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

// list of tags: https://exiftool.org/TagNames/JPEG.html


int main(int argc,char*argv[]){
  FILE*fi;
  int c,oldc;
  int ischunk=0;
  int isdata=0;
  int chunklen=0;
  int chunkpos=0;
  int readoffs=0;
  fi=stdin;
  ischunk=0;
  while(!feof(fi)){
    oldc=c;
    c=fgetc(fi);readoffs++;
//    printf("%02x ",c);
    if(!isdata)
    if(!ischunk)if(oldc==0xff){
      ischunk=1;
      chunkpos=0;
      printf("\nChunk: %02x%02x  offs: %6d ",oldc,c,readoffs-2);
      if(c==0xc0){printf(" [SOF]  ");ischunk=0;chunkpos=0;}else
      if(c==0xc4){printf(" [HUFFT]");ischunk=0;chunkpos=0;}else
      if(c==0xd8){printf(" [START]");ischunk=0;chunkpos=0;}else
      if(c==0xdb){printf(" [QUANT]");ischunk=0;chunkpos=0;}else
      if(c==0xe0){printf(" [APP0] ");ischunk=0;chunkpos=0;}else
//      if(c==0xe1){printf(" [EXIF] ");ischunk=0;chunkpos=0;}else
      if(c==0xe1){printf(" [APP1] ");ischunk=0;chunkpos=0;}else
      if(c==0xe2){printf(" [APP2] ");ischunk=0;chunkpos=0;}else
      if(c==0xe3){printf(" [APP3] ");ischunk=0;chunkpos=0;}else
      if(c==0xe4){printf(" [APP4] ");ischunk=0;chunkpos=0;}else
      if(c==0xe5){printf(" [APP5] ");ischunk=0;chunkpos=0;}else
      if(c==0xe6){printf(" [APP6] ");ischunk=0;chunkpos=0;}else
      if(c==0xe7){printf(" [APP7] ");ischunk=0;chunkpos=0;}else
      if(c==0xe8){printf(" [APP8] ");ischunk=0;chunkpos=0;}else
      if(c==0xe9){printf(" [APP9] ");ischunk=0;chunkpos=0;}else
      if(c==0xea){printf(" [APP10]");ischunk=0;chunkpos=0;}else
      if(c==0xeb){printf(" [APP11]");ischunk=0;chunkpos=0;}else
      if(c==0xec){printf(" [APP12]");ischunk=0;chunkpos=0;}else
      if(c==0xed){printf(" [APP13]");ischunk=0;chunkpos=0;}else
      if(c==0xee){printf(" [APP14]");ischunk=0;chunkpos=0;}else
      if(c==0xef){printf(" [APP15]");ischunk=0;chunkpos=0;}else
      if(c==0xda){printf(" [data] ");isdata=1;}else
      if(c==0xfe){printf(" [COMMT]");ischunk=0;chunkpos=0;}else
      if(c==0x00){printf("        ");ischunk=0;chunkpos=0;}else
      {printf(" [?%02x%02x]",oldc,c);ischunk=0;chunkpos=0;}

      continue;
    }
    if(isdata){
      if(oldc==0xff)if(c==0xd9){
        printf("\nChunk: %02x%02x  offs: %6d  [END]   len=%d\n",oldc,c,chunkpos,readoffs-2);ischunk=0;isdata=0;continue;}
    }
    if(feof(fi))break;

//    if(isdata){}//printf(".%02x",c);
//    else if(!ischunk){if(chunkpos>2)printf("_%02x",c);}
//    else {}// printf(" %02x",c);

    chunkpos++;
    if(chunkpos==2){
      chunklen=(oldc<<8)+c;
      printf(" len:%d",chunklen);
    }

    if(ischunk)if(chunklen==chunkpos){
      ischunk=0;
    }

  }
  printf("\n");
  return 0;
}