Move useful functions to separate file

ex01/main.c

@@ -1,39 +1,6 @@
-#include <ctype.h>
+#include "utils.h"
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
-
-size_t hex_to_binary(unsigned char *out, const char hex[static 1]) {
-  for (size_t i = 0; i < strlen(hex); ++i) {
-    char c = tolower(hex[i]);
-    unsigned char value;
-    if (isdigit(c)) {
-      value = c - '0';
-    } else {
-      value = 10 + c - 'a';
-    }
-    if (i % 2 == 0) {
-      value <<= 4;
-    }
-    out[i / 2] += value;
-  }
-  return strlen(hex) / 2 + strlen(hex) % 2;
-}
-
-unsigned char *binary_to_base64(unsigned char *out,
-                                const unsigned char in[static 1], size_t len) {
-  static const unsigned char base64_table[65] =
-      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-
-  for (size_t i = 0; i < len - 2; i += 3) {
-    size_t j = i / 3 * 4;
-    out[j] = base64_table[in[i] >> 2];
-    out[j+1] = base64_table[((in[i] & 0x03) << 4) | (in[i+1] >> 4)];
-    out[j+2] = base64_table[((in[i+1] & 0x0f) << 2) | (in[i+2] >> 6)];
-    out[j+3] = base64_table[in[i+2] & 0x3f];
-  }
-  return out;
-}
 
 int main(int argc, char *argv[argc + 1]) {
   if (argc < 2) {
@@ -42,9 +9,9 @@ int main(int argc, char *argv[argc + 1]) {
   }
 
   unsigned char buf[512] = {0};
-  size_t len = hex_to_binary(buf, argv[1]);
+  size_t len = hex_to_bytes(buf, argv[1]);
   unsigned char out[512] = {'\0'};
-  binary_to_base64(out, buf, len);
+  bytes_to_base64(out, buf, len);
   printf("%s\n", out);
 
   return EXIT_SUCCESS;