From 1770c8b9f3b95e649d8d33fa14acf64653c51949 Mon Sep 17 00:00:00 2001
From: Stephane Janel <stephane.janel@amadeus.com>
Date: Sat, 20 Apr 2024 20:40:55 +0200
Subject: [PATCH] [Code refactoring] - Base64 code clean up

---
 src/tech/include/base64.hpp | 39 ++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/src/tech/include/base64.hpp b/src/tech/include/base64.hpp
index 688b1856..0ebbde20 100644
--- a/src/tech/include/base64.hpp
+++ b/src/tech/include/base64.hpp
@@ -2,6 +2,9 @@
 
 #include <algorithm>
 #include <array>
+#include <climits>
+#include <cstddef>
+#include <cstdint>
 #include <span>
 
 #include "cct_string.hpp"
@@ -9,25 +12,25 @@
 namespace cct {
 
 namespace details {
-inline void B64Encode(std::span<const char> binData, char *out, char *endOut) {
-  int bitsCollected = 0;
-  unsigned int accumulator = 0;
+inline void B64EncodeImpl(std::span<const char> binData, char *out, char *endOut) {
+  int bitsCollected{};
+  uint32_t accumulator{};
 
-  static constexpr const char *const kB64Table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+  static constexpr const char kB64Table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+  static constexpr auto kB64NbBits = 6;
+  static constexpr decltype(accumulator) kMask6 = (1U << kB64NbBits) - 1U;
 
-  for (char ch : binData) {
-    accumulator = (accumulator << 8) | (ch & 0xFFU);
-    bitsCollected += 8;
-    while (bitsCollected >= 6) {
-      bitsCollected -= 6;
-      *out = kB64Table[(accumulator >> bitsCollected) & 0x3FU];
-      ++out;
+  for (uint8_t ch : binData) {
+    accumulator = (accumulator << CHAR_BIT) | ch;
+    bitsCollected += CHAR_BIT;
+    while (bitsCollected >= kB64NbBits) {
+      bitsCollected -= kB64NbBits;
+      *out++ = kB64Table[(accumulator >> bitsCollected) & kMask6];
     }
   }
   if (bitsCollected > 0) {
-    accumulator <<= 6 - bitsCollected;
-    *out = kB64Table[accumulator & 0x3FU];
-    ++out;
+    accumulator <<= kB64NbBits - bitsCollected;
+    *out++ = kB64Table[accumulator & kMask6];
   }
 
   std::fill(out, endOut, '=');
@@ -39,7 +42,7 @@ constexpr auto B64EncodedLen(auto binDataLen) { return static_cast<std::size_t>(
 
 [[nodiscard]] inline string B64Encode(std::span<const char> binData) {
   string ret(details::B64EncodedLen(binData.size()), 0);
-  details::B64Encode(binData, ret.data(), ret.data() + ret.size());
+  details::B64EncodeImpl(binData, ret.data(), ret.data() + ret.size());
   return ret;
 }
 string B64Encode(const char *) = delete;
@@ -47,18 +50,18 @@ string B64Encode(const char *) = delete;
 template <std::size_t N>
 [[nodiscard]] auto B64Encode(const char (&binData)[N]) {
   std::array<char, details::B64EncodedLen(N)> ret;
-  details::B64Encode(binData, ret.data(), ret.data() + ret.size());
+  details::B64EncodeImpl(binData, ret.data(), ret.data() + ret.size());
   return ret;
 }
 
 template <std::size_t N>
 [[nodiscard]] auto B64Encode(const std::array<char, N> &binData) {
   std::array<char, details::B64EncodedLen(N)> ret;
-  details::B64Encode(binData, ret.data(), ret.data() + ret.size());
+  details::B64EncodeImpl(binData, ret.data(), ret.data() + ret.size());
   return ret;
 }
 
 [[nodiscard]] string B64Decode(std::span<const char> ascData);
 string B64Decode(const char *) = delete;
 
-}  // namespace cct
\ No newline at end of file
+}  // namespace cct