Refactor frequency analysis

ex03/main.c

@@ -1,33 +1,9 @@
 #include "utils.h"
 #include <ctype.h>
-#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-
+#include <math.h>
-double frequency_score(unsigned char *buf, size_t len) {
-  static const double english_freqs[26] = {
-      0.08167, 0.01492, 0.02782, 0.04253, 0.12702, 0.02228, 0.02015, // A-G
-      0.06094, 0.06966, 0.00153, 0.00772, 0.04025, 0.02406, 0.06749, // H-N
-      0.07507, 0.01929, 0.00095, 0.05987, 0.06327, 0.09056, 0.02758, // O-U
-      0.00978, 0.02360, 0.00150, 0.01974, 0.00074                    // V-Z
-  };
-
-  unsigned int counts[26] = {0};
-  for (size_t i = 0; i < len; ++i) {
-    unsigned char c = tolower(buf[i]) - 'a';
-    if (c < 26) {
-      counts[c]++;
-    }
-  }
-
-  double chi2 = 0;
-  for (size_t i = 0; i < 26; ++i) {
-    double expected = len * english_freqs[i];
-    chi2 += pow(counts[i] - expected, 2) / expected;
-  }
-  return chi2;
-}
 
 int main(int argc, char *argv[]) {
   if (argc < 2) {

meson.build

@@ -3,6 +3,6 @@ project('cryptopals', 'c')
 cc = meson.get_compiler('c')
 m_dep = cc.find_library('m', required : false)
 
-executable('ex01', ['ex01/main.c', 'utils.c'])
+executable('ex01', ['ex01/main.c', 'utils.c'], dependencies: m_dep)
-executable('ex02', ['ex02/main.c', 'utils.c'])
+executable('ex02', ['ex02/main.c', 'utils.c'], dependencies: m_dep)
 executable('ex03', ['ex03/main.c', 'utils.c'], dependencies: m_dep)

utils.c

@@ -1,5 +1,6 @@
 #include "utils.h"
 #include <ctype.h>
+#include <math.h>
 #include <string.h>
 
 unsigned char hex_to_byte(const char c) {
@@ -35,3 +36,27 @@ unsigned char *bytes_to_base64(unsigned char *out,
   }
   return out;
 }
+
+double frequency_score(unsigned char *buf, size_t len) {
+  static const double english_freqs[26] = {
+      0.08167, 0.01492, 0.02782, 0.04253, 0.12702, 0.02228, 0.02015, // A-G
+      0.06094, 0.06966, 0.00153, 0.00772, 0.04025, 0.02406, 0.06749, // H-N
+      0.07507, 0.01929, 0.00095, 0.05987, 0.06327, 0.09056, 0.02758, // O-U
+      0.00978, 0.02360, 0.00150, 0.01974, 0.00074                    // V-Z
+  };
+
+  unsigned int counts[26] = {0};
+  for (size_t i = 0; i < len; ++i) {
+    unsigned char c = tolower(buf[i]) - 'a';
+    if (c < 26) {
+      counts[c]++;
+    }
+  }
+
+  double chi2 = 0;
+  for (size_t i = 0; i < 26; ++i) {
+    double expected = len * english_freqs[i];
+    chi2 += pow(counts[i] - expected, 2) / expected;
+  }
+  return chi2;
+}

utils.h

@@ -7,5 +7,6 @@ unsigned char hex_to_byte(const char c);
 size_t hex_to_bytes(unsigned char *out, const char hex[static 1]);
 unsigned char *bytes_to_base64(unsigned char *out,
                                const unsigned char in[static 1], size_t len);
+double frequency_score(unsigned char *buf, size_t len);
 
 #endif /* UTILS_H */