artiq/artiq/coredevice/dma.py

116 lines
3.7 KiB
Python

"""Direct Memory Access (DMA) extension.
This feature allows storing pre-defined sequences of output RTIO events into
the core device's SDRAM, and playing them back at higher speeds than the CPU
alone could achieve.
"""
from artiq.language.core import syscall, kernel
from artiq.language.types import TInt32, TInt64, TStr, TNone, TTuple
from artiq.coredevice.exceptions import DMAError
from numpy import int64
@syscall
def dma_record_start(name: TStr) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall
def dma_record_stop(duration: TInt64) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall
def dma_erase(name: TStr) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall
def dma_retrieve(name: TStr) -> TTuple([TInt64, TInt32]):
raise NotImplementedError("syscall not simulated")
@syscall
def dma_playback(timestamp: TInt64, ptr: TInt32) -> TNone:
raise NotImplementedError("syscall not simulated")
class DMARecordContextManager:
"""Context manager returned by ``CoreDMA.record()``.
Upon entering, starts recording a DMA trace. All RTIO operations are
redirected to a newly created DMA buffer after this call, and ``now``
is reset to zero.
Upon leaving, stops recording a DMA trace. All recorded RTIO operations
are stored in a newly created trace, and ``now`` is restored to the value
it had before the context manager was entered.
"""
def __init__(self):
self.name = ""
self.saved_now_mu = int64(0)
@kernel
def __enter__(self):
dma_record_start(self.name) # this may raise, so do it before altering now
self.saved_now_mu = now_mu()
at_mu(0)
@kernel
def __exit__(self, type, value, traceback):
dma_record_stop(now_mu()) # see above
at_mu(self.saved_now_mu)
class CoreDMA:
"""Core device Direct Memory Access (DMA) driver.
Gives access to the DMA functionality of the core device.
"""
kernel_invariants = {"core", "recorder"}
def __init__(self, dmgr, core_device="core"):
self.core = dmgr.get(core_device)
self.recorder = DMARecordContextManager()
self.epoch = 0
@kernel
def record(self, name):
"""Returns a context manager that will record a DMA trace called ``name``.
Any previously recorded trace with the same name is overwritten.
The trace will persist across kernel switches."""
self.epoch += 1
self.recorder.name = name
return self.recorder
@kernel
def erase(self, name):
"""Removes the DMA trace with the given name from storage."""
self.epoch += 1
dma_erase(name)
@kernel
def playback(self, name):
"""Replays a previously recorded DMA trace. This function blocks until
the entire trace is submitted to the RTIO FIFOs."""
(advance_mu, ptr) = dma_retrieve(name)
dma_playback(now_mu(), ptr)
delay_mu(advance_mu)
@kernel
def get_handle(self, name):
"""Returns a handle to a previously recorded DMA trace. The returned handle
is only valid until the next call to :meth:`record` or :meth:`erase`."""
(advance_mu, ptr) = dma_retrieve(name)
return (self.epoch, advance_mu, ptr)
@kernel
def playback_handle(self, handle):
"""Replays a handle obtained with :meth:`get_handle`. Using this function
is much faster than :meth:`playback` for replaying a set of traces repeatedly,
but incurs the overhead of managing the handles onto the programmer."""
(epoch, advance_mu, ptr) = handle
if self.epoch != epoch:
raise DMAError("Invalid handle")
dma_playback(now_mu(), ptr)
delay_mu(advance_mu)