Use base64 from simdutf8

CMakeLists.txt

@@ -43,6 +43,22 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(nlohmann_json)
 
+set(SIMDUTF_TESTS
+    OFF
+    CACHE BOOL "Disable simdutf tests" FORCE)
+set(SIMDUTF_BENCHMARKS
+    OFF
+    CACHE BOOL "Disable simdutf benchmarks" FORCE)
+set(SIMDUTF_TOOLS
+    OFF
+    CACHE BOOL "Disable simdutf tools" FORCE)
+FetchContent_Declare(
+  simdutf
+  GIT_REPOSITORY https://github.com/simdutf/simdutf.git
+  GIT_TAG 6aacd743d20528a2082189504ac96caf749e6c2e # v7.3.6
+)
+FetchContent_MakeAvailable(simdutf)
+
 include_directories(src)
 
 find_package(weaseljson REQUIRED)
@@ -51,7 +67,8 @@ set(SOURCES src/main.cpp src/config.cpp src/commit_request.cpp
             src/arena_allocator.cpp)
 
 add_executable(weaseldb ${SOURCES})
-target_link_libraries(weaseldb Threads::Threads toml11::toml11 weaseljson)
+target_link_libraries(weaseldb Threads::Threads toml11::toml11 weaseljson
+                      simdutf::simdutf)
 
 enable_testing()
 
@@ -67,7 +84,8 @@ target_include_directories(test_arena_allocator PRIVATE src)
 add_executable(
   test_commit_request tests/test_commit_request.cpp src/commit_request.cpp
                       src/arena_allocator.cpp)
-target_link_libraries(test_commit_request doctest::doctest weaseljson test_data)
+target_link_libraries(test_commit_request doctest::doctest weaseljson test_data
+                      simdutf::simdutf)
 target_include_directories(test_commit_request PRIVATE src)
 
 add_executable(bench_arena_allocator benchmarks/bench_arena_allocator.cpp
@@ -78,20 +96,21 @@ target_include_directories(bench_arena_allocator PRIVATE src)
 add_executable(
   bench_commit_request benchmarks/bench_commit_request.cpp
                        src/commit_request.cpp src/arena_allocator.cpp)
-target_link_libraries(bench_commit_request nanobench weaseljson test_data)
+target_link_libraries(bench_commit_request nanobench weaseljson test_data
+                      simdutf::simdutf)
 target_include_directories(bench_commit_request PRIVATE src)
 
 add_executable(
   bench_parser_comparison benchmarks/bench_parser_comparison.cpp
                           src/commit_request.cpp src/arena_allocator.cpp)
 target_link_libraries(bench_parser_comparison nanobench weaseljson test_data
-                      nlohmann_json::nlohmann_json)
+                      nlohmann_json::nlohmann_json simdutf::simdutf)
 target_include_directories(bench_parser_comparison PRIVATE src)
 
 # Debug tools
 add_executable(debug_arena tools/debug_arena.cpp src/commit_request.cpp
                            src/arena_allocator.cpp)
-target_link_libraries(debug_arena weaseljson)
+target_link_libraries(debug_arena weaseljson simdutf::simdutf)
 target_include_directories(debug_arena PRIVATE src)
 
 add_test(NAME arena_allocator_tests COMMAND test_arena_allocator)

src/arena_allocator.hpp

@@ -227,7 +227,8 @@ public:
    * @param ptr Pointer to the existing allocation (must be from this allocator)
    * @param old_size Size of the existing allocation in bytes
    * @param new_size Desired new size in bytes
-   * @param alignment Required alignment
+   * @param alignment Required alignment. Defaults to
+   * `alignof(std::max_align_t)`
    * @return Pointer to the reallocated memory (may be the same as ptr or
    * different)
    * @throws std::bad_alloc if memory allocation fails
@@ -253,7 +254,7 @@ public:
    * - When copying to new location, uses the specified alignment
    */
   void *realloc_raw(void *ptr, uint32_t old_size, uint32_t new_size,
-                    uint32_t alignment);
+                    uint32_t alignment = alignof(std::max_align_t));
 
   /**
    * @brief Type-safe version of realloc_raw for arrays of type T.

src/commit_request.cpp

@@ -1,7 +1,7 @@
 #include "commit_request.hpp"
-#include <array>
 #include <charconv>
 #include <cstring>
+#include <simdutf.h>
 
 // Global callbacks for JSON parsing
 const WeaselJsonCallbacks CommitRequest::json_callbacks = {
@@ -17,29 +17,6 @@ const WeaselJsonCallbacks CommitRequest::json_callbacks = {
     .on_null_literal = CommitRequest::on_null_literal,
 };
 
-namespace {
-// Base64 decoding table
-constexpr std::array<int, 256> make_base64_decode_table() {
-  std::array<int, 256> table{};
-  for (int i = 0; i < 256; ++i) {
-    table[i] = -1;
-  }
-  for (int i = 0; i < 26; ++i) {
-    table['A' + i] = i;
-    table['a' + i] = i + 26;
-  }
-  for (int i = 0; i < 10; ++i) {
-    table['0' + i] = i + 52;
-  }
-  table['+'] = 62;
-  table['/'] = 63;
-  table['='] = -2; // Padding
-  return table;
-}
-
-constexpr auto base64_decode_table = make_base64_decode_table();
-} // namespace
-
 std::string_view CommitRequest::store_string(std::string_view str) {
   if (str.empty()) {
     return {};
@@ -65,47 +42,29 @@ std::string_view CommitRequest::decode_base64(std::string_view base64_str) {
     return {};
   }
 
-  // Remove padding for size calculation
-  size_t input_len = base64_str.size();
-  while (input_len > 0 && base64_str[input_len - 1] == '=') {
-    input_len--;
-  }
+  // Calculate maximum possible output size
+  size_t max_output_len = simdutf::maximal_binary_length_from_base64(
+      base64_str.data(), base64_str.size());
 
-  // Calculate output size
-  size_t output_len = (input_len * 3) / 4;
-
-  if (output_len == 0) {
+  if (max_output_len == 0) {
     return {};
   }
 
-  char *output = arena_.allocate<char>(output_len);
+  char *output = arena_.allocate<char>(max_output_len);
   if (!output) {
     return {};
   }
 
-  size_t out_pos = 0;
-  int bits_collected = 0;
-  int accumulator = 0;
+  // Use simdutf to decode base64
+  simdutf::result result = simdutf::base64_to_binary(
+      base64_str.data(), base64_str.size(), output, simdutf::base64_default);
 
-  for (char c : base64_str.substr(0, input_len)) {
-    int value = base64_decode_table[static_cast<unsigned char>(c)];
-    if (value < 0) {
-      return {}; // Invalid character
-    }
-
-    accumulator = (accumulator << 6) | value;
-    bits_collected += 6;
-
-    if (bits_collected >= 8) {
-      bits_collected -= 8;
-      if (out_pos < output_len) {
-        output[out_pos++] =
-            static_cast<char>((accumulator >> bits_collected) & 0xFF);
-      }
-    }
+  if (result.error != simdutf::error_code::SUCCESS) {
+    parser_context_.parse_error = "Decoding base64 failed";
+    return {};
   }
 
-  return std::string_view(output, out_pos);
+  return std::string_view(output, result.count);
 }
 
 void CommitRequest::on_begin_object(void *userdata) {