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soc/rtio: software-controlled replace

This commit is contained in:
Sebastien Bourdeauducq 2014-09-11 23:09:20 +08:00
parent 800096f9a0
commit 202284d44c
1 changed files with 7 additions and 18 deletions

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@ -13,6 +13,7 @@ class _RTIOBankO(Module):
self.value = Signal(2)
self.writable = Signal()
self.we = Signal()
self.replace = Signal()
self.underflow = Signal()
self.level = Signal(bits_for(fifo_depth))
@ -22,23 +23,9 @@ class _RTIOBankO(Module):
counter = Signal(counter_width, reset=counter_init)
self.sync += counter.eq(counter + 1)
# ignore series of writes with the same value
we_filtered = Signal()
prev_value = Signal(2)
self.comb += we_filtered.eq(self.we & (self.value != prev_value))
self.sync += If(self.we & self.writable, prev_value.eq(self.value))
# collapse zero-length intervals
replace = Signal()
prev_ts_coarse = Signal(counter_width)
self.sync += If(we_filtered & self.writable,
prev_ts_coarse.eq(self.timestamp[fine_ts_width:]))
self.comb += replace.eq(
self.timestamp[fine_ts_width:] == prev_ts_coarse)
# detect underflows
self.sync += \
If(we_filtered & self.writable,
If((self.we & self.writable) | self.replace,
If(self.timestamp[fine_ts_width:] < counter + 2,
self.underflow.eq(1))
)
@ -51,12 +38,12 @@ class _RTIOBankO(Module):
self.submodules += fifo
fifos.append(fifo)
# FIFO write
# FIFO replace/write
self.comb += [
fifo.din.timestamp.eq(self.timestamp),
fifo.din.value.eq(self.value),
fifo.we.eq(we_filtered & (self.sel == n)),
fifo.replace.eq(replace)
fifo.we.eq((self.we | self.replace) & (self.sel == n)),
fifo.replace.eq(self.replace)
]
# FIFO read
@ -174,6 +161,7 @@ class RTIO(Module, AutoCSR):
self._r_o_value = CSRStorage(2)
self._r_o_writable = CSRStatus()
self._r_o_we = CSR()
self._r_o_replace = CSR()
self._r_o_error = CSRStatus(2)
self._r_o_level = CSRStatus(bits_for(ofifo_depth))
@ -204,6 +192,7 @@ class RTIO(Module, AutoCSR):
self.bank_o.value.eq(self._r_o_value.storage),
self._r_o_writable.status.eq(self.bank_o.writable),
self.bank_o.we.eq(self._r_o_we.re),
self.bank_o.replace.eq(self._r_o_replace.re),
self._r_o_error.status.eq(self.bank_o.underflow),
self._r_o_level.status.eq(self.bank_o.level)
]