/*---------------------------------------------------------------------*
 *  Copyright (C) 2004 BroadOn Communications Corp.
 *                 
 *  $RCSfile: gdbthreads.c,v $ (derived from rmontask.c)
 *  $Revision: 1.4 $
 *  $Date: 2004/02/24 20:50:31 $
 *---------------------------------------------------------------------*/

/* 
 * This file provides the thread handling functions for the GDB stub
 * for debugging the BBPlayer
 */

#include "ultragdb.h"
#include <R4300.h>
#include <sys/signal.h>

extern OSThread *__osActiveQueue;
extern OSThread  __osThreadSave;
extern OSThread *__osRunningThread;

/* Separate buffer for BB to GDB messages for when a breakpoint 
   is encountered.  This is used by the gdbMain thread. */
static char  __gdbBreakBuffer[__GDB_BUFMAX];
static int   __gdbUserThreadsStopped = 0;

OSThread *__gdb_curRunThread = GDB_ALL_THREADS; /* Thread for continue/step commands */
OSThread *__gdb_curThread = GDB_ALL_THREADS;    /* Thread for other commands */

/**************** GDB Thread Support Functions **************/

OSThread* __gdbGetActiveQueue(void) /* Same as __osGetActiveQueue */ 
{
	return (__osActiveQueue);
}

int __gdbGetThreadID(OSThread* t)
{
#if GDB_USE_THREADID
    /* Use the thread ID from the structure */
    if (t == NULL) return 0;
    if (t == GDB_ALL_THREADS) return -1;
    return t->id;
#else
    /* Use the physical address as the thread id */
    /* Don't use the virtual address because 
       GDB does something funny with negative numbers */
    return osVirtualToPhysical(t);
#endif
}

/************************************************************************
 Function: __gdbFindIdleThread
 Purpose:  This function finds the idle thread (i.e. priority is 0)
 Returns:  OSThread* - Pointer to the idle thread, NULL if none found.
************************************************************************/
OSThread* __gdbFindIdleThread() 
{
    OSThread *t;
    
    /* Finds and returns the idle thread */
    
    /* loop through the list of current threads */
    for (t = __gdbGetActiveQueue(); (t != NULL) && (t->priority != -1); t = t->tlnext) 
    {
        if (__OS_IS_IDLE_THREAD(t)) {
            return t;
        }
    }

    if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
        GDB_PRINTF("%s: Idle thread not found\n", gdb_module_name);

    return NULL;
}


/************************************************************************
 Function: __gdbFindUserThread
 Purpose:  This function finds a user thread (i.e. priority from 1 to 127)
 Returns:  OSThread* - Pointer to a user thread, NULL if none found.
************************************************************************/
OSThread* __gdbFindUserThread() 
{
    OSThread *t;
    
    /* Finds and returns the user thread */
    
    /* loop through the list of current threads */
    for (t = __gdbGetActiveQueue(); (t != NULL) && (t->priority != -1); t = t->tlnext) 
    {
        if (__OS_IS_USER_THREAD(t)) {
            return t;
        }
    }

    if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
        GDB_PRINTF("%s: User thread not found\n", gdb_module_name);

    return NULL;
}

/************************************************************************
 Function: gdbGetSignal
 Args: 	   u32 cause - The R4300 cause register
 Purpose:  This function takes the cause of a break/fault and determines
           the appropriate signal to send to GDB.
 Returns:  int - GDB signal corresponding to the cause

************************************************************************/
int gdbGetSignal( u32 cause )
{
    int sig;
    
    switch (cause & CAUSE_EXCMASK) {
      case (EXC_INT):     sig = SIGINT;  break; /* interrupt */
      case (EXC_BREAK):   sig = SIGTRAP; break; /* BREAKpoint */
      case (EXC_WATCH):   sig = SIGTRAP; break; /* Watchpoint reference */
      case (EXC_TRAP):    sig = SIGTRAP; break; /* Trap exception */
      case (EXC_RADE):    sig = SIGSEGV; break; /* Read Address Error */
      case (EXC_WADE):    sig = SIGSEGV; break; /* Write Address Error */
      case (EXC_RMISS):   sig = SIGSEGV; break; /* Read TLB Miss */
      case (EXC_WMISS):   sig = SIGSEGV; break; /* Write TLB Miss */
      case (EXC_IBE):     sig = SIGBUS;  break; /* Instruction Bus Error */
      case (EXC_DBE):     sig = SIGBUS;  break; /* Data Bus Error */
      case (EXC_II):      sig = SIGILL;  break; /* Illegal Instruction */
      case (EXC_FPE):     sig = SIGFPE;  break; /* Floating Point Exception */
      case (EXC_SYSCALL): sig = SIGSYS;  break; /* SYSCALL */
      default:            sig = 7;              /* software generated */
    }
    
    return sig;
}
/************************************************************************
 Function: __gdbIDToThread
 Args:     int   threadID - Thread ID
 Purpose:  This function returns a pointer to the OSThread structure
           given a threadID.  
 Returns:  OSThread* - Pointer to thread with given thread ID
           NULL if there are no threads with the given thread ID
************************************************************************/
OSThread * __gdbIDToThread(int threadID) 
{
    OSThread *t;
    
    /* loop through the list of current threads */
    for (t = __gdbGetActiveQueue(); (t != NULL) && (t->priority != -1); t = t->tlnext) 
    {
        if (__gdbGetThreadID(t) == threadID) {
            return t;
        }
    }

    if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
        GDB_PRINTF("%s: Thread 0x%x not found\n", gdb_module_name, threadID);

    return NULL;
}

/************************************************************************
Function: (static) __gdbRunThread
Args: OSThread* tptr - Pointer to thread
      int flags      - The flags field specifies actions:
                        KK_STEP: single step
		                KK_VADDR: set PC before running
		                KK_ABORT: commit suicide (NOT IMPLEMENTED)
      int addr       - Address at which to continue running
Type: int - returns 0 if successful, otherwise error type (<0)
Purpose: This function is a GDB internal function that runs the 
         specified thread.  DO NOT call this function directly, use
         gdbRunThread instead.
************************************************************************/

static int __gdbRunThread(OSThread* tptr, int flags, int addr)
{
	register int runNeeded = 0;

    /* Is this a legitimate thread? */
    if ((tptr == NULL) || (tptr->priority == -1))
        return GDB_ERROR_INVALID_ID;

    if ( tptr->state != OS_STATE_STOPPED )
        return GDB_ERROR_OP_PROTECTED;

    tptr->flags &= ~3;	/* neither break nor fault */
    if (flags & KK_VADDR )	/* set new pc */
        tptr->context.pc = addr;
    if (flags & KK_STEP )
        if ( !__gdbSetSingleStep( tptr, (u32 *) tptr->context.pc ) )
            return GDB_ERROR_OP_PROTECTED;
    runNeeded = 1;

	if ( runNeeded )
		osStartThread( tptr );

	return GDB_ERROR_NO_ERROR;	/* Dispatch the app */
}

/************************************************************************
Function: gdbRunThread
Args: OSThread* thread - Pointer to thread
      int flags        - The flags field specifies actions:
                          KK_STEP: single step
		                  KK_VADDR: set PC before running
		                  KK_ABORT: commit suicide (NOT IMPLEMENTED)
      int addr         - Address at which to continue running
Type: int - returns 0 if successful, otherwise error type (<0)
Purpose: This function runs the specified thread.  It runs all threads
         if thread is GDB_ALL_THREADS (-1).
************************************************************************/
int gdbRunThread(OSThread* thread, int flags, int addr)
{
    if (thread == GDB_ALL_THREADS)
    {
        /* Run all threads */
        OSThread* t;
        int err;
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: Starting all threads\n", gdb_module_name);
        for (t = __gdbGetActiveQueue(); (t != NULL) && (t->priority != -1); t = t->tlnext) 
        {
            err = __gdbRunThread(t, flags, addr);
        }        
        __gdbUserThreadsStopped  = 0;
        return GDB_ERROR_NO_ERROR;
    }
    else {
        if (thread != NULL)
        {
            __gdbUserThreadsStopped  = 0;
            return __gdbRunThread(thread, flags, addr);
        }
        return GDB_ERROR_INVALID_ID;
    }
}

/************************************************************************
Function: gdbFindFaultedThreads
Purpose:  This function finds all threads that have faulted due to
          a breakpoint or otherwise, and sends a message to the host.
          This function is called from the gdbMain thread when breakpoint
          is hit.  It will need to synchronize with the gdbIOHandler thread
          to make sure that the message is sent only when GDB is expecting
          it.
TO FIX:   What if different threads have different fault states/signals??
          The GDB serial protocol doesn't seem able to handle that.
************************************************************************/
extern OSMesgQueue BKmq;

void gdbFindFaultedThreads( void )
{
    int nfaulted = 0;
    OSThread* t;
    OSThread* faultedThread = NULL;
    char* buf = &__gdbBreakBuffer[0];

    buf[0] = 0;

    /* loop through the list of current threads */
    for (t = __gdbGetActiveQueue(); (t != NULL) && (t->priority != -1); t = t->tlnext) 
    {
        int isUserThread = __OS_IS_USER_THREAD(t);
        int tid = __gdbGetThreadID(t);

        if (gdbShowAllThreadsFlag || isUserThread)
        {
            int inst = 0;
            int cause = t->context.cause;
            int sigval = gdbGetSignal(cause);

            if (t->flags & OS_FLAG_CPU_BREAK || t->flags & OS_FLAG_FAULT)
            {
                if (nfaulted == 0)
                {
                    /* First fault - start message */
                    buf = __gdbStartThreadSignalReply(buf, sigval);
                    faultedThread = t;
                }
                nfaulted++;

                if (gdbDebug & GDB_DEBUG_SHOW_INFO)
                {
                    if (t->flags & OS_FLAG_FAULT) 
                    {
                        GDB_PRINTF("%s: Fault in thread %d at 0x%08x"
                                   "due to cause=0x%x, signal=%d\n",
                                   gdb_module_name, tid, t->context.pc, 
                                   cause, sigval);                        
                        __gdbSendFault( t );
                    }
                    else {
                        inst = * (int*) t->context.pc;
                        GDB_PRINTF("%s: Break in thread %d at 0x%08x, inst 0x%08x "
                                   "due to cause=0x%x, signal=%d\n",
                                   gdb_module_name, tid, t->context.pc, 
                                   inst, cause, sigval);                        
                    }
                }

                buf = __gdbWriteSRThreadID(buf, tid);
            }
        }
    }

    if (gdbDebug & GDB_DEBUG_SHOW_INFO)
        GDB_PRINTF("%s: %d faulted threads found.\n", 
                   gdb_module_name, nfaulted);

    if (nfaulted == 0) return; /* No faulted threads */

    /* Check flag to see if we are going to sync with another thread */
    if (gdbWaitToSendBreakFlag)
    {
        /* Wait for GDB to need a breakpoint message */
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: waiting for GDB to be ready to get target status\n",
                       gdb_module_name);
        
        osRecvMesg(&BKmq, NULL, OS_MESG_BLOCK);
    }

    /* At this point, GDB is waiting for the target to halt and will
       not be sending data to the GDB IO processing thread */
    /* Let's switch to the thread that faulted */
    if (faultedThread) __gdb_curThread = faultedThread;
    __gdbPutPacket(__gdbBreakBuffer);
}


/************************************************************************
Function: __gdbMaskIdleThreadInts
Args: none
Type: void
Purpose: This function is called when a fault occurs to change the idle
   	     thread interrupt mask to allow only debugger interrupts to get
	     through.
************************************************************************/
void __gdbMaskIdleThreadInts( void )
{
	register OSThread * tptr = __gdbGetActiveQueue();

	while ( tptr->priority != -1 )
	{
		if ( tptr->priority == 0 )	/* found it */
		{
			tptr->context.sr &= ~OS_IM_CPU;
			tptr->context.sr |= (OS_IM_CART |
				OS_IM_RDBWRITE | OS_IM_RDBREAD);
			break;
		}
		tptr = tptr->tlnext;
	}
}

/************************************************************************
Function: (static) __gdbStopThread
Args:     OSThread* tptr - Pointer to thread to stop.
Returns: int - Thread ID if the thread was successfully stop. 
               Error code (<0) otherwise.
                GDB_ERROR_INVALID_ID - Invalid thread.
                GDB_ERROR_OP_FAILED  - Cannot stop thread.
Purpose: This function stops the specified thread.
************************************************************************/
static int __gdbStopThread(OSThread* tptr)
{
    if (tptr == NULL) return GDB_ERROR_INVALID_ID;
    osStopThread( tptr );
    if ( tptr->state != OS_STATE_STOPPED )
    {
        if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
            GDB_PRINTF("%s: Couldn't stop thread %d\n", 
                       gdb_module_name, __gdbGetThreadID(tptr) );
        return GDB_ERROR_OP_FAILED;
    }
    return __gdbGetThreadID(tptr);
}

/************************************************************************
Function: gdbStopUserThread
Args:     OSThread* tptr - Pointer to thread to stop.
                           GDB_ALL_THREADS (-1) for all user threads.
Type: int - the ID of the thread that stopped, or 0 if unknown
            If the thread was not stopped, then an error code (<0) 
            is returned:
                GDB_ERROR_INVALID_ID   - Invalid thread.
                GDB_ERROR_OP_FAILED    - Cannot stop thread.
                GDB_ERROR_OP_PROTECTED - Was not a user thread or no idle thread.
Purpose: This function stops one or more running threads. If a thread number
	is specified, then the function was called from the explicit stop
	thread command. If zero, then it was called in response to a break
	or fault being hit, which (for now) stops all threads from running. 
************************************************************************/
int gdbStopUserThread(OSThread* tptr)
{
    if (__gdbUserThreadsStopped) /* Threads already stopped */
        return GDB_ERROR_NO_ERROR;

    if (tptr == GDB_ALL_THREADS)
    {
        OSThread* t;

       /* Let's always set this even if we can't stop the threads so we
          don't annoy the user with the messages */
        __gdbUserThreadsStopped = 1;

        /* Make sure we have a idle thread - otherwise if we stop all the
           user threads, we may lock up the system */
        t =  __gdbFindIdleThread();
        if (t == NULL)
        {
            /* Always print this message - very nasty!!! */
            GDB_PRINTF("%s: WARNING - No idle (priority = %d) thread found!!!."
                       " Refusing to stop user threads for debugging!!!.\n",
                       gdb_module_name, OS_PRIORITY_IDLE);
            return GDB_ERROR_OP_PROTECTED;            
        }

        for (t = __gdbGetActiveQueue(); (t != NULL) && (t->priority != -1); t = t->tlnext)
        {
            int isUserThread = __OS_IS_USER_THREAD(t);

            if (isUserThread)
            {
                __gdbStopThread(t);
            }
        }
        return GDB_ERROR_NO_ERROR;
    }
    else if (tptr != NULL) 
    {
        int isUserThread = __OS_IS_USER_THREAD(tptr);
        if (isUserThread)
        {
            return __gdbStopThread( tptr );
        }
        return GDB_ERROR_OP_PROTECTED;
    }
    else return GDB_ERROR_INVALID_ID;
}


OSThread* getOneCurrentThread()
{
    OSThread* tmp_thread;

    if (__gdb_curThread == NULL)
    {
        /* No Thread selected - lets get the idle thread */
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: No thread selected, using user or idle thread\n",
                       gdb_module_name);

        tmp_thread = __gdbFindUserThread();
        if (tmp_thread == NULL)
            tmp_thread = __gdbFindIdleThread();

        __gdb_curThread = tmp_thread;
    }
    else if (__gdb_curThread == GDB_ALL_THREADS)
    {
        if (gdbDebug & GDB_DEBUG_SHOW_INFO)
            GDB_PRINTF("%s: All thread selected, using user or idle thread\n", 
                       gdb_module_name);

        /* All threads selected - just return user/idle thread */
        tmp_thread = __gdbFindUserThread();
        if (tmp_thread == NULL)
            tmp_thread = __gdbFindIdleThread();

        return tmp_thread;
    }

    return __gdb_curThread;
}

int __gdbGetCurrentThreadID()
{
    OSThread* t = getOneCurrentThread();
    if (__gdb_curThread == NULL)
    {
        if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
            GDB_PRINTF("%s: No thread selected and no user or idle threads, 
                          using debugging thread ID\n", gdb_module_name);
        return __gdbGetThreadID(__osRunningThread);
    }
    else return __gdbGetThreadID(t);
}

int __gdbSetRequestedThread(OSThread** thread, int tid)
{
    OSThread* tmp_thread;

    if (thread == NULL) return -1;

    if (tid == -1) {
        /* All Threads */
        *thread = GDB_ALL_THREADS;
    }
    else if (tid == 0) {
        /* Pick any thread - this is so vague, let's pick all threads just 
         * to be sure. This is useful for handling the following scenario:
         * If someone does "set scheduler-lock on", then GDB will set the
         * run thread to the current thread.  
         * But if someone does "set scheduler-lock off" after that, GDB
         * will set the run thread to 0.  In this case, we really want
         * GDB to continue all threads again, not just any old thread.
         **/
        *thread = GDB_ALL_THREADS;
    }
    else {
        tmp_thread = __gdbIDToThread(tid);
        if (tmp_thread) {
            *thread = tmp_thread;
        } else {
            if (gdbDebug & GDB_DEBUG_SHOW_ERROR)
                GDB_PRINTF("%s: unknown thread %d\n", gdb_module_name, tid);
            /* Didn't find a thread - set error */
            return GDB_ERROR_INVALID_ID;
        }
    }

    if (gdbDebug & GDB_DEBUG_SHOW_INFO)
        GDB_PRINTF("%s: Selected thread 0x%x, thread ID %d\n", 
                     gdb_module_name, *thread, __gdbGetThreadID(*thread));

    return GDB_ERROR_NO_ERROR;
}