/*
 * trx2usr - Convert a TRX firmware image to a U.S. Robotics firmware
 *           image by prepending a 28-byte header.
 *
 * This program was modeled after the usr-hdr.c program from the GPL'ed
 * firmware for the U.S. Robotics Wireless MAXg Router (USR5461). The
 * output file of this program can be uploaded via the web interface
 * of the original U.S. Robotics firmware. Note that this program only
 * works on a little-endian host platform.
 *
 * Copyright (C) 2006 Dick Streefland
 *
 * This is free software, licensed under the terms of the GNU General
 * Public License as published by the Free Software Foundation.
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#define	TRX_MAGIC		"HDR0"

#define	USR_MAGIC		0x30525355	// "USR0"
#define	EPI_VERSION		0x06235d03
#define	COMPAT_ID		1		// USR5461
#define	HARDWARE_REV		1

#define	CRC32_INIT		0xffffffff
#define	CHUNK			(64*1024)

typedef	unsigned char		uint8;
typedef	unsigned short		uint16;
typedef	unsigned int		uint32;

struct	usr_header
{
	uint32	magic;			// "USR0" 
	uint32	len;			// file length without this header 
	uint32	crc32;			// CRC32 of the file without header 
	uint32	version;		// EPI_VERSION
	uint16	compatibility_id;	// COMPAT_ID
	uint16	hardware_revision;	// HARDWARE_REV
	uint32	reserved[2];
};
	
static	const	uint32		crc_32_tab [] =	// CRC polynomial 0xedb88320
{
	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
	0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
	0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
	0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
	0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
	0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
	0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
	0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
	0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
	0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
	0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
	0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
	0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
	0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
	0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
	0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
	0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
	0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
};

static	char	buf[CHUNK];

static	uint32	crc32(uint32 crc, uint8* p, size_t n)
{
	while (n--)
	{
		crc = crc_32_tab[(crc ^ *p++) & 0xff] ^ (crc >> 8);
	}
	return crc;
}

static	int	trx2usr(FILE* trx, FILE* usr)
{
	struct usr_header	hdr;
	size_t			n;

	hdr.magic		= USR_MAGIC;
	hdr.len			= 0;
	hdr.crc32		= CRC32_INIT;
	hdr.version		= EPI_VERSION;
	hdr.compatibility_id	= COMPAT_ID;
	hdr.hardware_revision	= HARDWARE_REV;
	hdr.reserved[0]		= 0;
	hdr.reserved[1]		= 0;
	fwrite(& hdr, sizeof(hdr), 1, usr);
	while ((n = fread(buf, 1, CHUNK, trx)))
	{
		if (hdr.len == 0 && strncmp(buf, TRX_MAGIC, strlen(TRX_MAGIC)) != 0)
		{
			break;
		}
		fwrite(& buf, 1, n, usr);
		hdr.len += n;
		hdr.crc32 = crc32( hdr.crc32, (uint8 *) & buf, n);
	}
	fseek(usr, 0L, SEEK_SET);
	fwrite(& hdr, sizeof(hdr), 1, usr);
	if (n != 0)
	{
		fprintf(stderr, "Input is not a TRX file\n");
		return 1;
	}
	if (hdr.len == 0)
	{
		fprintf(stderr, "Empty input\n");
		return 1;
	}
	if (ferror(trx))
	{
		fprintf(stderr, "Read error\n");
		return 1;
	}
	if (ferror(usr))
	{
		fprintf(stderr, "Write error\n");
		return 1;
	}
	return 0;
}

extern	int	main(int argc, char *argv[])
{
	FILE*	in;
	FILE*	out;
	int	ret;

	if (argc != 3)
	{
		fprintf(stderr, "Usage: trx2usr <trx input> <usr output>\n");
		exit(2);
	}
	in  = fopen(argv[1], "rb");
	if (!in)
	{
		fprintf(stderr, "Cannot open \"%s\": %s\n", argv[1], strerror(errno));
		exit(1);
	}
	out = fopen(argv[2], "wb");
	if (!out)
	{
		fprintf(stderr, "Cannot create \"%s\": %s\n", argv[2], strerror(errno));
		exit(1);
	}
	ret = trx2usr(in, out);
	fclose(in);
	fclose(out);
	if (ret)
	{
		unlink(argv[2]);
	}
	return ret;
}