/********************************************************************************************
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* File: xmodem.c
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* Version: 1.0.0
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* Copyright: 2011 (c) Guo Wenxue <guowenxue@gmail.com>
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* Description: Xmodem protocal used to download the second stage bootloader(launcher)
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* ChangeLog: 1, Release initial version on "Tue Jul 12 16:43:18 CST 2011"
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*
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*******************************************************************************************/
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#include "common.h"
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#define XMODEM_SOH 0x01 /*Start Of Header, standard Xmodem */
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#define XMODEM_STX 0x02 /*1K-Modem start Xmodem */
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#define XMODEM_EOT 0x04 /*End Of Transmission */
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#define XMODEM_ACK 0x06
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#define XMODEM_NAK 0x15
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#define XMODEM_CAN 0x18 /*Stop transmission */
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#define XMODEM_EOF 0x1a /*CTRL+Z EOF */
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#define XMODEM_BLOCK_SIZE 128
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static int xmodem_wait(void)
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{
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long cnt = 0;
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while (!serial_tstc())
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{
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if (++cnt >= 20000000)
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{
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cnt = 0;
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serial_putc(XMODEM_NAK);
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}
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}
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return 0;
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}
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static int xmodem_read_block(unsigned char block_number, char *buf)
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{
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unsigned char c, block_num, check_sum;
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int i;
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block_num = serial_getc();
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if (block_num != block_number)
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return -1;
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block_num ^= serial_getc();
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if (block_num != 0xff)
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return -1;
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check_sum = 0;
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for (i = 0; i < XMODEM_BLOCK_SIZE; i++)
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{
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c = serial_getc();
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*(buf++) = c;
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check_sum += c;
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}
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check_sum ^= serial_getc();
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if (check_sum)
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return -1;
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return i;
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}
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long xmodem_recv(char *buf)
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{
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int r, receiving = 0;
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long size = 0;
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unsigned char c, block_number = 1;
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while (1)
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{
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if (!receiving)
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xmodem_wait();
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c = serial_getc();
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switch (c)
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{
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case XMODEM_EOT:
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serial_putc(XMODEM_ACK);
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/*Remove the CMPEOF */
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long cnt = 0;
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if ((buf[-1] == XMODEM_EOF) && (buf[-2] == XMODEM_EOF) && (buf[-3] == XMODEM_EOF))
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{
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while (size && buf[-cnt - 1] == XMODEM_EOF)
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cnt++;
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}
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size -= cnt;
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goto RECV_OK;
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case XMODEM_CAN:
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return -1;
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case XMODEM_SOH:
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receiving++;
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r = xmodem_read_block(block_number, buf);
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if (r < 0)
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{
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serial_putc(XMODEM_NAK);
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}
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else
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{
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block_number++;
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size += r;
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buf += r;
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serial_putc(XMODEM_ACK);
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}
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break;
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default:
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if (receiving)
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return -1;
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}
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}
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RECV_OK:
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return size;
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}
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