Simulation Pipeline Modes (C2000 & C5000)

Simulation Pipeline Modes for C2000 and C5500 CA Simulators

C55x and C28x Cycle Accurate simulators support two modes of execution called Pipeline Flush mode and Pipelined mode.

• In Pipeline Flush mode, when the simulation is halted, the execution pipeline is flushed. The watch window shows the correct values of local variables in this mode. Profile data may be skewed because of flushing the pipeline whenever the simulation halts. This skew is noticeable only if there are many breakpoints in the program.
  • The PC (program counter) corresponds to the address of the instruction that is about to enter the Decode phase of the pipeline.
• In Pipelined mode, when the simulation is halted, the execution pipeline is not flushed. Pipline behavior is accurate in this mode. This mode provides accurate profile data. The watch window display may not show the correct values of local variables.
  • The PC corresponds to the address of the instruction that is about to enter the Execute phase of the pipeline.

Switching Between the Modes

Configuring in CCSv3.3

Pipeline Flush mode is the default simulation mode. The mode can be changed using the following mechanisms:

• From the Code Composer Studio Debug Menu, by enabling/disabling Flush Pipeline on Halt.

 

• From Tools-> Command Window plug-in - Command "EMU" will change to Pipeline Flush mode and command "SIM" will change to Pipelined mode.

Configuring in CCSv4

The Simulation mode can be configured using Target menu/debug option.

Clicking on the Debug button will pop up a debug window as shown below. Then click on the Target Tab and enable/disable the simulators will flush the pipeline on a haltto change the mode.

Note: In CCSv3, the simulation mode can be changed at any point of time after launching the simulator. But in CCSv4, the simulation mode can be configured only before launching the simulator and can not be changed once the Simulator is launched.

Effects of Mode Switching

From Pipeline Flush mode to Pipelined mode:

• Simulation advances the pipeline to bring the PC to the execution phase
• After mode switching, the PC points to the instruction in the Execute phase of the pipeline

From Pipelined mode to Pipeline Flush mode

• Simulation flushes the pipeline.
• After mode switching, the PC points to the instruction in the Decode phase of the pipeline. However,this effect is hidden from the user unless the user does an Instruction Step after the mode change. If an Instruction Step is done after mode change, the user might see skid of a few instructions in the assembly window and PC changing in the register window.
• Breakpoints that have been set at instructions which are being flushed out of the pipeline are ignored.

Recommendations on Simulation Mode

• Use Pipelined Mode for Application Code Profiling and Tuning.
• Use Pipeline Flush Mode for Application Debug.