#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define TRACK_SIZE 5325
int main(int argc, char *argv[]) {
   int done = 0;
   int rc;
   uint8_t type = 0;
   int cyls[] = {0, 256, 512, 1172};
   int heads[] = {0, 4, 8, 7};
   uint8_t buf[TRACK_SIZE*3];
   uint8_t metadata[TRACK_SIZE*2];
   int metadata_ndx;
   uint8_t data[TRACK_SIZE*2];
   int data_ndx;
   int ignore;
   int header_count;
   int data_fd, metadata_fd;
   int tracks = 0;
   int i;

   rc = read(STDIN_FILENO, &type, 1);
   if (rc != 1 || type < 1 || type > 3) {
      fprintf(stderr, "Invalid type byte %d\n", type);
      exit(1);
   }
   data_fd = open("convert.ext", O_WRONLY | O_CREAT | O_TRUNC, 0666);
   if (data_fd < 1) {
      fprintf(stderr, "convert.ext open failed\n");
      exit(1);
   }
   metadata_fd = open("convert.ext.metadata", O_WRONLY | O_CREAT | O_TRUNC, 0666);
   if (metadata_fd < 1) {
      fprintf(stderr, "convert.ext.metadata open failed\n");
      exit(1);
   }
   do {
      ignore = 1;
      metadata_ndx = 0;
      data_ndx = 0;
      rc = read(STDIN_FILENO, &buf, TRACK_SIZE*3);
      if (rc == 0) {
         done = 1;
      } else if (rc < 0) {
         fprintf(stderr, "Read error\n");
         exit(1);
      } else if (rc != TRACK_SIZE*3) {
         fprintf(stderr, "Short read %d\n", rc);
         exit(1);
      } else {
         for (i = 0; i < TRACK_SIZE*3; i += 3) {
            if (buf[i+2] == 1) {
               if (buf[i] == 0x41) {
                  ignore = 1;
                  header_count = 0;
               } else if (buf[i] == 0x43) {
                  ignore = 0;
                  header_count++;
               } else {
                  fprintf(stderr, "Bad sector header %x\n", buf[i]);
                  exit(1);
               }
            } else if (buf[i+2] == 2) {
            } else if (buf[i+2] == 0) {
               if (!ignore) {
                  if (header_count == 1) {
                     metadata[metadata_ndx++] = buf[i+1];
                     metadata[metadata_ndx++] = buf[i];
                     if (metadata_ndx % 24 == 0) {
                        ignore = 1;
                     } 
                  } else if (header_count == 2) {
                     data[data_ndx++] = buf[i+1];
                     data[data_ndx++] = buf[i];
                     if (data_ndx % 512 == 0) {
                        ignore = 1;
                     } 
                  }
               }   
            } else {
               fprintf(stderr, "Bad word flag %x %d\n", buf[i+2], i);
               exit(1);
            }
         }
         write(metadata_fd, metadata, metadata_ndx);
         write(data_fd, data, data_ndx);
         tracks++;
      }
   } while (!done); 
   close(data_fd);
   close(metadata_fd);
   printf("Disk is %d cyl %d heads %d tracks. Converted %d tracks\n", 
      cyls[type], heads[type], cyls[type]*heads[type], tracks);
}