Add hex encoding/decoding

src/string.c

@@ -93,6 +93,58 @@ S64 str_index(Str haystack, Str needle)
     return -1;
 }
 
+static const char hex_chars[] = "0123456789ABCDEF";
+
+Str str_hex_encode(Str source, Str destination)
+{
+    Assert(destination.len  >= source.len * 2);
+    U32 hex_len = source.len * 2;
+    for (U32 i = 0, t = 0; i < source.len; ++i,t+=2) {
+        U8 high_nibble;
+        U8 low_nibble;
+
+        high_nibble = (source.str[i] & 0xF0) >> 4 ;
+        low_nibble =  source.str[i] & 0x0F ;
+
+        destination.str[t]   = hex_chars[high_nibble];
+        destination.str[t+1] = hex_chars[low_nibble];
+    }
+
+    destination.len = hex_len;
+    return destination;
+}
+
+Str str_hex_decode(Str source, Str destination)
+{
+    Assert(destination.len >= source.len/2);
+    U32 dest_pos = 0;
+    U32 source_pos = 0;
+
+    while (source_pos + 1 < source.len) {
+
+        if (char_is_ascii_whitespace(source.str[source_pos])) {
+            source_pos++;
+            continue;
+        }
+
+        S16 high_nibble;
+        S16 low_nibble;
+
+        high_nibble = char_hex_to_binary(source.str[source_pos]);
+        low_nibble = char_hex_to_binary(source.str[source_pos + 1]);
+        if (high_nibble == -1 || low_nibble == -1) {
+            destination.len = 0;
+            return destination;
+        }
+
+        destination.str[dest_pos] = (high_nibble << 4 ) | low_nibble;
+        source_pos += 2;
+        dest_pos++;
+    }
+
+    destination.len = dest_pos;
+    return destination;
+}
 // split @str on any byte in @separators, place split strings in @vec
 void str_split(Str str, Str separators, StrVec *vec)
 {