xmodem.c

基于arm7s3c2410开发板的bootloader的设计与实现源代码 采用汇编语言和C语言编写

/*
 * vivi/deriver/serialxmodem.c:
 *     - an implementation of the xmodem protocol from the spec.
 *
 * Based on bootldr/xmodem.c (C) 2000 Compaq Computer Coporation.
 *
 * Copyright (C) 2001 MIZI Research, Inc.
 *
 *
 * 1999-01-xx: Edwin Foo <[e-mail]>
 *    - Initial code
 *
 * 2001-10-04: Janghoon Lyu <[e-mail]>
 *    - Modified a little bit.
 *
 * 2002-07-04: Janghoon Lyu <[e-mail]>
 *    - get_param_value() 牢磐其捞胶啊 官差绢辑 捞俊 嘎霸 荐沥.
 */
#include "xmodem.h"
#include "led_api.h"


/* global error variable */
char *xmodem_errtxt = NULL;
int get_byte_err = 0;
U8 volatile receive_buffer[BLOCK_SIZE];
long download_addr = 0x8000;
/* prototypes of helper functions */
int get_record(void);
U8 get_byte(void);

enum
{
	SAC_SEND_NAK = 0,
	SAC_SENT_NAK = 1,
	SAC_PAST_START_NAK = 2
};

static volatile int seen_a_char = SAC_SEND_NAK;

static int one_nak = 0;
static unsigned long xmodem_timeout = GET_BYTE_TIMEOUT;

char debugbuf[4096];
int db_idx = 0;
#if 0
void bufputs(char *s)
{
	int len = my_strlen(s) + 1;

	if (len + db_idx > sizeof(debugbuf))
		len = sizeof(debugbuf) - db_idx;

	if (len) {
		my_memcpy(&debugbuf[db_idx], s, len);
		db_idx += len;
	}
}

void reset_debugbuf(void)
{
	my_memset(debugbuf, 0x2a, sizeof(debugbuf));
	db_idx = 0;
}

#endif

void delay()
{
	int j;
	for (j = 0; j < 20000000; j++)
		;
}

U32 xmodem_receive(void)
{
	char ochr;
	int r = 0, rx_block_num = 0, error_count = 0;
	U32 foffset = 0;
	int i;
	int ret;
	char nak = NAK;
	int j = 50000;
	xmodem_errtxt = NULL;
	seen_a_char = 0;

#if 0
	one_nak = get_param_value("xmodem_one_nak", &ret);
	if (ret) one_nak = 0;

	xmodem_timeout = get_param_value("xmodem_initial_timeout", &ret);
	if (ret) xmodem_timeout = GET_BYTE_TIMEOUT;
#endif
	delay();
	uart_putchar(UART0_BASE, nak);
	
	rx_block_num = 1;

	/* times to retry */
	error_count = RETRIES;

	do {
		/* when local block number equals to the block number in the packet,
			store the data into the memory which download_addr points*/
		if ((r = get_record()) == (rx_block_num & 255)) {
			error_count = RETRIES;
			for (i = 0; i <BLOCK_SIZE; i++)
				*(U8 *)(download_addr+foffset+i) = receive_buffer[i];
			xmodem_errtxt = "RX PACKET";
			rx_block_num++;
			ochr = ACK;
			foffset += BLOCK_SIZE;
		} else {
			switch (r) {
			case -1: /* TIMEOUT */
				xmodem_errtxt = "TIMEOUT";
				ochr = NAK;
				break;
			case -2: /* Bad block */
				xmodem_errtxt = "BAD BLOCK#";
				/* eat teh rest of the block */
#if 0
				get_byte_err = 0;
				while (get_byte_err != -1) get_byte();
#endif
				ochr = NAK;
				break;
			case -3: /* Bad checksum */
				xmodem_errtxt = "BAD CHKSUM";
				ochr = NAK;
				break;
			case -4: /* End of file */
				xmodem_errtxt = "DONE";
				ochr = ACK;
				break;
			case -5: /* Cancel */
				xmodem_errtxt = "ABORTED";
				ochr = ACK;
				break;
			default: /* Block out of sequence */
				xmodem_errtxt = "WRONG BLK";
				ochr = NAK;
			}
			error_count--;
		}
		/**/
		uart_putchar(UART0_BASE, ochr);
	} while ((r > -3) && error_count);

	if ((!error_count) || (r != -4)) {
		foffset = 0;	/* indicate failure to caller */
		/*printk("x-modem error: %s\n", xmodem_errtxt); */
	}

	return foffset;
}

/*
 * Read a record in the XMODEM protocol, return the block number
 * (0-255) if successful, or one of the following return codes:
 * 	-1 = Bad byte
 * 	-2 = Bad block number
 * 	-3 = Bad block checksum
 * 	-4 = End of file
 * 	-5 = Canceled by remote
 */
int get_record(void)
{
	char c; 
	int block_num = 0;
	int i;

	U32 check_sum;

	/* clear the buffer */
	for (i = 0; i < BLOCK_SIZE; i++)
		receive_buffer[i] = 0x00;

	check_sum = 0;

	/* initialize i to -2,when begin to transfer,the first byte
	   will be store into blcok_num,and after plused one,the next
	   byte will be treated as a negated section */
	i = -2;
	uart_getchar( UART0_BASE, &c);

	switch (c) 
	{
		case SOH:	/* Receive packet */
			for (;;) 
			{
				uart_getchar( UART0_BASE, &c);

				switch (i) 
				{
					case -2: 
						block_num = c;
						break;
				
					case -1:
#if 0
#ifdef CHECK_NEGATED_SECTNUM
				if (c != (-block_num -1))
					return -2;
#endif
#endif
						break;
					case BLOCK_SIZE:
					/* check if reveived data is correct,
				   	when correct,block num is returned,
				  	 else -3 is returned */
						if ((check_sum & 0xff) != c)
							return -3;
						else
							return block_num;
						break;
					
					default:
					/* save data to buffer,and accumulate to check_sum */
						receive_buffer[i] = c;
						check_sum += c;
				}
				i++;
			}
	case EOT:	/* end of file encountered */
		return -4;
	case CAN:	/* cancel protocol */
		return -5;
	default:
		return -5;
	}
}