BlifUtils is a library to handle BLIF netlists in Ruby. The Berkeley Logic Interchange Format (BLIF) allows to describe logic-level hierarchical circuits in textual form. Its specification can be found here. The BLIF format is used by programs such as ABC (logic synthesis) or VPR (placement and routing).
BlifUtils can read and write BLIF files, elaborate internal representations of the netlists, analyze it, flattent modules, write the modules as VHDL entities, and generate C++ code for fast netlist simulation.
To install BlifUtils from the git repository:
$ git clone https://github.com/TheotimeBollengier/blifutils
$ cd blifutils
$ gem build blifutils.gemspec
$ gem install blifutils.<version>.gem
Alternatively, the blifutils gem is also hosted on RubyGems (https://rubygems.org/gems/blifutils). So you can simply type:
$ gem install blifutils
BlifUtils uses the RLTK gem (https://github.com/chriswailes/RLTK).
require 'blifutils'
## Parse input file and sub-referenced files ##
netlist = BlifUtils::read('sqrt8.blif')
netlist.models.collect { |model| model.name }
#=> ["sqrt8",
# "sqrt8_PO",
# "sqrt8_PO_output",
# "sqrt8_PO_sqrtr",
# "sqrt8_PO_work",
# "sqrt8_PC",
# "sqrt8_PC_done",
# "sqrt8_PC_state",
# "sqrt8_PC_counter"]
puts netlist.get_model_by_name('sqrt8_PC').analyze
#=> "+----------------------------------------+
# | Model "sqrt8_PC" analysis |
# +----------------------------------------+
# Model "sqrt8_PC"
# Inputs: 2
# Outputs: 3
# Nets: 7
# Edges: 13
# Nodes: 3
# Latches: 0
# Logic gates: 0
# Sub circuits: 3
# Sub circuits repartition:
# sqrt8_PC_done: 1
# sqrt8_PC_state: 1
# sqrt8_PC_counter: 1"
sqrt8pc_flattened_model = netlist.flatten('sqrt8_PC')
sqrt8pc_flattened_model.analyze
#=> "+----------------------------------------+
# | Model "sqrt8_PC" analysis |
# +----------------------------------------+
# Model "sqrt8_PC"
# Inputs: 2
# Outputs: 3
# Nets: 21
# Edges: 38
# Nodes: 19
# Latches: 5
# Logic gates: 14
# Sub circuits: 0
# Gates repartition:
# 1 input: 7 50.0%
# 2 inputs: 3 21.4%
# 4 inputs: 3 21.4%
# 5 inputs: 1 7.1%
# Buffers: 3"
## Analyze the logic level of the module
## that is to say the maximum number of logic functions between two latches or IOs.
sqrt8pc_flattened_model.level #=> 4
sqrt8pc_flattened_model.to_blif
#=> ".model sqrt8_PC
# .inputs _clk_ go[0]
# .outputs done[0] state[1] state[0]
# .latch n1 n0 re _clk_ 0
# .latch n6 n2 re _clk_ 0
# .latch n7 n3 re _clk_ 0
# .latch nD nA re _clk_ 0
# .latch nE nB re _clk_ 0
# .names n2 n3 n1
# 11 1
# .names n8 n9 n4
# 1- 1
# -1 1
# .names n4 n5
# 0 1
# .names go[0] n2 n3 n2 n6
# 10-- 1
# -01- 1
# 0001 1
# .names go[0] n2 n3 n5 n3 n7
# -10-- 1
# -011- 1
# 000-1 1
# .names nA n8
# 0 1
# .names nB n9
# 0 1
# .names nB nA nC
# 10 1
# 01 1
# .names n2 n3 nA nF nD
# 1-1- 1
# 01-1 1
# .names n2 n3 nB nC nE
# 1-1- 1
# 01-1 1
# .names nA nF
# 0 1
# .names n0 done[0]
# 1 1
# .names n3 state[1]
# 1 1
# .names n2 state[0]
# 1 1
# .end"
sqrt8pc_flattened_model.to_vhdl
#=> "library IEEE;
# use IEEE.STD_LOGIC_1164.ALL;
#
#
# entity SQRT8_PC is
# port ( clk_in : in std_ulogic;
# go_0_in : in std_ulogic;
# done_0_out : out std_ulogic;
# state_1_out : out std_ulogic;
# state_0_out : out std_ulogic);
# end SQRT8_PC;
#
#
# architecture blif of SQRT8_PC is
#
# signal clk : std_ulogic;
# signal go_0 : std_ulogic;
# signal n0 : std_ulogic := '0';
# signal n1 : std_ulogic;
# signal n2 : std_ulogic := '0';
# signal n3 : std_ulogic := '0';
# signal n4 : std_ulogic;
# signal n5 : std_ulogic;
# signal n6 : std_ulogic;
# signal n7 : std_ulogic;
# signal n8 : std_ulogic;
# signal n9 : std_ulogic;
# signal nA : std_ulogic := '0';
# signal nB : std_ulogic := '0';
# signal nC : std_ulogic;
# signal nD : std_ulogic;
# signal nE : std_ulogic;
# signal nF : std_ulogic;
# signal done_0 : std_ulogic;
# signal state_1 : std_ulogic;
# signal state_0 : std_ulogic;
#
# begin
#
# clk <= clk_in;
# go_0 <= go_0_in;
#
# done_0_out <= done_0;
# state_1_out <= state_1;
# state_0_out <= state_0;
#
#
# process(clk)
# begin
# if rising_edge(clk) then
# n0 <= n1;
# n2 <= n6;
# n3 <= n7;
# nA <= nD;
# nB <= nE;
# end if;
# end process;
#
# n1 <= (n2 and n3);
# n4 <= (n8) or
# (n9);
# n5 <= (not(n4));
# n6 <= (go_0 and not(n2)) or
# (not(n2) and n3) or
# (not(go_0) and not(n2) and not(n3) and n2);
# n7 <= (n2 and not(n3)) or
# (not(n2) and n3 and n5) or
# (not(go_0) and not(n2) and not(n3) and n3);
# n8 <= (not(nA));
# n9 <= (not(nB));
# nC <= (nB and not(nA)) or
# (not(nB) and nA);
# nD <= (n2 and nA) or
# (not(n2) and n3 and nF);
# nE <= (n2 and nB) or
# (not(n2) and n3 and nC);
# nF <= (not(nA));
# done_0 <= (n0);
# state_1 <= (n3);
# state_0 <= (n2);
#
# end blif;
netlist.create_simulation_file_for_model('sqrt8')
# Creates files sqrt8_cpp_header.hh sqrt8_cpp_sim.cc
# and compiles to sqrt8_cpp_sim.o You can then write a C++ testbench:
#include <cmath>
#include "sqrt8_cpp_header.hh"
int main(void)
{
uint64_t in, out, golden;
Sqrt8SimulationClass *dut = new Sqrt8SimulationClass();
dut->reset();
for (in = 0; in < 256; in++) {
iterations++;
dut->INPUT_VECTOR_radicand->setValue(in);
dut->INPUT_NET_go->setValue(1);
dut->cycle();
dut->INPUT_NET_go->setValue(0);
dut->cycle();
while (dut->OUTPUT_NET_done->getValue() != 1) {
dut->propagate();
dut->clock();
dut->propagate();
// equivalent to 'dut->cycle()'
}
out = dut->OUTPUT_VECTOR_squareRoot->getValue(NULL);
golden = (int)sqrt(in);
if (out != golden) {
std::cerr << "sqrt(" << in << ") => " << out << " (should be " << golden << ")" << std::endl;
}
}
delete dut;
return 0;
}Compile and execute this testbench:
$ g++ -W -Wall -I. -o simu testbench.cc sqrt8_cpp_sim.o
$ ./simu
The examples/zpu/ directory contains the necessary files to simulate
a ZPU ZPU processor https://github.com/zylin/zpu
executing a hello-world.
$ cd examples/zpu
$ ruby simulate_zpu.rb
Parsing file "zpu_mem16.blif"...
Elaborating model "zpu_mem16"...
WARNING: In model "zpu_mem16": net "_clk_" has no fanouts
------------------------------------------------------------
Model collection contains 1 models
+----------------------------------------+
| Model "zpu_mem16" analysis |
+----------------------------------------+
Model "zpu_mem16"
Inputs: 34
Outputs: 50
Nets: 1006
Edges: 4039
Nodes: 972
Latches: 156
Logic gates: 816
Sub circuits: 0
Gates repartition:
1 input: 51 6.3%
2 inputs: 33 4.0%
3 inputs: 95 11.6%
4 inputs: 108 13.2%
5 inputs: 175 21.4%
6 inputs: 354 43.4%
Buffers: 51
------------------------------------------------------------
Generating graph from model components...
Extracting connected subgraphs... 87 subgraphs found
Checking that there are no cycles in subgraphs... Ok
Layering subgraphs...
Maximum number of layers: 33
Writing static schedule for component simulation...
Written C++ simulation model in file "zpu_mem16_cpp_sim.cc"
Compiling model...
g++ -c -W -Wall -O3 -std=c++11 zpu_mem16_cpp_sim.cc -o zpu_mem16_cpp_sim.o
Written C++ model simulation header in file "zpu_mem16_cpp_header.hh"
Now you can write your testbench in a C++ file as 'testbench.cc' including '#include "zpu_mem16_cpp_header.hh"', then run:
g++ -W -Wall -O3 zpu_mem16_cpp_sim.o testbench.cc
-- Compiling testbench -------------------------------------
Executing: g++ -W -Wall -I. -o zpu_simulation testbench_zpu.cc zpu_mem16_cpp_sim.o
You can now execute the testbench with "./zpu_simulation <zpu_compiled_program>"
-- Executing simulation ------------------------------------
Executing: ./zpu_simulation zpu_helloworld.bin
Read 3284 bytes from file 'zpu_helloworld.bin' (memory filled 10.0%)
Starting simulation
Hello, world!
What you see is a processor simulated at a logic netlist level, executing a helloworld.
Simulation ended
80877 clock cycles in 1.271 s
Simulation average clock speed: 63637 Hzxecutable
To use BlifUtils directly from a terminal or a Makefile,
this gem also include the blifutils executable script, which uses command line arguments.
$ blifutils --help
Usage: blifutils [options] -i file1 file2 ...
-i, --input FILES Input BLIF files
-o, --output [FILE] Output BLIF FILE
-p, --print-models Print model names
-m, --model NAME Name of the model to process
-f, --flatten Flatten the model hierarchy in a single model
-s, --simulation [FILE] Create C++ simulation files
-v, --vhdl Create a vhdl file
-a, --analyze [level] Print analysis, with optional level analysis (level)
-A, --analyze_with_graphviz Print analysis, with level analysis, wirting graphvis files
--default-latch-type TYPE Set undefined latch types to TYPE (re: rising edge, fe: falling edge, al: active low, ah: active high, as: asynchronous)
--default-latch-clock NAME Set undefined latch contol signals to NAME
--default-latch-initial-value VALUE
Set undefined latch initial value to VALUE (0, 1, 2: don't care, 3: undefine)
-q, --quiet Don't print messages
-h, --help Display this help