/* movhex -- move load point of .HEX file                                   */
/* copyright 1984  Michael M Rubenstein                                     */

/* NOTE:  This program only changes the address at which the program will   */
/*        be loaded.  The code is not relocated.                            */

/* syntax:  movhex <newaddr> <infile> [<outfile>]                           */

#define PGMNAME         "movhex"
#define BUFSIZE         (16*1024)
#include <stdio.h>

#define MAXLINE         255

unsigned                hexaddr(), atoh();

main(argc, argv)
  int                   argc;
  char                  *argv[];
{
  static unsigned       reloc, addr;
  static FILE           *infile, *outfile;
  char                  line[MAXLINE + 1];

  if (argc < 2 || strcmp(argv[1], "//") == 0)
    error("syntax:  movhex <newaddr> [<infile> [<outfile>]]");

  if (argc < 3)
  {
    infile = stdin;
    outfile = stdout;
  }
  else
  {
    infile = fopen(".hex", "");
    if (copen(infile, argv[2], "r") == NULL)
      error("Cannot open input file.");
    outfile = fopen(".hex", "");
    if (copen(outfile, (argc < 4) ? argv[2] : argv[3], "w") == NULL)
      error("Cannot open output file.");
  }

  if (fgets(line, MAXLINE, infile) != NULL)
  {
    if (strlen(line) < 7)
      error("Invalid HEX file input.");
    reloc = atoh(argv[1]) - hexaddr(line);
    do
    {
      if (strlen(line) >= 7 && strncmp(line, ":00", 3) != 0)
        setaddr(line, hexaddr(line) + reloc);
      setcksum(line);
      fputs(line, outfile);
    } while (fgets(line, MAXLINE, infile) != NULL);
  }
  fclose(infile);
  fclose(outfile);
}

/* get address in hex file line                                             */
unsigned hexaddr(line)
  register char         *line;
{
  static char           a[5] = {0, 0, 0, 0, 0};
  static int            i;

  if (strlen(line) < 7)
    return 0;

  line += 3;
  for (i = 0; i < 4; ++i)
    a[i] = *(line++);
  return atoh(a);
}

/* convert ASCII to HEX                                                     */
unsigned atoh(s)
  register char         *s;
{
  static unsigned       u;

  u = 0;
  while (*s)
    u = (u << 4) + hex(*(s++));
  return u;
}

/* convert an ASCII character to a HEX digit                                */
hex(c)
  register int          c;
{
  if (isdigit(c))
    return c - '0';
  if ((c = toupper(c)) >= 'A' && c <= 'F')
    return c + (10 - 'A');
  error("Invalid HEX digit in string.");
}

/* set an address in a HEX file line to a new value                         */
setaddr(line, a)
  register char         *line;
  register unsigned     a;
{
  static int            i;

  line += 7;
  for (i = 4; i--;)
  {
    *--line = hexdig(a % 16);
    a /= 16;
  }
}

/* convert hex digit to ASCII                                               */
hexdig(d)
  int                   d;
{
  return (d < 10) ? (d + '0') : (d + ('A' - 10));
}

/* set the checksum of the line                                             */
setcksum(l)
  char                  *l;
{
  static int            n;
  static unsigned       chksum;

  n = 16 * hex(*++l);
  n += hex(*++l);
  chksum = -n;
  n += 3;
  while (n--)
  {
    chksum -= 16 * hex(*++l);
    chksum -= hex(*++l);
  }
  *++l = hexdig((chksum >> 4) & 0x0f);
  *++l = hexdig(chksum & 0x0f);
  *++l = '\n';
  *++l = '\0';
}