Mirrored HWIO Wrapper

Mirrored HWIO Wrapper#

class peakrdl_pyral_runtime.hwio.mirror.MirroredHWIOWrapper(hwio: HWIO)#

Wrapping HWIO implementations with the MirroredHWIOWrapper class provide a mechanism to maintain a mirrored state of hardware’s memory map.

This can be useful when interfacing with devices that have costly access times. For example, rather than reading from the hardware when performing a read-modify-write operation, one could use this mirror to retain the assumed state of the register being modified.

Any HWIO interface can be mirrored by wrapping it in this class as follows:

my_hwio = MirroredHWIOWrapper(OpenOCDHWIO())

By default, behavior is as follows:

Read operations

  • Perform a read using the hwio class provided to this wrapper.

  • Update the mirrored state with the value read

  • Return the value

Write operations

  • Update the mirrored state with the value provided

  • Write the value using the hwio class provided to this wrapper.

The above behavior can be augmented using the read_from_mirror() and write_to_mirror_only() context managers.

Important

The mirroring mechanism this class implements makes no attempt to model the hardware’s register map behavior beyond what is described above. Be careful when mirroring hardware registers that have access side-effects such as read-clear, write-1-to-clear, volatile fields, etc.

Any advanced modeling of the hardware is out of scope for this project.

hwio#

Reference to the original HWIO class being wrapped.

read_from_mirror() → Generator[None, Any, None]#

Provides a context manager where, when entered, will redirect any read operations that target this HWIO to pull values from the mirrored state rather than the actual hardware.

x = ral.my_reg.read() # Returns value read from the hardware

with my_hwio.read_from_mirror():
    x = ral.my_reg.read() # Returns value from the mirror instead of hardware
write_to_mirror_only() → Generator[None, Any, None]#

Provides a context manager where, when entered, will skip writes to the hardware and only update the mirrored state.

ral.my_reg.write(123) # Writes value to both the hardware and mirror

with my_hwio.write_to_mirror_only():
    ral.my_reg.write(123) # Writes value to mirror only