From f64cfe2769b6f9001a7770389e47c7be144afaaf Mon Sep 17 00:00:00 2001
From: Kia <kia@special-circumstanc.es>
Date: Wed, 3 Mar 2021 19:29:19 -0700
Subject: [PATCH] split out the flow control component so we can check it
independently
---
gearbox.py | 50 +++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 43 insertions(+), 7 deletions(-)
diff --git a/gearbox.py b/gearbox.py
index 1e679ca..41f4928 100755
--- a/gearbox.py
+++ b/gearbox.py
@@ -3,13 +3,22 @@ from nmigen import *
from nmigen.hdl.rec import *
from nmigen.cli import main
+
+
+# REMAINING WORK
+#
+# make a quick-and-dirty testbench that selects a random inwidth, random outwidth, and randomly
+# starts/stops the input/output and verifies that the sequence of bits coming out is the same
+# as that coming in (can do with PRBS) and that bus interface constraints are not violated
+
+
class IndexDisambiguator(Enum):
LAST_OP_UNKNOWN = 0
LAST_OP_WAS_WRITE = 1
LAST_OP_WAS_READ = 2
class GearboxBusLayout(Layout):
- def __init__(self, *, in_width, out_width):
+ def __init__(self, *, in_width, out_width): # the * forces keyword args
super().__init__([
# DATA
("data_in", unsigned(in_width)), # FROM SOURCE
@@ -30,11 +39,41 @@ class GearboxBus(Record):
super().__init__(GearboxBusLayout(in_width=in_width, out_width=out_width))
-class GearboxFlow(Elaboratable):
- def __init__(self):
+
+class GearboxFCLayout(Layout):
+ def __init__(self, *, len_storage):
+ super().__init__([
+ # DATA
+ ("read_ptr", unsigned(range(len_storage))), # FROM GEARBOX
+ ("write_ptr", unsigned(range(len_storage))), # FROM GEARBOX
+
+ # CONTROL
+ ("write_happens_this_cycle", 1), # TO GEARBOX
+ ("read_happens_this_cycle", 1), # TO GEARBOX
+
+ ("ready_in", 1), # FROM GEARBOX (FROM DOWNSTREAM)
+ ("valid_in", 1), # FROM GEARBOX (FROM UPSTREAM)
+
+
+ ])
+
+class GearboxFCBus(Record):
+ def __init__(self, *, len_storage):
+ super().__init__(GearboxFCLayout(len_storage=len_storage))
+
+
+
+class GearboxFlowControl(Elaboratable):
+ def __init__(self, *, in_width, out_width, len_storage):
+ self.in_width = in_width
+ self.out_width = out_width
+ self.len_storage = len_storage
+
+ self.bus = GearboxBus(len_storage=len_storage)
+
def elaborate(self, platform):
- # The top-level flow control logic works as follows.
+ # The top-level flow control logic works as follows.
# First, we determine which operations are *possible* based on the read/write indices
# and the index disambiguator bit:
@@ -90,9 +129,6 @@ class GearboxFlow(Elaboratable):
-
-
-
class ArbitraryGearbox(Elaboratable):
def __init__(self, *, in_width, out_width):
self.in_width = in_width
--
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