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188.8.131.52. Abstract Commands in Debug Mode
Nios® V/m processor implements Access Register abstract command. The Access Register command allows read-write access to the processor registers including GPRs, CSRs, FP registers and Program Counter. The Access Register also allows program execution from program buffer. The debugger executes Access Register commands by writing into Abstract Command (command) register using the Access Register command encoding.
|cmdtype||Determine command type
0 : Indicates Access Register command.
|aarsize||Specifies size of register access
2: Access the lowest 32 bit of register
3: Access the lowest 64 bit of register
4: Access the lowest 128 bit of register
|aarpostincrement||0: No effect
1: regno is incremented after successful register access
0: No effect1: Execute program in program buffer
Acts in conjunction with write field.
0: Ignore value in write field1: Execute operation specified by write field.
0: Copy data from register1: Copy data to register
|regno||Register address to be accessed.|
|2||Command not supported|
|3||Exception - from program buffer instruction|
|4||Command not executed because hart unavailable, or not in correct state to execute command.|
|5||Abstract command failed due to bus error|
|7||Command failed for other reasons.|
Avalon® memory-mapped interface implement the Register Access using request/response bus with Debug Module being the initiator and core being the responder. Address bus carries the register ID.
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