stall-sample.dml

/* the first device */
//---> here some signal interface is triggering actions, namely jtag operations via bitbang 
//     this takes care of retry operations if a read was stalled
// clock raise  may call read
// clock lower re-does the read if stalled on raise

//---> here device 2 is connected to 
connect memory
{
   interface memory_space
      {
      parameter required=true;
      }

   method read(uint32 Address, int Len) -> (uint32 data, exception_type_t exc)
      {
      local buffer_t buffer;
      local generic_transaction_t mop;
      exc=Sim_PE_IO_Not_Taken;
      if($memory_space)
         {
         $Regs.CSW.TrInProg=0;
         buffer.data = cast(&data,uint8*);
         buffer.len = Len;
         mop = SIM_make_mem_op_read(Address, buffer, false,$obj);
         exc=$memory_space.access(&mop);
//---> goal is to see the exc==Sim_PE_Stall_Cpu that occured in second device
         if(exc==Sim_PE_Stall_Cpu)
           $CapturePending=true;
         else
           $CapturePending=false;
         }
}


/* the second device */

bank regs
{
      register CSW @ 0x00;
      register TARH @ 0x04;
      register TARL @ 0x08;
      register DRW @ 0x0C
         {
         data bool read_pending;
//---> get called from first device above via memory.read(...)
         method before_read(generic_transaction_t *mop)
            {
            local exception_type_t exc;
            local int size;
            local uint32 ret;
            size=$CSW[3:0];
            call $memory.read($TARH<<32|$TARL,size,mop) -> (ret,exc);
            if(exc==Sim_PE_Stall_Cpu)
               {
//---> what we need to do here so first device will see the stall ???
               $read_pending=true;
               log info,1:"DRW before read returned exc==Sim_PE_Stall_Cpu";
               }
             else
               {
               $this=ret;
               $read_pending=false;
               }
            }
         }
}

//---> here a memory link is connected to 
connect memory
{  
   interface memory_space
      {
      parameter required=true;
      }

   method read(uint32 Address, int Len) -> (uint32 data, exception_type_t exc)
      {  
      local buffer_t buffer;
      local generic_transaction_t mop;
      exc=Sim_PE_IO_Not_Taken;
      $Regs.CSW.TrInProg=0;
      buffer.data = cast(&data,uint8*);
      buffer.len = Len;
      mop = SIM_make_mem_op_read(Address, buffer, false, $obj);
//--->  here we may get the exc==Sim_PE_Stall_Cpu from a memory link 
//we return that to the caller (register DRWs before_read method
      exc=$memory_space.access(&mop);
      }
}