextEncoding)buffer[id_data - load_pos];
			id_data++;
			
      /* All ID3v2 tags are stored as UTF-8 Pascal strings, keep track of the
      ** original encoding type used in the file. */
	        song_info->infos[song_info->n_infos].enc_of_src = id32_encoding;
	        song_info->infos[song_info->n_infos].tag_version = 2;

      if(id_data>=id_frtop)   // ignore frame when contains only encoding byte
      {
          processing_switch = ID32_FRAME_SKIP;
					goto id32_skipfr; 
      }
      
			switch(id32_encoding)
			{
				case TEXT_ENCODING_ISO_8859_1:  /* ISO-8859-1, terminated with 0x00. */
					utf8_conv = 1;
				
asc_loop:		
                    chcnt = cnt0 = 0;			
					p = 1;
					
					if(song_info->infos[song_info->n_infos].info_type != COMMENT)
					    goto id3_unic_skip2;
					
					for(i=0;i<3;i++)
					{
					    if(!buffer[id_data-load_pos+i])
					       cnt0++;
					    
					    if((buffer[id_data-load_pos+i]>96)
					        &&(buffer[id_data-load_pos+i]<123)
					        && ((id_data - load_pos + i) < ID3_BUFFER_LENGTH)
					        && (id_data + i < id_frtop ))
					    {
					        chcnt++;
					    }
					    
					}
			        
			        if(((cnt0==3)||(chcnt == 3))&& (!buffer[id_data-load_pos+i]))
			        {
			            id_data += 4;  // skip language descriptor
			            
			        }
			        
			        chcnt = 0;
			        
					
id3_unic_skip2:					
					
					while(p && ((id_data - load_pos) < ID3_BUFFER_LENGTH) && (id_data < id_frtop))
					{
						word = buffer[id_data - load_pos];
						if(utf8_conv)
						{
							p = write_utf8(song_info,word);
						}
						else
						{
							p = write_byte(song_info,word);		// it is already UTF-8 byte					
						}				
						
						chcnt += p;
						
						id_data++;
					}
			
				 	if(chcnt>0)
				 	{
				 		  /* JS fix 11.9.2007 - first check COMM presence before ptr is increased */
				 	    if(song_info->infos[song_info->n_infos].info_type == COMMENT)
				 	        comment = 1;
				 	    song_info->n_infos++;
				 	}
				 	    
					processing_switch = ID32_FRAME_SKIP; // continue with next frame
					
					break;
					
				case TEXT_ENCODING_UTF_16:   /* UTF-16 encoded Unicode with BOM, terminated with 0x00. */
				case TEXT_ENCODING_UTF_16BE: /* UTF-16BE encoded Unicode without BOM, terminated with 0x00. */
					id_be = 1;
					chcnt = cnt0 = 0;
					p = 1;
					
					if(song_info->infos[song_info->n_infos].info_type != COMMENT)
					    goto id3_unic_skip;
					
					for(i=0;i<3;i++)
					{
					    if(!buffer[id_data-load_pos+i])
					       cnt0++;
					       
					    if((buffer[id_data-load_pos+i]>96)
					        &&(buffer[id_data-load_pos+i]<123)
					        && ((id_data - load_pos + i) < ID3_BUFFER_LENGTH)
					        && (id_data + i < id_frtop ))
					    {
					        chcnt++;
					    }
					    
					}
			        
			        if((chcnt == 3)||(cnt0==3))
			        {
			            chcnt = 0;
			            for(i=0;i<3;i++)
					    {
					        // chcnt += write_byte(song_info,buffer[id_data-load_pos+i]);
					    } 
					    
			            id_data += 5;  // skip language descriptor
			            
			            //if( chcnt < 3)
			            //    goto id3_nodata;
			            
			        }
			        else
			        {
			            chcnt = 0;
			        }

id3_unic_skip:			        
			        
					while(p && ((id_data - load_pos) < ID3_BUFFER_LENGTH) && (id_data < id_frtop))
					{
						word = (buffer[id_data-load_pos]<<8) + buffer[id_data-load_pos+1];
						switch(word)
						{
							//case 0:
							//    id_data += 2;
							//  break;
							    
							case 0xFEFF:
								id_be = 1;
								id_data += 2;
								break;
							case 0xFFFE:
								id_be = 0;
								id_data += 2;
								break;
							default:
								if(!id_be)	// format word to BE
								{
									word = ((word&0xff)<<8) + ((word&0xff00)>>8);
								}
								
								if((id32rev==4)&&((word&0xFC00)==0xD800))
								{
							   	   id_data +=4 ; 	// skip surrogate pair
								}
								else
								{
								   p = write_utf8(song_info,word);
								   chcnt += p;  
								   id_data += 2;
								}
								
						}
					}
					
					if(chcnt>0) 
					{   
						  /* JS fix 11.9.2007 - first check COMM presence before ptr is increased */
					    if(song_info->infos[song_info->n_infos].info_type == COMMENT)
				 	        comment = 1;
					    song_info->n_infos++;
					}
//id3_nodata:					
					processing_switch = ID32_FRAME_SKIP; // continue with next frame
						
					break;

				case TEXT_ENCODING_UTF_8:  /* UTF-8 encoded Unicode, terminated with 0x00. */
					utf8_conv = 0;
					goto asc_loop;			
					
				default:
					processing_switch = ID32_FRAME_SKIP;
					goto id32_skipfr;
			}
			
			
			
id32_skipfr:			
			break;
			
		case ID32_FRAME_SKIP:
			pos = id_frtop;
			if(pos<v2_length)
				processing_switch = ID32_FIND_FRAME;
			else
				processing_switch = ID32_TERMINATE;
				
			break;
		
		case ID32_TERMINATE:
			
			return S_OK;
			
		default:
			return E_UNEXPECTED;
		
	}
			
			
 }		// while
 
}		
	

__inline int hdr_to_frps2(frame_params *fr_ps)
{
    layer *hdr = &fr_ps->header;     /* (or pass in as arg?) */

    fr_ps->stereo = (char) ((hdr->mode == MPG_MD_MONO) ? 1 : 2 );

  return 0; /* all is well */
}


static __inline void decode_packed_info(unsigned int packed_info, layer *hdr)
{
    int b0,b1,b2,b3;

    b0 = packed_info >> 19;

#if SUPPORT_MPEG2_5
    b0 ^= 2;	        /* invert bit so 1 => MPEG 2.5    */
    b0  = b0 & ~(b0>>1); /* clear non-LSF flag if MPEG 2.5 */
#endif

    b1 = (packed_info >> 17) & 3;        // rlay
    b2 = 1 ^ (( packed_info >> 16) & 1); // protection_bit
    b3 = (packed_info >> 12) & 15;       // bitrate_index
#ifdef __BIG_ENDIAN
    ((int *)hdr)[0] = b3 | (b2<<8) | (b1<<16) | (b0<<24);
#else
    ((int *)hdr)[0] = b0 | (b1<<8) | (b2<<16) | (b3<<24);
#endif
    b0 = (packed_info >> 10) & 3;        // sampling_frequency
    b1 = (packed_info >> 9) & 1;         // padding_bit        
    b2 = (packed_info >> 6) & 3;         // mode
    b3 = (packed_info >> 4) & 3;         // mode extension
#ifdef __BIG_ENDIAN