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

#define ARRAYSIZE(x) (sizeof(x) / sizeof(x[0]))
#define TRACK_SIZE 5325

void write_data(FILE *fp, uint8_t *buf, int len) {
   int i;
   uint8_t zero = 0;

   for (i = 0; i < len; i += 2) {
      fwrite(&buf[i+1], 1, 1, fp); 
      fwrite(&buf[i], 1, 1, fp); 
      fwrite(&zero, 1, 1, fp);
   }
}

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 zeros[1000];
   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;
   struct {
      int count;
      uint8_t value;
   } gaps[] = { {60, 0x4e}, {14, 0x00}, {21, 0x00}, {23, 0x00}, {15, 0x00}};
   struct stat data_stat;
   int head, cyl, n, sector;
   int start_bytes;

   memset(zeros, 0, sizeof(zeros));
   data_fd = open("convert.ext", O_RDONLY, 0666);
   if (data_fd < 1) {
      fprintf(stderr, "convert.ext open failed\n");
      exit(1);
   }
   rc = fstat(data_fd, &data_stat);
   if (rc < 0) {
      fprintf(stderr, "convert.ext fstat failed\n");
      exit(1);
   }
   type = 0;
   for (i = 1; i < ARRAYSIZE(cyls); i++) { 
      if (data_stat.st_size == cyls[i] * heads[i] * 16 * 512) {
         type = i;
      }
   }
   if (type == 0) {
      fprintf(stderr, "no matching disk type for file size %d\n", data_stat.st_size);
      exit(1);
   }

   metadata_fd = open("convert.ext.metadata", O_RDONLY, 0666);
   if (metadata_fd < 1) {
      fprintf(stderr, "convert.ext.metadata open failed\n");
      exit(1);
   }
   fwrite(&type, 1, 1, stdout);

   for (cyl = 0; cyl < cyls[type]; cyl++) {
      for (head = 0; head < heads[type]; head++) {
	 start_bytes = ftell(stdout);
	 for (n = 0; n < gaps[0].count/2; n++) {
	    fwrite(&gaps[0].value, 1, 1, stdout);
	    fwrite(&gaps[0].value, 1, 1, stdout);
	    fwrite(zeros, 1, 1, stdout);
	 }
	 for (sector = 0; sector < 16; sector++) {
	    for (n = 0; n < gaps[1].count/2; n++) {
	       fwrite(&gaps[1].value, 1, 1, stdout);
	       fwrite(&gaps[1].value, 1, 1, stdout);
	       fwrite(zeros, 1, 1, stdout);
	    }
	    buf[0] = 0x41;
	    buf[1] = 0xa1;
	    buf[2] = 0x01;
	    buf[3] = cyl;
	    buf[4] = cyl >> 8;
	    buf[5] = 0;
	    buf[6] = sector;
	    buf[7] = head;
	    buf[8] = 0;
	    buf[9] = 0xef;
	    buf[10] = 0xbe;
	    buf[11] = 0x02;
	    fwrite(buf, 12, 1, stdout);
	    for (n = 0; n < gaps[2].count/2; n++) {
	       fwrite(&gaps[2].value, 1, 1, stdout);
	       fwrite(&gaps[2].value, 1, 1, stdout);
	       fwrite(zeros, 1, 1, stdout);
	    }
	    buf[0] = 0x43;
	    buf[1] = 0xa1;
	    buf[2] = 0x01;
	    fwrite(buf, 3, 1, stdout);
	    read(metadata_fd, buf, 24);
	    write_data(stdout, buf, 24);
	    buf[0] = 0xef;
	    buf[1] = 0xbe;
	    buf[2] = 0x02;
	    fwrite(buf, 3, 1, stdout);
	    for (n = 0; n < gaps[3].count/2; n++) {
	       fwrite(&gaps[3].value, 1, 1, stdout);
	       fwrite(&gaps[3].value, 1, 1, stdout);
	       fwrite(zeros, 1, 1, stdout);
	    }
	    buf[0] = 0x43;
	    buf[1] = 0xa1;
	    buf[2] = 0x01;
	    fwrite(buf, 3, 1, stdout);
	    read(data_fd, buf, 512);
	    write_data(stdout, buf, 512);
	    buf[0] = 0xef;
	    buf[1] = 0xbe;
	    buf[2] = 0x02;
	    fwrite(buf, 3, 1, stdout);
	    for (n = 0; n < gaps[4].count/2; n++) {
	       fwrite(&gaps[4].value, 1, 1, stdout);
	       fwrite(&gaps[4].value, 1, 1, stdout);
	       fwrite(zeros, 1, 1, stdout);
	    }
	 }
	 fwrite(zeros, 5325*3 - (ftell(stdout) - start_bytes), 1, stdout);
      }
   }
   close(data_fd);
   close(metadata_fd);
}