ARM R4F, r1p3 manual Debug state exit, Example 11-12 Leaving debug state

Debug

dscr := ReadDebugRegister(34);

}

until (dscr & (1<<19));

}

//Step 4. Read the entire processor state. The function ReadAllRegisters

//reads all general-purpose registers for all processor mode, and saves

//the data in “state”.

ReadAllRegisters(state);

//Step 5. Based on the CPSR (processor state), determine the actual restart

//address

if (state->cpsr & (1<<5);

{

//set the T bit to Thumb state state->pc := state->pc - 4;

}

elseif (state->cpsr & (1<<24))

{

//Set the J bit to Jazelle state. Note: ARM Cortex-R4 does not support

//Jazelle state but ARMv7 debug does.

state->pc := state->pc - IMPLEMENTATION DEFINED

value;

}

else

{

// ARM state

state->pc := state->pc - 8;

}

//Step 6. If the method of entry was Watchpoint Occurred, read the WFAR

//register

method_of_debug_entry := ((state->dscr >> 2) & 0xF;

if (method_of_debug_entry == 2 method_of_debug_entry == 10)

{

state->wfar := ReadDebugRegister(6);

}

}

11.11.5 Debug state exit

When exiting debug state, the program counter must always be written. If the execution state or CPSR must be changed, this must be done before writing to the PC because writing to the CPSR can affect the PC.

Having restored the program state, the debugger can restart by writing to bit [1] of the Debug Run Control Register. It must then poll bit [1] of the Debug Status and Control Register to determine if the core has restarted.

Example 11-12shows the code for exit from debug state.

Example 11-12 Leaving debug state

ExitDebugState(PROCESSOR_STATE *state)

{

//Step 1. Update the CPSR value WriteCPSR(state->cpsr);

//Step 2. Restore any registers corrupted by debug state. The function

//WriteAllRegisters restores all general-purpose registers for all

//processor modes apart from R0.

WriteAllRegisters(state);

// Step 3. Write the return address.

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