Add graph plotting for dudect analysis

Implement graph generation using "gnuplot" for dudect to visualize
t-statistic measurements.

- Add "plot.c" and "plot.h" files to support graphing, "plot.c"
  stores each measurements execution time in "data_buffer". When
  plot_graph() is called, stores the data to file and generates
  a "gnuplot" script. I try to replicate the graph shown in "dudect's"
  paper "Dude, is my code constant time?".

- Modify "fixture.c" to integrate with new plotting functionality.

- Move definition of ENOUGH_MEASURE and TEST_TRIES from "fixture.c" to
  "fixture.h" for "plot.c" to access and specify size of "data_buffer"

- Update "Makefile" to include plot.o in build

This enhancement allows visual representation of constant-time
analysis results, making it easier to interpret dudect test outcomes.

Change-Id: I94387b44010e4b410475c346864d784bdb75251d

Author: SimonLiu423

.gitignore

@@ -25,3 +25,8 @@ GPATH
 GRTAGS
 GSYMS
 GTAGS
+
+# gnuplot files
+gnuplot_script.gnu
+data.txt
+*.png

Makefile

@@ -38,7 +38,7 @@ $(GIT_HOOKS):
 	@echo
 
 OBJS := qtest.o report.o console.o harness.o queue.o \
-        random.o dudect/constant.o dudect/fixture.o dudect/ttest.o \
+        random.o dudect/constant.o dudect/fixture.o dudect/ttest.o dudect/plot.o \
         shannon_entropy.o \
         linenoise.o web.o
 

dudect/fixture.c

@@ -38,11 +38,9 @@
 
 #include "constant.h"
 #include "fixture.h"
+#include "plot.h"
 #include "ttest.h"
 
-#define ENOUGH_MEASURE 10000
-#define TEST_TRIES 10
-
 static t_context_t *t;
 
 /* threshold values for Welch's t-test */
@@ -83,6 +81,8 @@ static bool report(void)
     double number_traces_max_t = t->n[0] + t->n[1];
     double max_tau = max_t / sqrt(number_traces_max_t);
 
+    add_data(max_t);
+
     printf("\033[A\033[2K");
     printf("meas: %7.2lf M, ", (number_traces_max_t / 1e6));
     if (number_traces_max_t < ENOUGH_MEASURE) {
@@ -156,16 +156,19 @@ static bool test_const(char *text, int mode)
     bool result = false;
     t = malloc(sizeof(t_context_t));
 
+    init_data_buffer();
     for (int cnt = 0; cnt < TEST_TRIES; ++cnt) {
         printf("Testing %s...(%d/%d)\n\n", text, cnt, TEST_TRIES);
         init_once();
         for (int i = 0; i < ENOUGH_MEASURE / (N_MEASURES - DROP_SIZE * 2) + 1;
              ++i)
             result = doit(mode);
         printf("\033[A\033[2K\033[A\033[2K");
+        next_try();
         if (result)
             break;
     }
+    plot_graph(t_threshold_moderate, text);
     free(t);
     return result;
 }

dudect/fixture.h

@@ -4,6 +4,9 @@
 #include <stdbool.h>
 #include "constant.h"
 
+#define ENOUGH_MEASURE 10000
+#define TEST_TRIES 10
+
 /* Interface to test if function is constant */
 #define _(x) bool is_##x##_const(void);
 DUT_FUNCS

dudect/plot.c

@@ -0,0 +1,131 @@
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "fixture.h"
+
+#define GNUPLOT_SCRIPT "gnuplot_script.gnu"
+#define DATA_FILE "data.txt"
+
+int n_tries = 0;
+
+struct {
+    double y[ENOUGH_MEASURE];
+    int n_measures;
+} data_buffer[TEST_TRIES];
+
+static double max_data_value()
+{
+    double mx = 0;
+    for (int i = 0; i < TEST_TRIES; i++) {
+        double value = data_buffer[i].y[data_buffer[i].n_measures - 1];
+        if (value > mx)
+            mx = value;
+    }
+    return mx;
+}
+
+void init_data_buffer()
+{
+    n_tries = 0;
+    for (int i = 0; i < TEST_TRIES; i++) {
+        data_buffer[i].n_measures = 0;
+    }
+}
+
+void next_try()
+{
+    n_tries++;
+}
+
+void add_data(double y)
+{
+    if (n_tries >= TEST_TRIES) {
+        fprintf(stderr, "Buffer overflow\n");
+        exit(1);
+    }
+    data_buffer[n_tries].y[data_buffer[n_tries].n_measures++] = y;
+}
+
+void save_data()
+{
+    FILE *fp = fopen(DATA_FILE, "w");
+    if (!fp) {
+        perror("Error opening file");
+        exit(1);
+    }
+    fprintf(fp, "# X ");
+    for (int i = 0; i < TEST_TRIES; i++) {
+        fprintf(fp, "t%d ", i);
+    }
+    fprintf(fp, "\n");
+    for (int i = 0; i < data_buffer[0].n_measures; i++) {
+        fprintf(fp, "%d ", (int) i);
+        for (int j = 0; j < TEST_TRIES; j++) {
+            fprintf(fp, "%lf ", data_buffer[j].y[i]);
+        }
+        fprintf(fp, "\n");
+    }
+    fclose(fp);
+}
+
+void generate_gnuplot_script(double threshold,
+                             const char *title,
+                             const char *output_file)
+{
+    FILE *gp = fopen(GNUPLOT_SCRIPT, "w");
+    if (!gp) {
+        perror("Error opening Gnuplot script file");
+        exit(1);
+    }
+
+    int mx_val = (int) max_data_value();
+    int y_range = mx_val < 25 ? 50 : mx_val * 2;
+
+
+    fprintf(gp,
+            "set terminal pngcairo enhanced size 800,400\n"
+            "set output '%s'\n"
+            "set title '%s'\n"
+            "set xlabel '# measurements'\n"
+            "set ylabel '|t| statistic'\n"
+            "set grid front\n"
+            "set xrange [0:%d]\n"
+            "set yrange [0:%d]\n"
+
+            // #Define the threshold as a function
+            "f(x) = %lf\n"
+
+            // #Fill the lower part(green) and upper part(red)
+            "set style fill solid 0.3\n"
+            "plot '%s' using 1:(f($1)) with filledcurves y1=0 lc rgb 'green' "
+            "notitle, \\\n"
+            "     '%s' using 1:(f($1)) with filledcurves y1=%d lc rgb 'red' "
+            "notitle, \\\n"
+            "     for [i=2:%d] '%s' using 1:i:(i) with lines lw 2 lc variable "
+            "title sprintf('Test %%d', i-1)\n",
+            output_file, title, data_buffer[0].n_measures, y_range, threshold,
+            DATA_FILE, DATA_FILE, y_range, n_tries + 1, DATA_FILE);
+
+    fclose(gp);
+}
+
+void plot_graph(double threshold, const char *title)
+{
+    save_data();
+    char *output_file = malloc(strlen(title) + 5);
+    if (!output_file) {
+        perror("Error allocating memory");
+        exit(1);
+    }
+    strncpy(output_file, title, strlen(title) + 1);
+    strcat(output_file, ".png");
+    generate_gnuplot_script(threshold, title, output_file);
+    int ret = system("gnuplot " GNUPLOT_SCRIPT);
+    if (ret != 0) {
+        fprintf(stderr, "Error generating graph\n");
+        exit(1);
+    }
+    printf("Graph generated: %s\n", output_file);
+    free(output_file);
+}

dudect/plot.h

@@ -0,0 +1,8 @@
+#ifndef DUDECT_PLOT_H
+#define DUDECT_PLOT_H
+
+void init_data_buffer();
+void next_try();
+void add_data(double y);
+void plot_graph(double threshold, char *title);
+#endif