From: Joel Rosdahl <joel@rosdahl.net>
Date: Mon, 21 Sep 2020 19:43:44 +0000 (+0200)
Subject: Optimize Util::format_hex
X-Git-Tag: v4.0~69
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1152b4e52b55d8d6530312f5b88cc1dc227cee0c;p=thirdparty%2Fccache.git

Optimize Util::format_hex

Not that it matters much, but not using fmt::format makes
Util::format_hex ≈20x faster.
---

diff --git a/src/Util.cpp b/src/Util.cpp
index 7b4d8b7e5..99eaf7880 100644
--- a/src/Util.cpp
+++ b/src/Util.cpp
@@ -524,10 +524,12 @@ format_argv_for_logging(const char* const* argv)
 std::string
 format_hex(const uint8_t* data, size_t size)
 {
+  static const char digits[] = "0123456789abcdef";
   std::string result;
-  result.reserve(2 * size);
-  for (size_t i = 0; i < size; i++) {
-    result += fmt::format("{:02x}", data[i]);
+  result.resize(2 * size);
+  for (size_t i = 0; i < size; ++i) {
+    result[i * 2] = digits[data[i] >> 4];
+    result[i * 2 + 1] = digits[data[i] & 0xF];
   }
   return result;
 }
diff --git a/src/third_party/base32hex.c b/src/third_party/base32hex.c
index aebfab5d5..4c2275d03 100644
--- a/src/third_party/base32hex.c
+++ b/src/third_party/base32hex.c
@@ -23,7 +23,7 @@
  * Returns length of encoded string.
  */
 unsigned int base32hex(char *out, const uint8_t *in, unsigned int len) {
-int buf = 0, bits = 0;
+unsigned int buf = 0, bits = 0;
 char *x = out;
 
     while (len-- > 0) {