uucodec.c

bootloader源代码

/*****************************************
 Copyright (c) 2001-2002 
 Sigma Designs, Inc. All Rights Reserved
 Proprietary and Confidential
 *****************************************/

/* This file is part of the boot loader */

/*
 * uucodec.c
 *
 * decode uuencoded stream 
 * 
 * first revision by Ho Lee 11/01/2002
 */

/*
 * uuencode : encode a binary stream using only printing ASCII characters (0x21 - 0x60)
 * 
 * first line : "begin [permission] [filename]"
 * stream : "[length of the line] [stream]"
 *   encode(ch) : ch = (ch == 0) ? 0x60 : ch + 0x20
 *   maximum length = 45 (0x2d + 0x20 = 0x4d = 'M')
 *   stream : 3 bytes => 4 printing bytes 
 *     8 8 8 => 6 6 6 6
 * last line - 1 : 0x60 (length = 0)
 * last line : "end"
 */

#include "uart.h"
#include "util.h"

#define MAX_BUF_LEN 		1024
#define	MAX_RETRIES 		10

#define DECODE(x)			(((x) == 0x60) ? 0 : ((x) - 0x20))
#define ISVALID(x)			((x) > 0x20 && (x) <= 0x60)

// read uuencoded stream from UART and decoded it
// buf : buffer where the decoded stream will be saved to 
// maxlen : maximum length of buffer. 0 for no limit
int serial_uudecode(unsigned char *buf, int maxlen)
{
	int nretry, nlines = 0, nbytes = 0, nloop = 0, len;
   	int i, error = 0, full = 0;
	unsigned char str[MAX_BUF_LEN], *cp, decode[3];

	// look for the begin of the stream
	for (nretry = 0; nretry < MAX_RETRIES; ++nretry) {
		GetRawString(str, MAX_BUF_LEN);
		if (strncmp(str, "begin ", 6) == 0)
			break;
	}

	if (nretry == MAX_RETRIES) {
		PrintUart("\r\n### Timeout ###\r\n", -1);
		return 0;
	}
	
	// decode the stream body
	for (;;) {
		GetRawString(str, MAX_BUF_LEN);

		// print out progress
		// print '.' per 0x40 (64) lines (2880 bytes)
		// print new line per 0x40 '.' : 4096 lines (184320 bytes)
		if ((nlines++ & 0x3f) == 0) {
			if ((nloop++ & 0x3f) == 0) 
				if (nloop != 1)
					PrintUart("\r\n", -1);
			PrintChar('.');
		}

		// decode from printing stream to binary stream
		for (i = 0; str[i] != 0 && str[i] != '\r' && str[i] != '\n'; ++i) {
			if (!ISVALID(str[i])) {
				error = 1;
				break;
			}
			str[i] = DECODE(str[i]);
		}

		if (i == 0 || error)
			break;
		str[i] = 0;

		// if the length of the current line is 0, the next line must have "end" string
		if ((len = str[0]) == 0) {
			GetRawString(str, MAX_BUF_LEN);
			if (strncmp(str, "end", 3) == 0) {
				PrintUart("\r\n", -1);
				return nbytes;
			} else {
				PrintUart("\r\n### No 'end' ###\r\n", -1);
				return -1;
			}
		}

		// decode 4 byte of stream => 3 bytes of original stream
		for (cp = str + 1; len > 0 && !full; len -= 3, cp += 4) {
			decode[0] = (cp[0] << 2) | (cp[1] >> 4);
			decode[1] = (cp[1] << 4) | (cp[2] >> 2);
			decode[2] = (cp[2] << 6) | (cp[3]);

			for (i = 0; i < 3 && i < len; ++i) {
				*buf++ = decode[i];
				if (++nbytes == maxlen) {
					full = 1;
					break;
				}
			}
		}
	}

	PrintUart("\r\n### Invalid data ###\r\n", -1);

	return -1;
}