/*
  * Copyright (c) 2007 Michael Niedermayer
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 
 #include <stdio.h>

 #include <stdlib.h>

 #include <inttypes.h>
 

 static uint32_t state;
 static uint32_t ran(void){
     return state= state*1664525+1013904223;
 }
 

 int main(int argc, char** argv)
 {

     FILE *f;
     int count, maxburst, length;
 

     if (argc < 5){
         printf("USAGE: trasher <filename> <count> <maxburst> <seed>\n");

         return 1;
     }
 
     f= fopen(argv[1], "rb+");
     if (!f){
         perror(argv[1]);
         return 2;
     }
     count= atoi(argv[2]);
     maxburst= atoi(argv[3]);

     state= atoi(argv[4]);

 
     fseek(f, 0, SEEK_END);
     length= ftell(f);
     fseek(f, 0, SEEK_SET);
 
     while(count--){

         int burst= 1 + ran() * (uint64_t) (abs(maxburst)-1) / UINT32_MAX;
         int pos= ran() * (uint64_t) length / UINT32_MAX;

         fseek(f, pos, SEEK_SET);
 
         if(maxburst<0) burst= -maxburst;
 
         if(pos + burst > length)
             continue;
 
         while(burst--){

             int val= ran() * 256ULL / UINT32_MAX;

 
             if(maxburst<0) val=0;
 
             fwrite(&val, 1, 1, f);
         }
     }
 
     return 0;
 }