Use array notation for pointer parameters

src/ex03/main.c

@@ -23,7 +23,7 @@ int main(int argc, char *argv[]) {
     for (size_t i = 0; i < len; ++i) {
       cur[i] = buf[i] ^ c;
     }
-    double score = frequency_score(cur, len);
+    double score = frequency_score(len, cur);
     if (score < min_score) {
       min_score = score;
       key = c;

src/ex04/main.c

@@ -36,7 +36,7 @@ int main(int argc, char *argv[]) {
       for (size_t i = 0; i < len; ++i) {
         cur[i] = buf[i] ^ c;
       }
-      double score = frequency_score(cur, len);
+      double score = frequency_score(len, cur);
       if (score < 40.0) {
         printf("%4u | %c   | %5.1f | ", line_count, c,
                score);

src/ex06/main.c

@@ -6,8 +6,8 @@
 
 #define BUF_SIZE 4096
 
-double normalized_edit_distance(const unsigned char *buf,
+double normalized_edit_distance(unsigned int keysize,
-                                unsigned int keysize) {
+                                const unsigned char buf[static keysize * 4]) {
   char block1[keysize];
   char block2[keysize];
   char block3[keysize];
@@ -58,7 +58,7 @@ int main(int argc, char *argv[]) {
   unsigned int keysize = 40;
   double min_edit_dist = INFINITY;
   for (unsigned int i = 40; i > 1; --i) {
-    double edit_dist = normalized_edit_distance(buf, i);
+    double edit_dist = normalized_edit_distance(i, buf);
     if (edit_dist < min_edit_dist) {
       min_edit_dist = edit_dist;
       keysize = i;

src/utils.c

@@ -24,7 +24,7 @@ unsigned char hex_to_byte(const char c) {
   return 10 + c - 'a';
 }
 
-size_t hex_to_bytes(unsigned char *out, const char hex[static 1]) {
+size_t hex_to_bytes(unsigned char out[static 1], const char hex[static 1]) {
   for (size_t i = 0; i < strlen(hex); ++i) {
     char c = tolower(hex[i]);
     unsigned char value = hex_to_byte(c);
@@ -39,7 +39,7 @@ size_t hex_to_bytes(unsigned char *out, const char hex[static 1]) {
 static const char base64_table[65] =
     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
-char *bytes_to_base64(char *out, const unsigned char in[static 1], size_t len) {
+char *bytes_to_base64(char out[static 4], const unsigned char in[static 3], size_t len) {
   for (size_t i = 0; i < len - 2; i += 3) {
     size_t j = i / 3 * 4;
     out[j] = base64_table[in[i] >> 2];
@@ -50,7 +50,7 @@ char *bytes_to_base64(char *out, const unsigned char in[static 1], size_t len) {
   return out;
 }
 
-size_t base64_to_bytes(unsigned char *out, const char *in) {
+size_t base64_to_bytes(unsigned char out[static 3], const char in[static 4]) {
   char decoding_table[256] = {0};
   for (size_t i = 0; i < 64; ++i) {
     decoding_table[(unsigned char)base64_table[i]] = i;
@@ -86,7 +86,7 @@ size_t base64_to_bytes(unsigned char *out, const char *in) {
   return i;
 }
 
-double frequency_score(const char *buf, size_t len) {
+double frequency_score(size_t len, const char buf[static len]) {
   static const double english_freqs[27] = {
       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
@@ -119,7 +119,7 @@ double frequency_score(const char *buf, size_t len) {
   return chi2;
 }
 
-unsigned int hamming(const char *s1, const char *s2) {
+unsigned int hamming(const char s1[static 1], const char s2[static 1]) {
   unsigned int len1 = strlen(s1);
   unsigned int len2 = strlen(s2);
 

src/utils.h

@@ -4,10 +4,10 @@
 #include <stdlib.h>
 
 unsigned char hex_to_byte(const char c);
-size_t hex_to_bytes(unsigned char *out, const char hex[static 1]);
+size_t hex_to_bytes(unsigned char out[static 1], const char hex[static 1]);
-char *bytes_to_base64(char *out, const unsigned char in[static 1], size_t len);
+char *bytes_to_base64(char out[static 4], const unsigned char in[static 3], size_t len);
-size_t base64_to_bytes(unsigned char *out, const char *in);
+size_t base64_to_bytes(unsigned char out[static 3], const char in[static 4]);
-double frequency_score(const char *buf, size_t len);
+double frequency_score(size_t len, const char buf[static len]);
-unsigned int hamming(const char *s1, const char *s2);
+unsigned int hamming(const char s1[static 1], const char s2[static 1]);
 
 #endif /* UTILS_H */

tests/main.c

@@ -63,18 +63,18 @@ static MunitResult test_frequency_score(const MunitParameter params[],
   (void)data;
 
   // Non-printable characters should return INFINITY.
-  assert(isfinite(frequency_score("YELLOW SUBMARINE", 16)));
+  assert(isfinite(frequency_score(16, "YELLOW SUBMARINE")));
-  assert(isinf(frequency_score("\0x07", 1)));
+  assert(isinf(frequency_score(1, "\0x07")));
-  assert(isinf(frequency_score("YELLOW\0x07 SUBMARINE", 17)));
+  assert(isinf(frequency_score(17, "YELLOW\0x07 SUBMARINE")));
 
   // Teh frequency score should be case-insensitive.
-  assert_double_equal(frequency_score("YELLOW SUBMARINE", 16),
+  assert_double_equal(frequency_score(16, "YELLOW SUBMARINE"),
-                      frequency_score("yellow submarine", 16), 12);
+                      frequency_score(16, "yellow submarine"), 12);
 
   // E is more frequent than Z.
-  assert_double(frequency_score("eee", 3), <, frequency_score("zzz", 3));
+  assert_double(frequency_score(3, "eee"), <, frequency_score(3, "zzz"));
   // Space is more frequent than anything.
-  assert_double(frequency_score("   ", 3), <, frequency_score("eee", 3));
+  assert_double(frequency_score(3, "   "), <, frequency_score(3, "eee"));
 
   return MUNIT_OK;
 }