/*---------------------------------------------------------------------*
 * Copyright (C) 2004 BroadOn Communications Corp.
 *                 
 *  $RCSfile: gdbhandler.c,v $
 *  $Revision: 1.3 $
 *  $Date: 2004/02/17 23:21:53 $
 *
 * Implements the GDB remote serial protocol for the BBPlayer
 * 
 * To do:
 *      - bullet proof mem reads and writes
 *      - bullet proof code against buffer overflows
 *      - implement "G"? (Not needed)
 *      - thread announcement & handling
 *
 *    The following gdb commands are supported:
 *    See gdb/remote.c in gdb source for details
 *
 * command          function                               Return value
 *
 *    Hct...          set thread c = 'c' or 'g'               OK or ENN
 *    g               return the value of the CPU registers   hex data or ENN
 *    Pn=value        set the value of register n to value    OK or ENN
 *
 *    mAA..AA,LLLL    Read LLLL bytes at address AA..AA       hex data or ENN
 *    MAA..AA,LLLL    Write LLLL bytes at address AA.AA       OK or ENN
 *
 *    c               Resume at current address               SNN ( signal NN)
 *    cAA..AA         Continue at address AA..AA              SNN
 *
 *    s               Step one instruction                    SNN
 *    sAA..AA         Step one instruction from AA..AA        SNN
 *
 *    k               kill
 *       
 *    z0,AA..AA,LLLL  Remove(z0)/insert(z1) memory breakpoint 
 *    Z0,AA..AA,LLLL  at address AA..AA of size LLLL          OK or ENN
 * 
 *    Tn              Checks if thread n is still alive       OK or ENN
 *
 *    ?               What was the last sigval ?              SNN (signal NN)
 *
 * Query
 *    qC
 *
 *    qfThreadInfo
 *    qsThreadInfo
 *    qThreadExtraInfo
 *
 *    qSymbol
 *
 * All commands and responses are sent with a packet which includes a
 * checksum.  A packet consists of
 *
 * $<packet info>#<checksum>.
 *
 * where
 * <packet info> :: <characters representing the command or response>
 * <checksum>    :: < two hex digits computed as modulo 256 sum of <packetinfo>>
 *
 * When a packet is received, it is first acknowledged with either '+' or '-'.
 * '+' indicates a successful transfer.  '-' indicates a failed transfer.
 *
 * Example:
 *
 * Host:                  Reply:
 * $m0,10#2a               +$00010203040506070809101112131415#42
 *
 *---------------------------------------------------------------------*/

/* Program tested with GDB 6.0 - compiled with linux as host, 
   mips-linux as target */

#include "ultragdb.h"
#include "os_bb.h"

extern char hexchars[];

/* These variable are used by the gdbIO thread when communicating with GDB */
static char  __gdbInBuffer[__GDB_BUFMAX];   /* Buffer for GDB to BB messages */
static char  __gdbOutBuffer[__GDB_BUFMAX];  /* Buffer for BB  to GDB messages */
/* Table of symbols that we need to lookup the address of */
/* So far, we don't need to look up any symbols */
#if 1
static gdbSymbol* __gdb_symbol_table = NULL;
#else
/* Sample __gdb_symbol_table.
   Note that the table must be terminated by a NULL entry.*/
                                            /* Name */     /* Address */
static gdbSymbol __gdb_symbol_table[] = { { "osRecvMesg",      NULL },
                                          { "__osDisableInt",  NULL },
                                          { NULL,              NULL } };
#endif

extern OSMesgQueue BKmq;
extern int strlen(const char* s);
extern int strcmp(const char *s1, const char *s2);
extern int strncmp(const char *s1, const char *s2, size_t n);
 
/************************************************************************
 Function: __gdbWriteThreadID
 Args:     char* buf      - Response buffer
           int   threadID - Thread ID
 Purpose:  This function writes the thread ID into the response buffer
           (null-terminated).
 Returns:  char* - Pointer to the character AFTER the last byte written
                   (i.e. position of null-terminator)
************************************************************************/
char* __gdbWriteThreadID(char* buf, int threadID)
{
    /* TODO: does this have to be in big-endian or target order? */
    /* GDB spec says big-endian, BBPlayer also big-endian so we are okay */
    if (buf == NULL) return NULL;
    else return mem2hex((char*) &threadID, buf, sizeof(threadID));
}

/************************************************************************
 Function: gdbWriteThreadList
 Args:     char* ptr     - Response buffer
           u32   limit   - The number of thread ids to report at once
           int   restart - Should we restart the thread list?
 Purpose:  This function writes the list of active thread IDs into the 
           response buffer (null-terminated).  This function will return
           once all active threads IDs or "limit" IDs have been reported.  

           If "restart" is true, then we will start at the begining of 
           the list.  Otherwise, we start where we left off from the 
           previous call.

           The format of the response is:
           m<id1>,<id2>,<id3>,...
           If there are no more thread IDs to report, the list is 
           terminated by a 'l'
 Returns:  Number of threads IDs written.

 TODO: Enhance to check buffer overflow (shouldn't be a problem
       since we are limiting the number of thread IDs reported).
************************************************************************/
int gdbWriteThreadList(char *ptr, u32 limit, int restart)
{
    static OSThread *t = NULL;
    int cnt = 0;
    int isUserThread = 0;
    int tid;
    
    if (ptr == NULL) return 0;

    /* List all thread IDs */
    if (restart)
        t = __gdbGetActiveQueue();

    /* No threads - need to restart */
    if (t == NULL) {
        *ptr++ = 'l';
        *ptr++ = 0;
        return 0;
    }
    
    /* loop through the list of current threads */
    *ptr++ = 'm'; 
    for (; (t != NULL) && (t->priority != -1); t = t->tlnext) 
    {
        isUserThread = __OS_IS_USER_THREAD(t);
        tid = __gdbGetThreadID(t);
        if (gdbShowAllThreadsFlag || isUserThread)
        {

            /* Limit the number of thread IDs that we are reporting
               at once.  We have not reported the current thread
               yet, so the next time we enter this function, we
               will be ready to report it. */
            if (cnt >= limit) return cnt;

            if (cnt > 0)
            {
                /* There was a previous thread */
                *ptr++ = ',';
            } 
            ptr = __gdbWriteThreadID(ptr, tid); /* ptr is now null-terminated */
            cnt++;
        }
         
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: %s Thread %d with id %d\n", gdb_module_name, 
                         isUserThread? "User": "System", cnt, tid);
    }

    /* Set t to NULL so we know that we are done */
    t = NULL;

    return cnt;
}

char* __gdbWriteThreadInfo(char *buf, int threadID)
{
    OSThread *t;
    char* tmp_str;
    char* ptr;
    char  tmp_buf[256];
    int n;

    if (buf == NULL) return NULL;
    /* Find thread */
    t = __gdbIDToThread(threadID);
    if (t == NULL) return NULL;

    ptr = tmp_buf;

    n = sprintf(ptr, "Thread ID %d", (int) t->id);
    ptr += n;

    /* Get priority */
    n = sprintf(ptr, ", Priority %d", (int) t->priority);
    ptr += n;

    /* Get thread state */
    switch (t->state) {
        case OS_STATE_STOPPED:
            tmp_str = "Stopped";
            break;

        case OS_STATE_RUNNABLE:
            tmp_str = "Runnable";
            break;

        case OS_STATE_RUNNING:
            tmp_str = "Running";
            break;

        case OS_STATE_WAITING:
            tmp_str = "Waiting";
            break;

        default:
            tmp_str = "Unknown";
            break;
    }

    n = sprintf(ptr, ", State is %s", tmp_str);
    ptr += n;

    /* Get the RCP (the interrupt mask?) */
    n = sprintf(ptr, ", RCP=0x%x", (int) t->context.rcp);
    ptr += n;
    
    /* ptr should currently be pointing to the null termination */
    /* Convert from text string to hex */
    return mem2hex(tmp_buf, buf, ptr-tmp_buf+1);
}

char* __gdbWriteSignal(char *buf, int sigval) 
{
    if (buf == NULL) return NULL;

    *buf++ =  hexchars[sigval >> 4];
    *buf++ =  hexchars[sigval % 16];
    *buf = 0;
    return buf;
}

char* __gdbWriteSRThreadID(char *buf, int threadID) 
{
    if (buf == NULL) return NULL;

    *buf++ = 't';
    *buf++ = 'h';
    *buf++ = 'r';
    *buf++ = 'e';
    *buf++ = 'a';
    *buf++ = 'd';

    *buf++ = ':';

    buf = __gdbWriteThreadID(buf, threadID);
    *buf++ = ';';
    *buf = 0;
    return buf;
}

char* __gdbStartThreadSignalReply(char *buf, int sigval) 
{
    if (buf == NULL) return NULL;

    *buf++ = 'T';
    buf = __gdbWriteSignal(buf, sigval);
    return buf;
}

void gdbWriteSignalReply(char *buf, int sigval)
{
    if (buf == NULL) return;

    *buf++ = 'S';
    __gdbWriteSignal(buf, sigval);
}

void gdbWriteThreadSignalReply(char *buf, int sigval, int threadID) 
{
    if (buf == NULL) return;

    *buf++ = 'T';
    buf = __gdbWriteSignal(buf, sigval);
    buf = __gdbWriteSRThreadID(buf, threadID);
}

/**************** GDB Symbol Functions **************/

void gdbQuerySymbol(char* buf, gdbSymbol *symbol)
{
    if (buf == NULL) return;

    if ((symbol == NULL) || (symbol->name == NULL))
    {
        /* Done with querying */
        strcpy(buf, GDB_RESP_STATUS_OK);
    }
    else 
    {
        /* Query symbol */
        strcpy(buf, "qSymbol:");
        /* Symbol name need to be in hex */
        mem2hex(symbol->name, &buf[8], strlen(symbol->name));
    }
}

/* Temporary symbol name */
static char __gdb_gt_symname[256];

int gdbAddSymbol(char* hex_symname, gdbSymbol *symbol, u32 addr)
{
    char* tmp;
    int   len;

    if (hex_symname == NULL) return 0;
    if (symbol == NULL) return 0;

    len = strlen(hex_symname)/2;
    if (len >= sizeof(__gdb_gt_symname))  /* Save one character for null-termination */
    {
        /* Argh, we are not prepared to handle symbols with such long names.
           reject with error */
        if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
            GDB_PRINTF("%s: GDB symbol name too long: length=%d, max=%d\n",
                         gdb_module_name, len, sizeof(__gdb_gt_symname));
        return 0;
    }

    tmp = hex2mem(hex_symname, __gdb_gt_symname, len);
    *tmp = 0; /* Null terminate */
    if (gdbDebug & GDB_DEBUG_SHOW_INFO)
        GDB_PRINTF("%s: Address of %s is 0x%x\n", gdb_module_name, __gdb_gt_symname, addr);

    /* Verify that this is the symbol we are looking for */
    if (strcmp(__gdb_gt_symname, symbol->name) == 0) 
    {
        symbol->addr = addr;
        return 1;
    }
    else 
    {
        /* Hmmm, we didn't request this symbol */
        if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
            GDB_PRINTF("%s: Did not request address for %s, requested address of %s\n",
                         gdb_module_name, __gdb_gt_symname, symbol->name);
        /* Let's ignore this response */
        return 0;
    }
}


/************************************************************************
 Function: gdbProcSetThreadPkt
 Args: 	   char* ptr  - Breakpoint command (format: type,address,length)
           char* resp - Response buffer
 Purpose:  This function parses the GDB set thread command and set
           the current thread. This function will also write to the 
           response buffer (null-terminated)
           the status to be sent to GDB:
           OK  - If the operation was successful
           ENN - If there was an error
************************************************************************/
void gdbProcSetThreadPkt(char* ptr, char *resp)
{
    /* Hct... set thread for continue/step 
       or
       Hgt... set thread for general (other operations) 
       t = thread id, -1 for all threads, 0 for any thread
    */
    
    int tid;
    char ch = ptr[0];
    

    if (ch == 'g' || ch == 'c') {                
        ptr++;
        if (hexToInt(&ptr, &tid))    /* get thread id */
        {
            int res = -1;

            if (gdbDebug & GDB_DEBUG_SHOW_INFO)
                GDB_PRINTF("%s: set thread - thread id %d\n", 
                           gdb_module_name, tid);
            
            if (ch == 'g') {
                res = __gdbSetRequestedThread(&__gdb_curThread, tid);
            }
            else if (ch == 'c')
            {
                res = __gdbSetRequestedThread(&__gdb_curRunThread, tid);
            }
            
            if (res >= 0)
            {
                strcpy(resp, GDB_RESP_STATUS_OK);
            } else {
                if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                    GDB_PRINTF("%s: set thread - thread %d not found\n", 
                               gdb_module_name, tid);
                strcpy(resp, GDB_RESP_ERR_NO_THREAD);
            }
        }
        else {
            if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                GDB_PRINTF("%s: set thread - no thread id\n", gdb_module_name);
        }
    }              
    else {
        if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
            GDB_PRINTF("%s: set thread - unknown option %c\n", 
                       gdb_module_name, ch);
    }
}

/************************************************************************
 Function: gdbProcBreakPkt
 Args: 	   char  cmd  - GDB Packet Command 
           char* ptr  - Breakpoint command (format: type,address,length)
           char* resp - Response buffer
 Purpose:  This function parses the GDB breakpoint commands and sets
           the specified register for the current thread.  This function
           will also write to the response buffer (null-terminated)
           the status to be sent to GDB:
           OK  - If the operation was successful
           ENN - If there was an error
 TODO:     Add support for watchpoints
************************************************************************/
void gdbProcBreakPkt(char cmd, char* ptr, char *resp)
{
    int type, addr, length;

    if ((ptr == NULL) || (resp == NULL)) return;

    if (hexToInt(&ptr, &type)
        && (*ptr++ == ',')
        && hexToInt(&ptr, &addr)
        && (*ptr++ == ',')
        && hexToInt(&ptr, &length))
    {
        int res = -1;
        /* Verify addr is a valid address 
           (Assume that the addresses from GDB are virtual) */
        
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: Set/clear breakpoint at 0x%x\n", 
                       gdb_module_name, addr);
        
        if (osVirtualToPhysical( (void*) addr) == -1)
        {
            if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                GDB_PRINTF("%s: Cannot set/clear breakpoint - "
                           "invalid address 0x%x\n", 
                           gdb_module_name, addr);
            strcpy(resp, GDB_RESP_ERR_INVALID_ADDR); 
            return;
        }
        
        switch (type)
        {
            case (GDB_BREAKPT_MEMORY): 
                /* 0 = Memory   breakpoint */
                /* Used with GDB "break" */
                
                /* Need to make sure that GDB doesn't try
                   to send a breakpoint on this thread */
                if (cmd == 'z')
                    res = gdbRemoveBreakpoint(type, (u32*) addr, length);
                else res = gdbInsertBreakpoint(type, (u32*) addr, length);
                break;
                
            case (GDB_BREAKPT_HARDWARE): 
                /* 1 = Hardware breakpoint */
                /* Used with GDB "hbreak" */
                break;
                
            case (GDB_WATCHPT_WRITE): 
                /* 2 = Write  watchpoint */
                break;

            case (GDB_WATCHPT_READ): 
                /* 3 = Read   watchpoint */
                break;

            case (GDB_WATCHPT_ACCESS): 
                /* 4 = Access watchpoint */
                break;

            default: 
                /* Unknown type */
                if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                    GDB_PRINTF("%s: unknown breakpoint type %c\n", 
                               gdb_module_name, type);
                break;        
        }

        if (res >= 0)
            strcpy(resp, GDB_RESP_STATUS_OK);
        else {
            if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                GDB_PRINTF("%s: Cannot set/clear breakpoint at address 0x%x (Error code %d)\n",
                           gdb_module_name, addr, res);
            if (res == GDB_ERROR_NO_MORE_IDS)
                /* No more slots */
                strcpy(resp, GDB_RESP_ERR_NO_MORE_SLOTS);
            else strcpy(resp, GDB_RESP_ERR_OP_FAILED);
        }
    }
    else strcpy(resp, GDB_RESP_ERR_PKT_FORMAT);
}
    

/************************************************************************
 Function: gdbProcPacket
 Purpose:  This function retrieves one GDB packet, processes it, and sends
           the appropriate response back to GDB.
************************************************************************/
void gdbProcPacket()
{
    static gdbSymbol *cur_symbol = NULL;
    OSThread  *t;
    int       addr, length, tid;
    int       sigval = 0;
    char      *ptr;
    char      cmd;

    __gdbOutBuffer[0] = 0;

    /* __gdbGetPacket retrieves one packet and places it in __gdbInBuffer
       __gdbGetPacket will make sure that the packet is null-terminated */
    if (gdbDebug & GDB_DEBUG_SHOW_INFO)
        GDB_PRINTF("%s: Waiting for GDB packet\n", gdb_module_name); 
    __gdbGetPacket(__gdbInBuffer, __GDB_BUFMAX, &sigval);

    if (sigval != 0)
    {
        /* Got an interrupt signal from GDB */
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: Got signal %d from GDB\n", gdb_module_name, sigval);
        gdbStopUserThread(GDB_ALL_THREADS);
        gdbWriteThreadSignalReply(__gdbOutBuffer, sigval, __gdbGetCurrentThreadID());
        __gdbPutPacket(__gdbOutBuffer);
        return;
    }

    if (gdbStopUserThreadsFlag)
    {
        /* Make sure user threads are stopped when interacting with GDB */
        gdbStopUserThread(GDB_ALL_THREADS);
    }

    if (gdbDebug & GDB_DEBUG_SHOW_PACKET)
        GDB_PRINTF("%s: received packet: %s\n", gdb_module_name, __gdbInBuffer);

    cmd = __gdbInBuffer[0];
    switch(cmd) {
        case ('H'): /* Set Thread */
            /* Hct... set thread for continue/step 
               or
               Hgt... set thread for general (other operations) 
               t = thread id, -1 for all threads, 0 for any thread
            */

            /* GDB usually connects with Hc-1 */
            ptr = &__gdbInBuffer[1];
            gdbProcSetThreadPkt(ptr, __gdbOutBuffer);            
            break;

        case ('T'): /* Find out if thread is alive */
            ptr = &__gdbInBuffer[1];
            if (hexToInt(&ptr, &tid))    /* get thread id */
            {
                t = __gdbIDToThread(tid);
                if (t) {
                    strcpy(__gdbOutBuffer, GDB_RESP_STATUS_OK);
                } else {
                    if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                        GDB_PRINTF("%s: thread status - thread %d not found\n", 
                                     gdb_module_name, tid);
                    strcpy(__gdbOutBuffer, GDB_RESP_ERR_NO_THREAD);
                }
            }
            else {
                if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                    GDB_PRINTF("%s: thread state - no thread id\n", gdb_module_name);
            }
            break;            

        case ('q'): /* General Query */
            /* Used for many of the GDB "info ..." commands */
            ptr = &__gdbInBuffer[1];
            if (strcmp(ptr, "C") == 0)
            {
                /* Return the current thread id */
                __gdbOutBuffer[0] = 'Q';
                __gdbOutBuffer[1] = 'C';
                __gdbWriteThreadID(&__gdbOutBuffer[2], __gdbGetCurrentThreadID());
            }
            else if (strcmp(ptr, "fThreadInfo") == 0)
            {
                /* Return a list of active thread ids (first query) */
                int n = gdbWriteThreadList(__gdbOutBuffer, __GDB_THREAD_LIST_LIMIT, 1);
                if (gdbDebug & GDB_DEBUG_SHOW_INFO)
                    GDB_PRINTF("%s: thread info - %d threads found\n", gdb_module_name, n);
            }
            else if (strcmp(ptr, "sThreadInfo") == 0)
            {
                /* Return a list of active thread ids (subsequent queries) */
                int n = gdbWriteThreadList(__gdbOutBuffer, __GDB_THREAD_LIST_LIMIT, 0);
                if ((n > 0) && (gdbDebug & GDB_DEBUG_SHOW_INFO))
                    GDB_PRINTF("%s: thread info - %d more threads found\n", gdb_module_name, n);
            }
            else if (strncmp(ptr, "ThreadExtraInfo", 15) == 0)
            {
                if (gdbDebug & GDB_DEBUG_SHOW_INFO) 
                    GDB_PRINTF("%s: extra thread info\n", gdb_module_name);

                /* Extra thread info */
                /* Format: qThreadExtraInfo,id */
                ptr+=15; /* Skip over ThreadExtraInfo */
                if ((*ptr++ == ',') 
                    && hexToInt(&ptr, &tid))
                {
                    __gdbWriteThreadInfo(__gdbOutBuffer, tid);
                }
            }
            else if (strncmp(ptr, "L", 1) == 0)
            {
                /* Obtain thread infomation from RTOS */
                /* Format: qLstartflagthreadcountnextthread */
                ptr+=1; /* Skip over L */
            }
            else if (strncmp(ptr, "CRC:", 4) == 0)
            {
                /* Compute CRC of memory block */
                /* Format: qCRC:addr,length */
                ptr+=4; /* Skip over CRC: */
            }
            else if (strcmp(ptr, "Offsets") == 0)
            {
                /* Query section offsets */
            }
            else if (strncmp(ptr, "P", 1) == 0)
            {
                /* Thread info request */
                /* Format: qPmodethreadid */
                ptr+=1; /* Skip over P */
            }
            else if (strncmp(ptr, "Rcmd", 4) == 0)
            {
                /* Executes remote command */
                /* Format: qRcmd,command */
                ptr+=4; /* Skip over Rcmd */
            }
            else if (strncmp(ptr, "Symbol:", 7) == 0)
            {
                /* Symbol Lookup */
                /* Format: qSymbol::
                    or     qSymbol:sym_value:sym_name */
                ptr+=7; /* Skip over Symbol: */

                if (*ptr == ':') {
                    /* Ask about osRecvMsg */
                    ptr++;
                    if (*ptr == 0) {
                        /* qSymbol:: */
                        if (__gdb_symbol_table)
                            cur_symbol = &__gdb_symbol_table[0];
                        if (cur_symbol != NULL)
                        {
                            gdbQuerySymbol(__gdbOutBuffer, cur_symbol);
                            break;
                        }
                    }
                    else {
                        /* qSymbol::sym_name */
                        /* Wasn't able to get the address for symbol */
                        gdbAddSymbol(ptr, cur_symbol, 0);
                        if (cur_symbol != NULL)
                        {
                            cur_symbol++;
                            gdbQuerySymbol(__gdbOutBuffer, cur_symbol);
                            break;
                        }
                    }
                }
                else {
                    /* qSymbol:sym_value:sym_name */
                    if (hexToInt(&ptr, &addr)
                        && (*ptr++ == ':'))
                    {
                        gdbAddSymbol(ptr, cur_symbol, addr);
                        if (cur_symbol != NULL)
                        {
                            cur_symbol++;
                            gdbQuerySymbol(__gdbOutBuffer, cur_symbol);
                            break;
                        }
                    }                       
                }

                /* Reply OK if we haven't broken out of the switch */
                strcpy(__gdbOutBuffer, GDB_RESP_STATUS_OK);
            }            
            else 
            {
                if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                    GDB_PRINTF("%s: unknown query %s\n", gdb_module_name, ptr);
            }
            
            break;

        case ('?'): /* Last Signal */
            /* Indicates the reason the program was halted */
            /* Seen when GDB connects */
            gdbWriteThreadSignalReply(__gdbOutBuffer, sigval, __gdbGetCurrentThreadID());
            break;

        case ('g'): /* Read general registers */
            /* Used by GDB to determine thread state and stack backtrace */
            gdbAssembleRegisters(__gdbOutBuffer);
            break;

        case ('P'): /* Pn=value - Write register */
            /* Used by GDB when user sets a register, calls a function */
            /* E.g for setting a register: set $v0=1 */
            ptr = &__gdbInBuffer[1];
            gdbProcSetRegisterPkt(ptr, __gdbOutBuffer);
            break;

        case ('G'): /* Set general registers */
            /* Should we support this? */
            /* Used by GDB when P command not supported? */
            break;

        case ('z'): /* ztype,addr,length - Remove breakpoint or watchpoint */
        case ('Z'): /* Ztype,addr,length - Insert breakpoint or watchpoint */
            /* Parse for type, addr, and length */
            ptr = &__gdbInBuffer[1];
            gdbProcBreakPkt(cmd, ptr, __gdbOutBuffer);
            break;

        case ('c'):   /* cAA..AA    Continue at address AA..AA(optional) */
            /* Used by GDB for continue/step/next etc */
            ptr = &__gdbInBuffer[1];
            if (hexToInt(&ptr, &addr))
            {
                /* Continue thread at given address */
                gdbRunThread(__gdb_curRunThread, KK_VADDR, addr);
            }
            else
            {
                /* Continue thread */
                gdbRunThread(__gdb_curRunThread, 0, 0);
            }

            /* ### need to flush the cache !*/

            /* Check flag to see if we are going to sync with another thread */
            if (gdbWaitToSendBreakFlag)
            {
                /* Send message that we are waiting for a breakpoint to happen */
                if (gdbDebug & GDB_DEBUG_SHOW_INFO)
                    GDB_PRINTF("%s: waiting for target to halt\n", gdb_module_name);
                
                if (osSendMesg(&BKmq, NULL, OS_MESG_NOBLOCK) < 0)
                    if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                        GDB_PRINTF("%s: Unable to send message that we are waiting"
                                     "for target to halt\n", gdb_module_name);
            }

            /* Do not need to send packet - just return */
            return;
              
       case ('s'):   /* sAA..AA    Step at address AA..AA(optional) */
            /* Not observed in GDB with target="mips-linux"
               If SOFTWARE_SINGLE_STEP_P() is defined to be 1, GDB will automatically 
                  insert/remove breakpoints for stepping and will not use 's'.
               To use 's' for stepping, define SOFTWARE_SINGLE_STEP_P() to be 0
            */
            ptr = &__gdbInBuffer[1];
            if (hexToInt(&ptr, &addr))
            {
                /* Step thread at given address */
                gdbRunThread(__gdb_curRunThread, KK_VADDR | KK_STEP, addr);
            }
            else
            {
                /* Step thread */
                gdbRunThread(__gdb_curRunThread, KK_STEP, 0);
            }

            /* ### need to flush the cache !*/

            /* Check flag to see if we are going to sync with another thread */
            if (gdbWaitToSendBreakFlag)
            {
                /* Send message that we are waiting for a breakpoint to happen */
                if (gdbDebug & GDB_DEBUG_SHOW_INFO)
                    GDB_PRINTF("%s: waiting for target to halt\n", gdb_module_name);
                
                if (osSendMesg(&BKmq, NULL, OS_MESG_NOBLOCK) < 0)
                    if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                        GDB_PRINTF("%s: Unable to send message that we are waiting"
                                     " for target to halt\n", gdb_module_name);
            }

            /* Do not need to send packet - just return */
            return;

       case ('D'):
            /* GDB detaching - let's clear all breakpoints and resume the program */           
            gdbRemoveAllBreakpoints();
            gdbRunThread(GDB_ALL_THREADS, 0, 0);
            break;
             
       case ('M'):
            /* MAA..AA,LLLL: Write LLLL bytes at addr AA.AA return
               OK */
            /* Try to read '%x,%x:'.  */

            /* Used by GDB when user types: set <variable>=<value> */
            /* E.g: set gdbDebug=0 */
            ptr = &__gdbInBuffer[1];            
            if (hexToInt(&ptr, &addr)
                && *ptr++ == ','
                && hexToInt(&ptr, &length)
                && *ptr++ == ':')
            {
                /* Verify addr is a valid address (we are assuming that the 
                   addresses from GDB are virtual addresses)
                   then write value from buffer (ptr) into addr */
                if ((osVirtualToPhysical((void*) addr) != -1) &&
                    hex2mem(ptr, (char *)addr, length)) 
                {
                    /* Let's use the GDB versions so users can put breakpoints
                       in the os versions without affecting us */
                    gdbWritebackDCache((void *)addr, length);
                    gdbInvalICache((void *)addr, length);
                    strcpy(__gdbOutBuffer, GDB_RESP_STATUS_OK);
                } else
                    strcpy(__gdbOutBuffer, GDB_RESP_ERR_INVALID_ADDR);
            }
            else
                strcpy(__gdbOutBuffer, GDB_RESP_ERR_PKT_FORMAT);
            break;
            
        case ('m'):   /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
            /* Try to read %x,%x.  */

            /* ### need to handle read fault! */
            ptr = &__gdbInBuffer[1];
            
            if (hexToInt(&ptr, &addr)
                && *ptr++ == ','
                && hexToInt(&ptr, &length))
            {
                /* Verify addr is a valid address (we are assuming that the 
                   addresses from GDB are virtual addresses)
                   then copy value from addr to __gdbOutBuffer */
                if ((osVirtualToPhysical((void*) addr) != -1) &&
                    mem2hex((char *)addr, __gdbOutBuffer, length))
                {
                    /* Success - Nothing to do */
                }
                else {
                    strcpy (__gdbOutBuffer, GDB_RESP_ERR_INVALID_ADDR);
                }
            }
            else
                strcpy(__gdbOutBuffer, GDB_RESP_ERR_PKT_FORMAT);

            break;

        case ('k'):
            /* Kill the program */
            /* For now, let's just stop the user threads */
            gdbStopUserThread(GDB_ALL_THREADS);
            break;

        default:
            /* Unsupported command - will respond with empty 
               packet (i.e. $#00) */
            if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                GDB_PRINTF("%s: unsupported command %s\n", 
                           gdb_module_name, __gdbInBuffer);
            break;
        
    }

    __gdbPutPacket(__gdbOutBuffer);
}