/* epid by Jacob Balazer 

  http://www-personal.umich.edu/~balazer/atsc/

  This program  is licensed free for personal use.
  You may not distribute the source or executable.

*/


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


//i rule

#define BUFFER_SIZE_MB 69
#define EPIDSIZE 20
/* define NULLPACKETS will replace packets with null packets instead of
   just clearing the payload */
#define NULLPACKETS
/* define INVERSE will erase PIDs that you _do not_ specify on 
   the command line */
#define notINVERSE


int main(int argc, char **argv);
void usage(char *argv);



int main(int argc, char **argv)
{
	FILE *input, *output;
	unsigned char *buffer;
	int buffersize, datasize;
	int pid;
	unsigned int zero, one, two, three;
#ifdef DEBUG
	int pidcount[8192];
#endif
	unsigned char epid[8192];
	int packetcount=0, erasecount=0, x, r, argpos, savefiles;
	WIN32_FIND_DATA FileData; 
	HANDLE hSearch;
	char *filepattern, *inputfilename, outputfilename[255];


	if(argc<2)
		usage(argv[0]);

	
	/* check for -s input argument */
	if(argv[1][0] == '-' && argv[1][1] == 's')
	{
		savefiles=1;
		argpos=2;
	}
	else
	{
		savefiles=0;
		argpos=1;
	}

	filepattern = argv[argpos];
	argpos++;
	
	/* set up table of PIDs to erase - 
	    epid[PID] == 0 if PID is not to be erased
		 epid[PID] == 1 if PID is to be erased */
	
	for(x=0; x<8192; x++)
		epid[x]=0;

	for(x=0; (x<(argc-argpos) && x<EPIDSIZE); x++)
	{
		if(1!=sscanf(argv[x+argpos], "%x", &pid))
			usage(argv[0]);
		epid[pid] = 1;
	}

#ifdef DEBUG
	for(x=0; x<8192; x++)
		pidcount[x]=0;
#endif

	  /* allocate memory */
	buffersize = (BUFFER_SIZE_MB*1024*1024/188)*188;
	buffer=malloc(buffersize);
	if(!buffer)
	{
		printf("Error allocating memory\n\n");
		exit(1);
	}
	
	
	/* seach for matching files */
	hSearch = FindFirstFile(filepattern, &FileData); 
	if (hSearch == INVALID_HANDLE_VALUE) 
	{
		printf("No files match \"%s\"\n", filepattern);
		return(0);
	}
	
	
	while (1)  /* one iteration per file */
	{		
		packetcount = 0;
		erasecount = 0;

		  /* open input */
		inputfilename = FileData.cFileName;
		input = fopen(inputfilename, "rb");
		if(!input)
		{
			printf("Error opening file \"%s\" for reading\n\n", inputfilename);
			exit(1);
		}

		  /* open output */
		strcpy(outputfilename, inputfilename);
		strcat(outputfilename, ".out");
		output = fopen(outputfilename, "wb");
		if(!output)
		{
			printf("Error opening file \"%s\" for writing\n\n", outputfilename);
			exit(1);
		}


		/* for each buffersize chunk of input */
		while(!feof(input))
		{
			/* read input */
			datasize = fread(buffer, 1, buffersize, input);
			if(datasize == 0)
				return(0);

			for(x=0; x<datasize; x+=188)  /* for each packet */
			{
				zero = buffer[x];
				one = buffer[x+1];
				two = buffer[x+2]; 
				three = buffer[x+3];
				pid = ((one & 0x1F)<<8) + two;

				/*if(two != 0x21)
				if(one)
					printf("byte %d:  %x %x %x %x %x %x\n", x, zero, one, two, three ,pid, pid2); 
				printf("byte %d: sync: %c pid: %X\n", x, (int)buffer[x], (int)pid); */

#ifdef DEBUG
				pidcount[pid]++;
#endif
				packetcount++;

				if(zero!=0x47)
				{
					printf("Error in %s: missing, bad, or mis-aligned sync\n", inputfilename);
					exit(1);
				}

				/* printf("three:  0x%x\n", three & 0x30); */

#ifndef INVERSE  /* normal */
				if(zero==0x47 && epid[pid]) /* if we're to erase this PID */
#else				  /* inverse */				
				if(zero==0x47 && !epid[pid]) /* if we're to erase this PID */
#endif

				{
#ifndef NULLPACKETS  /* just clear payload */
					/* leave header intact, including PID */
					/* leave adaptation header intact, if it exists */

					if((three & 0x30) == 0x10) /* if packet contains payload only */
					{
						memset(&buffer[x+4], 0x00, 184);  /* clear rest of packet */
						erasecount++;
					}
					else if(three & 0x20)  /* if packet has adaptation header possibly followed by payload */
					{
						/* clear payload after adaptation header */
						int payload_length;
						int adaptation_header_length = buffer[x+5] + 1;  /* I think this is a bug; 5 should be changed to 4. haven't tested */
						
						adaptation_header_length = min(adaptation_header_length, 184);
						  /* in case the length field is corrupted, don't let the
						     length field indicate a length that would go past the
							  end of the 188-byte packet */

						payload_length = 188 - adaptation_header_length - 4;

/*						printf("Adaptation header length: %d\n", adaptation_header_length); */
						
						memset(&buffer[x + 4 + adaptation_header_length], 0x00, payload_length);
						erasecount++;
					}



#else					/* replace with null packet */
					buffer[x+1] = 0x1F;
					buffer[x+2] = 0xFF; 
					buffer[x+3] = 0x10;  /* thanks to Leszek Mazur for pointing out a bug here */
					memset(&buffer[x+4], 0x00, 184);  /* clear rest of packet */
					erasecount++;
#endif					
					
				}

			}

			/* write output */
			r = fwrite(buffer, 1, datasize, output);
			if(r!=datasize)
			{
				printf("Error writing to file \"%s\"\n", outputfilename);
				exit(1);
			}

		}
#ifdef DEBUG
		for(x=0; x<8192; x++)
			if(pidcount[x])
				printf("pid %x: %d\n", x, pidcount[x]); */
#endif

		printf("%s: erased %d of %d packets (%2.1f%%)\n", inputfilename, erasecount, packetcount, ((double)erasecount)/packetcount*100);
		
		fclose(input);
		fclose(output);


		/* replace input file with new output */
		if(!savefiles)
		{
			if(!DeleteFile(inputfilename))
			{
				printf("Error deleting file %s after processing was complete\n", inputfilename);
				exit(1);
			}
			
			if(!MoveFile(outputfilename, inputfilename))
			{
				printf("Error renaming file %s\n", outputfilename);
				exit(1);
			}
		}



		/* find next matching file */
		
		if (!FindNextFile(hSearch, &FileData)) 
		{
			if (GetLastError() == ERROR_NO_MORE_FILES) 
			{ 
				break; /* break out of while() loop */
			} 
			else 
			{ 
				printf("Error reading next file\n");
				return(1);
			} 
		}
	
	
	
	} /* end of per-file while */

	/* close search handle */
	if (!FindClose(hSearch)) 
	{ 
		printf("Couldn't close search handle."); 
		exit(1);
	} 


	return(0);
}


void usage(char *argv)
{
	printf("Usage: %s [-s] <input file/pattern> [0xPID] [0xPID] ...\n", argv);
	printf("  -s: save input files instead of overwriting them\n");
	exit(1);
}