prim: Add arbiter module and testbench

Signed-off-by: Alex Forencich <alex@alexforencich.com>
This commit is contained in:
Alex Forencich
2025-02-28 21:04:49 -08:00
parent 5966d05740
commit 46e60d32f2
3 changed files with 540 additions and 0 deletions

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# SPDX-License-Identifier: CERN-OHL-S-2.0
#
# Copyright (c) 2025 FPGA Ninja, LLC
#
# Authors:
# - Alex Forencich
TOPLEVEL_LANG = verilog
SIM ?= verilator
WAVES ?= 0
COCOTB_HDL_TIMEUNIT = 1ns
COCOTB_HDL_TIMEPRECISION = 1ps
DUT = taxi_arbiter
COCOTB_TEST_MODULES = test_$(DUT)
COCOTB_TOPLEVEL = $(DUT)
MODULE = $(COCOTB_TEST_MODULES)
TOPLEVEL = $(COCOTB_TOPLEVEL)
VERILOG_SOURCES += ../../../rtl/prim/$(DUT).sv
VERILOG_SOURCES += ../../../rtl/prim/taxi_penc.sv
# handle file list files
process_f_file = $(call process_f_files,$(addprefix $(dir $1),$(shell cat $1)))
process_f_files = $(foreach f,$1,$(if $(filter %.f,$f),$(call process_f_file,$f),$f))
uniq_base = $(if $1,$(call uniq_base,$(foreach f,$1,$(if $(filter-out $(notdir $(lastword $1)),$(notdir $f)),$f,))) $(lastword $1))
VERILOG_SOURCES := $(call uniq_base,$(call process_f_files,$(VERILOG_SOURCES)))
# module parameters
export PARAM_PORTS := 32
export PARAM_ARM_ROUND_ROBIN := "1'b1"
export PARAM_ARM_BLOCK := "1'b1"
export PARAM_ARM_BLOCK_ACK := "1'b0"
export PARAM_LSB_HIGH_PRIO := "1'b0"
ifeq ($(SIM), icarus)
PLUSARGS += -fst
COMPILE_ARGS += $(foreach v,$(filter PARAM_%,$(.VARIABLES)),-P $(COCOTB_TOPLEVEL).$(subst PARAM_,,$(v))=$($(v)))
else ifeq ($(SIM), verilator)
COMPILE_ARGS += $(foreach v,$(filter PARAM_%,$(.VARIABLES)),-G$(subst PARAM_,,$(v))=$($(v)))
ifeq ($(WAVES), 1)
COMPILE_ARGS += --trace-fst
VERILATOR_TRACE = 1
endif
endif
include $(shell cocotb-config --makefiles)/Makefile.sim

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#!/usr/bin/env python
# SPDX-License-Identifier: CERN-OHL-S-2.0
"""
Copyright (c) 2020-2025 FPGA Ninja, LLC
Authors:
- Alex Forencich
"""
import logging
import os
import cocotb_test.simulator
import pytest
import cocotb
from cocotb.clock import Clock
from cocotb.triggers import RisingEdge
class TB(object):
def __init__(self, dut):
self.dut = dut
self.log = logging.getLogger("cocotb.tb")
self.log.setLevel(logging.DEBUG)
cocotb.start_soon(Clock(dut.clk, 10, units="ns").start())
dut.req.setimmediatevalue(0)
dut.ack.setimmediatevalue(0)
async def reset(self):
self.dut.rst.setimmediatevalue(0)
await RisingEdge(self.dut.clk)
await RisingEdge(self.dut.clk)
self.dut.rst.value = 1
await RisingEdge(self.dut.clk)
await RisingEdge(self.dut.clk)
self.dut.rst.value = 0
await RisingEdge(self.dut.clk)
await RisingEdge(self.dut.clk)
@cocotb.test()
async def run_single_bit(dut):
tb = TB(dut)
round_robin = bool(int(dut.ARB_ROUND_ROBIN.value))
lsb_high_prio = bool(int(dut.LSB_HIGH_PRIO.value))
await tb.reset()
if lsb_high_prio:
prev_index = 31
else:
prev_index = 0
for i in range(32):
lst = [i]
k = 0
for y in lst:
k = k | 1 << y
tb.log.info("Request: 0x%08x", k)
dut.req.value = k
await RisingEdge(dut.clk)
dut.req.value = 0
await RisingEdge(dut.clk)
if round_robin:
if lsb_high_prio:
# emulate round robin
lst2 = [x for x in lst if x > prev_index]
if len(lst2) == 0:
lst2 = lst
g = min(lst2)
else:
# emulate round robin
lst2 = [x for x in lst if x < prev_index]
if len(lst2) == 0:
lst2 = lst
g = max(lst2)
else:
if lsb_high_prio:
g = min(lst)
else:
g = max(lst)
tb.log.info("Grant (mask): 0x%08x", int(dut.grant.value))
tb.log.info("Grant (index): %d", int(dut.grant_index.value))
assert int(dut.grant.value) == 1 << g
assert int(dut.grant_index.value) == g
prev_index = int(g)
await RisingEdge(dut.clk)
@cocotb.test()
async def run_cycle(dut):
tb = TB(dut)
round_robin = bool(int(dut.ARB_ROUND_ROBIN.value))
lsb_high_prio = bool(int(dut.LSB_HIGH_PRIO.value))
await tb.reset()
if lsb_high_prio:
prev_index = 31
else:
prev_index = 0
for i in range(32):
lst = [0, 5, 10, 15, 20, 25, 30]
k = 0
for y in lst:
k = k | 1 << y
tb.log.info("Request: 0x%08x", k)
dut.req.value = k
await RisingEdge(dut.clk)
dut.req.value = 0
await RisingEdge(dut.clk)
if round_robin:
if lsb_high_prio:
# emulate round robin
lst2 = [x for x in lst if x > prev_index]
if len(lst2) == 0:
lst2 = lst
g = min(lst2)
else:
# emulate round robin
lst2 = [x for x in lst if x < prev_index]
if len(lst2) == 0:
lst2 = lst
g = max(lst2)
else:
if lsb_high_prio:
g = min(lst)
else:
g = max(lst)
tb.log.info("Grant (mask): 0x%08x", int(dut.grant.value))
tb.log.info("Grant (index): %d", int(dut.grant_index.value))
assert int(dut.grant.value) == 1 << g
assert int(dut.grant_index.value) == g
prev_index = int(g)
await RisingEdge(dut.clk)
@cocotb.test()
async def run_two_bits(dut):
tb = TB(dut)
round_robin = bool(int(dut.ARB_ROUND_ROBIN.value))
lsb_high_prio = bool(int(dut.LSB_HIGH_PRIO.value))
await tb.reset()
if lsb_high_prio:
prev_index = 31
else:
prev_index = 0
for i in range(32):
for j in range(32):
lst = [i, j]
k = 0
for y in lst:
k = k | 1 << y
tb.log.info("Request: 0x%08x", k)
dut.req.value = k
await RisingEdge(dut.clk)
dut.req.value = 0
await RisingEdge(dut.clk)
if round_robin:
if lsb_high_prio:
# emulate round robin
lst2 = [x for x in lst if x > prev_index]
if len(lst2) == 0:
lst2 = lst
g = min(lst2)
else:
# emulate round robin
lst2 = [x for x in lst if x < prev_index]
if len(lst2) == 0:
lst2 = lst
g = max(lst2)
else:
if lsb_high_prio:
g = min(lst)
else:
g = max(lst)
tb.log.info("Grant (mask): 0x%08x", int(dut.grant.value))
tb.log.info("Grant (index): %d", int(dut.grant_index.value))
assert int(dut.grant.value) == 1 << g
assert int(dut.grant_index.value) == g
prev_index = int(g)
await RisingEdge(dut.clk)
@cocotb.test()
async def run_five_bits(dut):
tb = TB(dut)
round_robin = bool(int(dut.ARB_ROUND_ROBIN.value))
lsb_high_prio = bool(int(dut.LSB_HIGH_PRIO.value))
await tb.reset()
if lsb_high_prio:
prev_index = 31
else:
prev_index = 0
for i in range(32):
lst = [(i*x) % 32 for x in [1, 3, 5, 7, 11]]
k = 0
for y in lst:
k = k | 1 << y
tb.log.info("Request: 0x%08x", k)
dut.req.value = k
await RisingEdge(dut.clk)
dut.req.value = 0
await RisingEdge(dut.clk)
if round_robin:
if lsb_high_prio:
# emulate round robin
lst2 = [x for x in lst if x > prev_index]
if len(lst2) == 0:
lst2 = lst
g = min(lst2)
else:
# emulate round robin
lst2 = [x for x in lst if x < prev_index]
if len(lst2) == 0:
lst2 = lst
g = max(lst2)
else:
if lsb_high_prio:
g = min(lst)
else:
g = max(lst)
tb.log.info("Grant (mask): 0x%08x", int(dut.grant.value))
tb.log.info("Grant (index): %d", int(dut.grant_index.value))
assert int(dut.grant.value) == 1 << g
assert int(dut.grant_index.value) == g
prev_index = int(g)
await RisingEdge(dut.clk)
# cocotb-test
tests_dir = os.path.abspath(os.path.dirname(__file__))
rtl_dir = os.path.abspath(os.path.join(tests_dir, '..', '..', '..', 'rtl'))
def process_f_files(files):
lst = {}
for f in files:
if f[-2:].lower() == '.f':
with open(f, 'r') as fp:
l = fp.read().split()
for f in process_f_files([os.path.join(os.path.dirname(f), x) for x in l]):
lst[os.path.basename(f)] = f
else:
lst[os.path.basename(f)] = f
return list(lst.values())
@pytest.mark.parametrize("lsb_high_prio", [0, 1])
@pytest.mark.parametrize("round_robin", [0, 1])
def test_taxi_arbiter(request, round_robin, lsb_high_prio):
dut = "taxi_arbiter"
module = os.path.splitext(os.path.basename(__file__))[0]
toplevel = dut
verilog_sources = [
os.path.join(rtl_dir, "prim", f"{dut}.sv"),
os.path.join(rtl_dir, "prim", "taxi_penc.sv"),
]
verilog_sources = process_f_files(verilog_sources)
parameters = {}
parameters['PORTS'] = 32
parameters['ARB_ROUND_ROBIN'] = f"1'b{round_robin}"
parameters['ARB_BLOCK'] = "1'b1"
parameters['ARB_BLOCK_ACK'] = "1'b0"
parameters['LSB_HIGH_PRIO'] = f"1'b{lsb_high_prio}"
extra_env = {f'PARAM_{k}': str(v) for k, v in parameters.items()}
sim_build = os.path.join(tests_dir, "sim_build",
request.node.name.replace('[', '-').replace(']', ''))
cocotb_test.simulator.run(
simulator="verilator",
python_search=[tests_dir],
verilog_sources=verilog_sources,
toplevel=toplevel,
module=module,
parameters=parameters,
sim_build=sim_build,
extra_env=extra_env,
)