gdb.c

来自「完整的Bell实验室的嵌入式文件系统TFS」· C语言 代码 · 共 201 行

/* gdb.c:
 *  The code in this file allows a gdb debugger on a host to connect to the
 *  monitor.
 *  Unlike the typical commands in the monitor's command set, the gdb serial
 *  line protocol does not break the line up into whitespace delimited tokens
 *  so the monitor's command interpreter must pass all lines that start with
 *  a '$' to gdb_cmd() and let it do the rest.
 *  NOTE: this is a VERY basic and incomplete implementation of the gdb
 *  interface.  My intent was to simply have the ability to peek and poke
 *  memory with gdb.
 *
 *  I got the information for this out of ESP magazine Sept 1999 issue also
 *  had some discussion with Dave Thomas.
 *
 *  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.
 *
 *  Note1: the majority of this code was edited with 4-space tabs.
 *  Note2: as more and more contributions are accepted, the term "author"
 *         is becoming a mis-representation of credit.
 *
 *  Original author:    Ed Sutter
 *  Email:              [e-mail]
 *  Phone:              908-582-2351
 */
#include "config.h"
#include "genlib.h"
#include "ether.h"
#include "stddefs.h"
#include "cli.h"

/* gdb_m():
 *  GDB memory read command...
 *      mADDR,LEN
 */
int
gdb_m(char *line)
{
    int     len, i;
    uchar   *addr, *lp, csum;
    
    addr = (uchar *)strtol(line+1,(char **)&lp,16);
    len = (int)strtol(lp+1,0,16);
    csum = 0;
    printf("+$");
    for(i=0;i<len;i++,addr++) {
        printf("%02x",*addr);
        csum += *addr;
    }
    printf("#%02x",csum);
    return(0);
}

int
gdb_M(char *line)
{
    printf("gdb_M: %s\n",line);
    return(0);
}

/* gdb_cmd():
 *  First function called out of the monitor's command interpreter.  It
 *  does a basic syntax verification and then passes parameters to the
 *  appropriate handler above.
 *  Incoming syntax is
 *
 *      $ CMD # CSUM (of CMD)
 *
 *  where:
 *      $       is the ascii '$' character (0x24)
 *      #       is the ascii '#' character (0x23)
 *      CMD     is some command line consisting of a command and arguments
 *      CSUM    is the checksum of the characters in CMD
 *
 *  for example:
 *      
 *      $m4015bc,2#5a
 *
 *  Returns...
 *       0 if command is not processed;
 *       1 if command is processed;
 *      -1 if command is processed but has an error;
 *
 *  If this code detects an error, then send an error code back to GDB.
 *  According to the article, there are no defined error codes in GDB so
 *  we will use the following...
 *      E01     indicates a missing '#' at the end of the string.
 *      E02     indicates a bad checksum calculation.
 *      E03     indicates some command processing error.
 */
int
gdb_cmd(uchar *line)
{
    int len, clen, err, i;
    uchar   mycsum, incsum;

    len = strlen(line);

    if (line[len-3] != '#') {
        printf("+$E01#a6");     /* Missing ending '#' */
        return(-1);
    }

    clen = len - 3;
    mycsum = 0;
    for(i=1;i<clen;i++)
        mycsum += line[i];

    incsum = (uchar)strtol(line+len-2,(char **)0,16);
    if (mycsum != incsum) {
        printf("+$E02#a7");     /* Checksum failure */
        return(-1);
    }
    
    err = 0;
    line++;
    switch(*line) {
        case 'm':       /* Memory read */
            err = gdb_m(line);
            break;
        case 'M':       /* Memory write */
            err = gdb_M(line);
            break;
        case 's':       /* step */
        case 'c':       /* continue */
        case '?':       /* last signal */
            printf("+$S05#b8");
            break;
        case 'g':       /* get all registers */
            printf("+$00000000#80");
            break;
        case 'q':       /* */
            printf("+$Text=0;Data=0;Bss=0#04");
            break;
        case 'H':       /* */
            printf("+$OK#9a");
            break;
        default:        /* Unknown... return empty response. */
            printf("+$#00");
            break;
    }
    if (err)
        printf("+$E03#a8");     /* Command processing error */
    return(1);
}

char *GdbHelp[] = {
        "Enter gdb mode",
        "(no options)",
        0,
};

int
Gdb(int argc, char *argv)
{
    int     state;
    char    line[64], *lp, c;

    printf("Entering gdb mode, type ctrl-a to exit.\n");

    state = -1;
    while(1) {
        c = getchar();
        if (c == '$') {
            lp = line;
            state = 0;
        }
        if (c == 0x01)              /* ctrl-a terminates */
            break;
        switch(state) {
            case 0:
                if (c == '#')
                    state = 1;
                *lp++ = c;
                break;
            case 1:
                *lp++ = c;
                state = 2;
                break;
            case 2:
                *lp++ = c;
                *lp = 0;
                state = -1;
                gdb_cmd(line);
                break;
            default:
                break;
        }
#if INCLUDE_ETHERNET
        pollethernet();
#endif
    }
    return(CMD_SUCCESS);
}