Avoid use of strtoul()

This function is overkill for the simple cases actually needed here, and pretty
slow anyway.

3 files changed, 16 insertions, 9 deletions

diff --git a/src/n3.c b/src/n3.c
index d332504d..d5866393 100644
--- a/src/n3.c
+++ b/src/n3.c
@@ -15,7 +15,6 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
 #if defined(__clang__) && __clang_major__ >= 10
@@ -71,17 +70,18 @@ read_UCHAR(SerdReader* const reader, const Ref dest, uint32_t* const char_code)
 
   skip_byte(reader, b);
 
-  uint8_t buf[9] = {0, 0, 0, 0, 0, 0, 0, 0, 0};
-  for (unsigned i = 0; i < length; ++i) {
+  // Read character code point in hex
+  uint8_t  buf[9] = {0, 0, 0, 0, 0, 0, 0, 0, 0};
+  uint32_t code   = 0U;
+  for (unsigned i = 0U; i < length; ++i) {
     if (!(buf[i] = read_HEX(reader))) {
       return SERD_ERR_BAD_SYNTAX;
     }
-  }
 
-  char*          endptr = NULL;
-  const uint32_t code   = (uint32_t)strtoul((const char*)buf, &endptr, 16);
-  assert(endptr == (char*)buf + length);
+    code = (code << (i ? 4U : 0U)) | hex_digit_value(buf[i]);
+  }
 
+  // Determine the encoded size from the code point
   unsigned size = 0;
   if (code < 0x00000080) {
     size = 1;
diff --git a/src/string_utils.h b/src/string_utils.h
index 9ae0abcb..7770e1eb 100644
--- a/src/string_utils.h
+++ b/src/string_utils.h
@@ -89,6 +89,12 @@ serd_substrlen(const uint8_t* str,
                size_t*        n_bytes,
                SerdNodeFlags* flags);
 
+static inline uint8_t
+hex_digit_value(const uint8_t c)
+{
+  return (uint8_t)((c > '9') ? ((c & ~0x20) - 'A' + 10) : (c - '0'));
+}
+
 static inline char
 serd_to_upper(const char c)
 {
diff --git a/src/uri.c b/src/uri.c
index d78b8e8c..b45f7e16 100644
--- a/src/uri.c
+++ b/src/uri.c
@@ -72,8 +72,9 @@ serd_file_uri_parse(const uint8_t* const uri, uint8_t** const hostname)
         serd_chunk_sink("%", 1, &chunk);
         ++s;
       } else if (is_hexdig(*(s + 1)) && is_hexdig(*(s + 2))) {
-        const uint8_t code[3] = {*(s + 1), *(s + 2), 0};
-        const uint8_t c       = (uint8_t)strtoul((const char*)code, NULL, 16);
+        const uint8_t hi = hex_digit_value(s[1]);
+        const uint8_t lo = hex_digit_value(s[2]);
+        const char    c  = (char)((hi << 4U) | lo);
         serd_chunk_sink(&c, 1, &chunk);
         s += 2;
       } else {