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dma: improve/fix documentation

This commit is contained in:
Sebastien Bourdeauducq 2017-03-27 17:21:39 +08:00
parent 2c3f720301
commit b9ff5afc85

View File

@ -1,3 +1,10 @@
"""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 TInt64, TStr, TNone
@ -22,23 +29,28 @@ def dma_playback(timestamp: TInt64, name: TStr) -> TNone:
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):
"""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."""
dma_record_start() # 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):
"""Stops recording a DMA trace. All recorded RTIO operations are stored
in a newly created trace called ``self.name``, and ``now`` is restored
to the value it had before ``__enter__`` was called."""
dma_record_stop(self.name) # see above
at_mu(self.saved_now_mu)