fget.c

编译命令 cc -o fget fget.c -lcurses 此程序适用于SCO UNIX主机系统

/***************************************************************************
 *                                                                         *
 *     File:          Download Unix File Utility                           *
 *     Function:  This program demostrating download file managment        *
 *                                                                         *
 *     Author:              Long Yun Liang                                 *
 *     Copyright (c) 1,23,1996        All rights reserved                  *
 *                                                                         *
 ***************************************************************************/


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <termio.h>
#include "fget.h"


/**************************************************************************
 *       Revised XMODEM/YMODEM CRC protocol                               *
 *                                                                        *
 *  A data packet is defined as:                                          *
 *       typedef struct {                                                 *
 *               BYTE    soh;            - Start of heading               *
 *               BYTE    seq#;           - sequence number                *
 *               BYTE    not_seq#;       - ~seq#                          *
 *               BYTE    data[128];      - data buffer                    *
 *               BYTE    bc;             - block checksum                 *
 *       } dataPacketRec;                                                 *
 **************************************************************************/

unsigned short Checksum(BYTE *, int);

int main(int argc,char *argv[])
{
    FILE        *fp;
    char        filename[128];

    int         ack_reply;
    int         fd;
    int         retry;
    PacketRec   packet;
    BYTE        *ptr;
    int         n;
    long        i;
    int         buflen;
    unsigned short     bc;
    struct  termio     savetty;
    struct  termio     tdes;

    if (argc<2)  {
	 printf ("Download File Utility  Version 1.00\n");
	 printf ("Copyright (c) Software Engineering 1996-1997.  All rights reserved.\n\n");
	 printf ("Writen by: Long Yunliang . Xi'An China .\n\n");
	 printf ("Usage:  fget TransferFile\n");
	 return 1;
    }

    ioctl (1,TCGETA,&savetty);     /* save original tty */

    ioctl (1,TCGETA,&tdes);
    tdes.c_oflag &= ~OPOST;
    tdes.c_lflag &= ~ECHO;
    tdes.c_lflag &= ~ICANON;
    tdes.c_lflag &= ~XCASE; 
    tdes.c_cc[VMIN]  = 1;
    tdes.c_cc[VTIME] = 1;
    ioctl (1,TCSETA,&tdes);        /* set new tty mode */

    strcpy (filename,argv[1]);
    if ((fd = open(filename, O_RDONLY )) < 0)  {
	printf ("File not found .\n");
	ioctl (1,TCSETA,&savetty);
	return (OPENFAIL);      /* Open file failed */
    } 

    printf ("\x1b[1Y");         /* Support a certain smart phone */    

    packet.soh = SOH;           /* XMODEM transfer file header */
    packet.seq = 0;             /* initialize seqence# */
    for(;;)  {
       ack_reply = getchar();
       if (ack_reply == CRC)   break;
    }
    if ((ack_reply) != CRC)
	return(DISCONN);

    while ( buflen = read(fd, packet.buffer, DATALEN) ) {
	if (buflen < DATALEN)           /* end of file */
	   for (i = buflen;i < DATALEN;i++)
	       packet.buffer[i] = SUB; 
	if (packet.seq == 255)          /* next sequence # */
	    packet.seq = 0;
	else
	    packet.seq++;
	packet.nseq  = ~packet.seq;
	packet.bc[0] = 0x00;
	packet.bc[1] = 0x00;
	bc = Checksum((BYTE *)&packet.buffer, DATALEN);
	packet.bc[0] = (bc >> 8) & 0x00FF;
	packet.bc[1] = bc & 0x00FF;
	retry = MAXRETRY; 
	
	do  {
	} while ((ack_reply = getch()) != -1);

	do  {
	    ptr = (BYTE *)&packet;
	   
		     /* Sending packet */
	    for (n = 0; n < PACKETSIZE; n++, ptr++) {
		 putchar (*ptr); 
	    }

	    for (i = 0;i < 10000;i++)  {
		ack_reply = getchar()&0xff;
		if (ack_reply == CRC) continue;
		if (ack_reply != 0xff) break;
	    }    
		    /* wait for ACK from receiver */
	    switch (ack_reply) {
		case NAK:       /* packet was received incorrectly */
		case 0xff:      /* packet/ACK might get lost */
		    if (--retry == 0)  {         /* DIS-CONNECT */
			ioctl (1,TCSETA,&savetty);
			return(DISCONN);
		    }
		    break;
		case ACK:
		    retry = 0;
		    break;
	    }
	} while (retry > 0);
    }
    close(fd);

    /* Sending EOT */
    retry = MAXRETRY;
    do {
	if (putchar(EOT) == 0) {
	    close(fd);
	    ioctl (1,TCSETA,&savetty);
	    return(DISCONN);
	}
		/* wait for ACK from receiver */
	switch (ack_reply = getchar()&0xff) {
	    case NAK:           /* packet was received incorrectly */
	    case 0xff:          /* packet/ACK might get lost */
		if (--retry == 0)  {         /* DIS-CONNECT */
		    ioctl (1,TCSETA,&savetty);
		    return(DISCONN);
		}
		break;

	    case ACK:
		retry = 0;
		break;
	}
    } while (retry > 0);
  
    ioctl (1,TCSETA,&savetty);
    return(SUCCEED);            /* Send successfully */
}


/***************************************************************************
 *                                                                         *    
 * Function:    Checksum() - compute crc's                                 *
 *                                                                         *
 * crc-16 is based on the polynomial x^16+x^15+x^2+1                       *
 *  The data is assumed to be fed in from least to most significant bit    *
 * crc-ccitt is based on the polynomial x^16+x^12+x^5+1                    *
 *  The data is fed in from most to least significant bit                  *
 * The prescription for determining the mask to use for a given polynomial *
 *    is as follows:                                                       *
 *        1.  Represent the polynomial by a 17-bit number                  *
 *        2.  Assume that the most and least significant bits are 1        *
 *        3.  Place the right 16 bits into an integer                      *
 *        4.  Bit reverse if serial LSB's are sent first                   *
 *                                                                         *
 ***************************************************************************/

/* function declarations */
unsigned short updcrc(unsigned int,int,unsigned int);

unsigned short Checksum(BYTE *buf, int buflen)
{
    /* variables */
    unsigned int crctt;
    int ch;
    int num;

    crctt=0;
    for (num=0;num<buflen;num++)
    {
	ch=*(buf+num);
	crctt=updcrc(crctt,ch,CRC_CCITT);
    }
    return (crctt);
}

/* update crc */
unsigned short updcrc(unsigned int crc,int c,unsigned int mask)
{
    int i;
    c<<=8;
    for(i=0;i<8;i++)
    {
	if((crc ^ c) & 0x8000) crc=(crc<<1)^mask;
	else crc<<=1;
	c<<=1;
    }
    return crc;
}