wishbone/sram/burst: First review/Minor cleanups.
This commit is contained in:
parent
9c4778b2c1
commit
ceb25445d2
|
@ -361,10 +361,13 @@ class SRAM(Module):
|
|||
else:
|
||||
read_only = False
|
||||
|
||||
###
|
||||
# # #
|
||||
|
||||
adr_burst = Signal()
|
||||
|
||||
# Burst support.
|
||||
# --------------
|
||||
|
||||
if self.bus.bursting:
|
||||
adr_wrap_mask = Array((0b0000, 0b0011, 0b0111, 0b1111))
|
||||
adr_wrap_max = adr_wrap_mask[-1].bit_length()
|
||||
|
@ -380,7 +383,7 @@ class SRAM(Module):
|
|||
|
||||
adr_next = Signal(len(self.bus.adr))
|
||||
|
||||
# only incrementing burst cycles are supported
|
||||
# Only Incrementing Burts are supported.
|
||||
self.comb += [
|
||||
Case(self.bus.cti, {
|
||||
# incrementing address burst cycle
|
||||
|
@ -398,19 +401,18 @@ class SRAM(Module):
|
|||
)
|
||||
]
|
||||
|
||||
# latch initial address - initial address without wrapping bits and wrap offset
|
||||
# Latch initial address (without wrapping bits and wrap offset).
|
||||
self.sync += [
|
||||
If(self.bus.cyc & self.bus.stb & adr_burst,
|
||||
adr_latched.eq(1),
|
||||
# latch initial address, then increment it every clock cycle
|
||||
# Latch initial address, then increment it every clock cycle
|
||||
If(adr_latched,
|
||||
adr_counter.eq(adr_counter + 1)
|
||||
).Else(
|
||||
adr_counter_offset.eq(self.bus.adr & adr_wrap_mask[self.bus.bte]),
|
||||
adr_counter.eq(adr_counter_base + Cat(~self.bus.we,
|
||||
Replicate(0, len(adr_counter)-1)
|
||||
)
|
||||
)
|
||||
adr_counter.eq(adr_counter_base +
|
||||
Cat(~self.bus.we, Replicate(0, len(adr_counter)-1))
|
||||
)
|
||||
),
|
||||
If(self.bus.cti == CTI_BURST_END,
|
||||
adr_latched.eq(0),
|
||||
|
@ -424,28 +426,25 @@ class SRAM(Module):
|
|||
),
|
||||
]
|
||||
|
||||
# next address = sum of counter value without wrapped bits
|
||||
# and wrapped counter bits with offset
|
||||
# Next Address = counter value without wrapped bits + wrapped counter bits with offset.
|
||||
self.comb += [
|
||||
adr_offset_lsb.eq((adr_counter + adr_counter_offset) & adr_wrap_mask[self.bus.bte]),
|
||||
adr_offset_msb.eq(adr_counter & ~adr_wrap_mask[self.bus.bte]),
|
||||
adr_next.eq(adr_offset_msb + adr_offset_lsb)
|
||||
]
|
||||
|
||||
else: # self.ram.bursting == False
|
||||
self.comb += adr_burst.eq(0)
|
||||
# # #
|
||||
|
||||
###
|
||||
|
||||
# memory
|
||||
# Memory.
|
||||
# -------
|
||||
port = self.mem.get_port(write_capable=not read_only, we_granularity=8,
|
||||
mode=READ_FIRST if read_only else WRITE_FIRST)
|
||||
self.specials += self.mem, port
|
||||
# generate write enable signal
|
||||
# Generate write enable signal
|
||||
if not read_only:
|
||||
self.comb += [port.we[i].eq(self.bus.cyc & self.bus.stb & self.bus.we & self.bus.sel[i])
|
||||
for i in range(bus_data_width//8)]
|
||||
# address and data
|
||||
# Address and data
|
||||
self.comb += port.adr.eq(self.bus.adr[:len(port.adr)])
|
||||
if self.bus.bursting:
|
||||
self.comb += If(adr_burst & adr_latched,
|
||||
|
@ -457,7 +456,7 @@ class SRAM(Module):
|
|||
if not read_only:
|
||||
self.comb += port.dat_w.eq(self.bus.dat_w),
|
||||
|
||||
# generate ack
|
||||
# Generate Ack.
|
||||
self.sync += [
|
||||
self.bus.ack.eq(0),
|
||||
If(self.bus.cyc & self.bus.stb & (~self.bus.ack | adr_burst), self.bus.ack.eq(1))
|
||||
|
|
Loading…
Reference in New Issue