From a0d42a0234fb2dcd1a00884a0b4fbfe8b9f3181d Mon Sep 17 00:00:00 2001
From: jonah <jf3g19@soton.ac.uk>
Date: Sun, 29 Nov 2020 03:47:16 +0000
Subject: [PATCH] added .cpp file for generating LUT
---
generate_LUT.cpp | 67 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)
create mode 100644 generate_LUT.cpp
diff --git a/generate_LUT.cpp b/generate_LUT.cpp
new file mode 100644
index 0000000..bb1fdce
--- /dev/null
+++ b/generate_LUT.cpp
@@ -0,0 +1,67 @@
+#include <iostream>
+#include <bitset>
+#include <functional>
+#include <stdlib.h>
+#include <cmath>
+#include <vector>
+#include <fstream>
+
+/*
+- 1st arg is the propgram name
+- 2nd ... last args are the coefficients of the FIR filter
+*/
+
+int clog2(int n)
+{
+ int a = 0;
+ n--;
+ while (n > 0)
+ {
+ a++;
+ n >>= 1;
+ }
+ return a;
+}
+
+
+int main(int argc, char *argv[])
+{
+ std::size_t num_coeff = argc - 1;
+ std::size_t address_bit_width = num_coeff;
+ std::size_t data_bit_width = num_coeff+8;
+ std::vector<double> coefficients;
+
+ //generate a vector of the coefficients
+ for(std::size_t i = 0; i < num_coeff; ++i)
+ {
+ coefficients.push_back(std::stod(argv[i+1]));
+ }
+
+ std::ofstream dest_file;
+ dest_file.open("LUT_cases.txt", std::ofstream::out | std::ofstream::trunc);
+
+ //for each number in the range 0 ... pow(2,num_coeff-1), multiply each bit by the coefficients
+ //assuming SIGNED 2c multiplication, so num_coeff-1
+ for(std::size_t i = 0; i < pow(2,num_coeff); ++i)
+ {
+ std::bitset<64> bits(i);
+ int sum = 0;
+
+ for(std::size_t j = 0; j < num_coeff; ++j)
+ {
+ sum += bits[j] * coefficients[j];
+ }
+
+ //write the value of the input, i, and the corresponding sum, sum, to a file
+ if(sum >= 0)
+ dest_file << data_bit_width << "'d" << sum << ", ";
+ else
+ dest_file << "-" << data_bit_width << "'d" << abs(sum) << ", ";
+
+ if(!(i%8) && i>0)
+ dest_file << "\n";
+ }
+
+ //add the default case and close the file
+ dest_file.close();
+}
\ No newline at end of file
--
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