main.c

完整的Bell实验室的嵌入式文件系统TFS

/* bootblock.c:
 *  This is a single file that contains snippets of code from other portions
 *  of the monitor.  The snippets are duplicated so that no unnecessary
 *  code is included in this bootblock code.
 *  Its purpose is to exist in the HARDWARE-WRITE-PROTECTED boot sector of
 *  system flash (the point into which the CPU jumps when a reset exception
 *  is taken).  It runs a crc32 on the monitors flash space prior to jumping
 *  into it.  If the crc32 passes, then this bootblock code jumps into the
 *  entrypoint of the monitor and the monitor starts up as it normally would;
 *  if the crc32 fails, then an error message is dumped out the serial port
 *  and XMODEM is automatically started.  The XMODEM downloader will wait
 *  forever for a load from the target, and upon completion of that download,
 *  that code is jumped into and assumed to be some temporary version of the
 *  monitor that can execute out of RAM and rebuild the flash.
 *
 *  The sanity test is based on a table that is assumed to be located at the
 *  base of the monitor flash....
 *
 *                  ------------------------------
 *                 | CRC32 Start Address.        |
 *                  ------------------------------
 *                 | CRC32 Size.                 |
 *                  ------------------------------
 *                 | Result of CRC32.            |
 *                  ------------------------------
 *                 | Entrypoint into monitor.    |
 *                  ------------------------------
 *
 *  This code does assume that there are some basic UART functions external
 *  to this file.  The default for this would be to just link in the cpuio.c
 *  that is in the target-specific directory, or create a BOOTBLOCK version
 *  of the cpuio.c that is more compact.
 *
 *  IMPORTANT NOTE:
 *  This is meant to be a small stand-alone block of code that is in a
 *  HARDWARE-WRITE-PROTECTED boot sector of the flash.  This point is 
 *  emphasized because if the sector is not hardware protected, then there is
 *  no point in using this bootblock code.  The monitor has its own software
 *  hooks to do the best job it can to avoid "accidental" overwrites of 
 *  critical flash space and the space owned by TFS has its own CRC32 
 *  corruption detection.  The point of this bootblock is to provide a
 *  fail-safe fallback just in case the monitor itself (not TFS) somehow
 *  becomes corrupted.  This can only be guaranteed if the bootblock is
 *  protected by hardware.
 *
 *  General notice:
 *  This code is part of a boot-monitor package developed as a generic base
 *  platform for embedded system designs.  As such, it is likely to be
 *  distributed to various projects beyond the control of the original
 *  author.  Please notify the author of any enhancements made or bugs found
 *  so that all may benefit from the changes.  In addition, notification back
 *  to the author will allow the new user to pick up changes that may have
 *  been made by other users after this version of the code was distributed.
 *
 *  Author: Ed Sutter
 *  email:  [e-mail]      (home: [e-mail])
 *  phone:  [phone]            (home: 908-889-5161)
 */

#include "stddefs.h"
extern int rputchar();
extern int gotachar();
extern int getchar();

#define XNULL   0
#define XUP 1
#define XDOWN   2

#define SOH 0x01
#define EOT 0x04
#define ACK 0x06
#define NAK 0x15
#define CAN 0x18
#define ESC 0x1b

#define PKTLEN  128

/* prString():
 *  Print the incoming string as is.
 */
void
prString(char *str)
{
    if (str) {
        while(*str)
            rputchar(*str++);
    }
}

/* prHex():
 *  Feed this function a pointer to binary data and it will print it in
 *  ascii hex.
 */
void
prHex(char *prefix, int size,uchar *cp, char *suffix)
{
    uchar   *end;
    static  char *hexdigits = "0123456789abcdef";

    prString(prefix);
    prString("0x");
    end = cp + size;
    while(cp < end) {
        rputchar(hexdigits[(int)((*cp&0xf0)>>4)]);
        rputchar(hexdigits[(int)(*cp&0x0f)]);
        cp++;
    }
    prString(suffix);
}

int
getbytes(char *buf,int cnt)
{
    int i;

    for(i=0;i<cnt;i++) {
        while(!gotachar());
        buf[i] = (char)getchar();
    }
    return(i);
}

/* Xdown():
 *  Called when a transfer from host to target is being made (considered
 *  an download).
 */

int
Xdown(char *binaddress)
{
    volatile long   timeout;
    ushort  word;
    char    c, *pkt;
    int     done, i, pktcnt;
    uchar   csum, xcsum, sno, seq[2], *cp;

    pktcnt = 0;
    sno = 0x01;

    /* Startup synchronization... */
    /* Continuously send NAK until sender responds. */
    while(1) {
        rputchar(NAK);
        timeout = 20000;
        while(!gotachar() && timeout)
            timeout--;
        if (timeout)
            break;
    }

    done = 0;
    while(done == 0) {
        c = (char)getchar();
        switch(c) {
        case SOH:
            getbytes(seq,2);
            getbytes(binaddress,PKTLEN);
            xcsum = (uchar)getchar();
            csum = 0;
            pkt = (char *)binaddress;
            for(i=0;i<PKTLEN;i++)
                csum += *pkt++;
            if (csum != xcsum) {
                rputchar(CAN);
                done = -1;
                break;
            }
            if ((uchar)seq[0] !=  (uchar)sno) {
                rputchar(CAN);
                done = -1;
                break;
            }
            if ((uchar)seq[1] != (uchar) ~sno) {
                rputchar(CAN);
                done = -1;
                break;
            }
            cp = (uchar *)&word;
            binaddress += PKTLEN;
            sno++;
            pktcnt++;
            rputchar(ACK);
            break;
        case CAN:
            done = -1;
            break;
        case EOT:
            rputchar(ACK);
            done = pktcnt*PKTLEN;
            break;
        case ESC:       /* User-invoked abort */
            done = -1;
            break;
        default:
            done = -1;
            break;
        }
    }
    return(done);
}

/* crc32tab[]:
 *  Used for calculating a 32-bit CRC.
 */
unsigned long crc32tab[] = {
    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
};

/* crc32(): */
ulong
crc32(buffer,nbytes)
uchar *buffer;
ulong nbytes;
{
    int temp;
    unsigned long crc_rslt;

    crc_rslt = 0xffffffff;
    while(nbytes) {
        temp = (crc_rslt ^ *buffer++) & 0x000000FFL;
        crc_rslt = ((crc_rslt >> 8) & 0x00FFFFFFL) ^ crc32tab[temp];
        nbytes--;
    }
    return(~crc_rslt);
}

int
main(int argc, char *argv[])
{
    int (*go)();
    char *base;

    base = (char *)0x10000;
    prHex("\r\nBegin xmodem dld at : ",4,(char *)&base,"\r\n");

    while (Xdown((char *)0x10000) < 0)
        prString("xmodem failed, trying again...\r\n");

    /* If we got here, then the xmodem download was successful, so we can
     * jump into the space that was just downloaded and hopefully this
     * will allow the system flash to be rebuilt and sanity restored.
     */

    prString("Transferring control to downloaded app...\r\n");
    go = (int(*)())0x10000;
    go();
    return(0);
}