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

typedef unsigned long ulg;


/**********************************************************************
 *
 * The following are support routines for inflate.c
 *
 **********************************************************************/

static ulg crc_32_tab[256];

/*
 * Code to compute the CRC-32 table. Borrowed from 
 * gzip-1.0.3/makecrc.c.
 */

static void
makecrc(void)
{
/* Not copyrighted 1990 Mark Adler	*/

  unsigned long c;      /* crc shift register */
  unsigned long e;      /* polynomial exclusive-or pattern */
  int i;                /* counter for all possible eight bit values */
  int k;                /* byte being shifted into crc apparatus */

  /* terms of polynomial defining this crc (except x^32): */
  static const int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

  /* Make exclusive-or pattern from polynomial */
  e = 0;
  for (i = 0; i < sizeof(p)/sizeof(int); i++)
    e |= 1L << (31 - p[i]);

  crc_32_tab[0] = 0;

  for (i = 1; i < 256; i++)
  {
    c = 0;
    for (k = i | 256; k != 1; k >>= 1)
    {
      c = c & 1 ? (c >> 1) ^ e : c >> 1;
      if (k & 1)
        c ^= e;
    }
    crc_32_tab[i] = c;
  }
}

unsigned long comp_crc(unsigned char *p, unsigned long len)
{
	unsigned long crc = 0xFFFFFFFFUL;

	while (len--) {
		crc = crc_32_tab[(crc ^ *p++) & 0xff] ^ (crc >> 8);
	}
	return crc ^ 0xFFFFFFFFUL;
}

unsigned char buffer[0xc0000+10];

/* Original version by Petr Novak for SMC7004ABR rev.2
 * Modified to support SMC7004VWBR PN720.x version by BLFC from Openline ISP 
 */
unsigned char signature[] = { 'B', 'R', 'N', 'A', 'W', 0, 0, 0, 0, 0, };

int main(int argc, char *argv[])
{
	int i;
	unsigned char c;
	unsigned long len = 0;
	unsigned long crc;
	unsigned long *p;
	int fd;

	makecrc();
	memset(buffer, 0xff, sizeof(buffer));

	fd = open(argv[1], O_RDONLY);
	if (fd<0) {
		perror("open PFS (192K) SOHO (576K)");
		exit(1);
	}
	len = read(fd, buffer, 0x30000);
	fprintf(stderr, "Web (PFS) has %lu bytes\n", len);

	memcpy(buffer+len, signature, 10);
	crc = comp_crc(buffer, len+10);
	p = (unsigned long *)(buffer + 0x2fff4);
	p[0] = len + 10;
	p[1] = 0x12345678;
	p[2] = crc;
	close(fd);

	fd = open(argv[2], O_RDONLY);
	if (fd<0) {
		perror("open SOHO (576K)");
		exit(1);
	}
	len = read(fd, buffer+0x30000, 0x90000);
	fprintf(stderr, "Firmware (SOHO) has %lu bytes\n", len);
	crc = comp_crc(buffer+0x30000, len);
	p = (unsigned long *)(buffer + 0xbfff4);
	p[0] = len;
	p[1] = 0x12345678;
	p[2] = crc;
	close(fd);

	memcpy(buffer+0xc0000, signature, 10);

	write(1, buffer, sizeof(buffer));
}