update: fixes and improvements

benchmark.cc

@@ -20,6 +20,15 @@ static void MD5_Update(benchmark::State &state) {
     }
 }
 
+static void MD5_Digest(benchmark::State &state) {
+    md5::MD5 kk;
+    for (auto _ : state) {
+        auto pp = kk.Digest();
+    }
+}
+
 BENCHMARK(MD5_Update);
 
+BENCHMARK(MD5_Digest);
+
 BENCHMARK_MAIN();

src/core.cc

@@ -58,13 +58,13 @@ consteval uint32_t T(int index) { // index -> [0, 64)
     return static_cast<uint32_t>(std::abs(val) * 0x100000000);
 }
 
-void MD5::md5_update(md5_ctx *ctx, const void *data, uint64_t len) {
-    auto *block = reinterpret_cast<const uint32_t *>(data);
-    auto *limit = block + (len >> 2);
-    auto A = ctx->A;
-    auto B = ctx->B;
-    auto C = ctx->C;
-    auto D = ctx->D;
+const void* MD5::UpdateImpl(const void *data, uint64_t len) {
+    auto *block = static_cast<const uint32_t *>(data);
+    auto *limit = block + ((len &= ~0b111111ULL) >> 2);
+    auto A = ctx_.A;
+    auto B = ctx_.B;
+    auto C = ctx_.C;
+    auto D = ctx_.D;
 
     while (block < limit) {
         auto A_ = A;
@@ -82,33 +82,32 @@ void MD5::md5_update(md5_ctx *ctx, const void *data, uint64_t len) {
         block += 16; // move to next block
     }
 
-    ctx->A = A;
-    ctx->B = B;
-    ctx->C = C;
-    ctx->D = D;
-    ctx->size += len;
+    ctx_.A = A;
+    ctx_.B = B;
+    ctx_.C = C;
+    ctx_.D = D;
+    ctx_.size += len;
+    return static_cast<const void *>(limit);
 }
 
-void MD5::md5_final(md5_ctx *ctx, const void *data, uint64_t len) {
+void MD5::FinalImpl(const void *data, uint64_t len) {
     if (len >= 120) { // len -> [64 + 56, INF)
-        auto size = len & ~(uint64_t)0b111111;
-        md5_update(ctx, data, size);
-        data = reinterpret_cast<const char*>(data) + size;
+        data = UpdateImpl(data, len);
         len &= 0b111111; // len -> [0, 64)
     }
 
     unsigned char buffer[128]; // 2 blocks
     std::memcpy(buffer, data, len);
-    uint64_t total = (ctx->size + len) << 3; // total number in bit
+    uint64_t total = (ctx_.size + len) << 3; // total number in bit
 
     if (len < 56) { // len -> [0, 56)
         std::memcpy(buffer + len, Padding, 56 - len);
         std::memcpy(buffer + 56, &total, 8);
-        md5_update(ctx, buffer, 64); // update 1 block
+        UpdateImpl(buffer, 64); // update 1 block
     } else { // len -> [56, 64 + 56)
         std::memcpy(buffer + len, Padding, 120 - len);
         std::memcpy(buffer + 120, &total, 8);
-        md5_update(ctx, buffer, 128); // update 2 blocks
+        UpdateImpl(buffer, 128); // update 2 blocks
     }
 }
 

src/md5.h

@@ -15,16 +15,26 @@ class MD5 {
 public:
     MD5() = default;
 
-    MD5& Final();
+    /// Reset for next round of hashing.
     MD5& Reset();
 
+    /// Update md5 hash with specified data.
     MD5& Update(const std::string_view &data);
-    MD5& Update(const void *buffer, uint64_t len);
 
+    /// Update md5 hash with specified data.
+    MD5& Update(const void *data, uint64_t len);
+
+    /// Stop streaming updates and calculate result.
+    MD5& Final();
+
+    /// Get the string result of md5.
     [[nodiscard]] std::string Digest() const;
 
 public:
+    /// Calculate the md5 hash value of the specified data.
     static std::string Hash(const std::string_view &data);
+
+    /// Calculate the md5 hash value of the specified data.
     static std::string Hash(const void *data, uint64_t len);
 
 private:
@@ -44,14 +54,15 @@ private:
 private:
     md5_ctx ctx_;
     char buffer_[64] {};
-    uint64_t buffer_size_ = 0;
+    uint64_t buffer_size_ = 0; // size < 64
 
-private:
-    /// Update md5 ctx with specified data, note that `len` is a multiple of 64.
-    static void md5_update(md5_ctx *ctx, const void *buffer, uint64_t len);
+    /// Update md5 ctx with specified data, and return the pointer of unprocessed data (< 64 bytes).
+    const void* UpdateImpl(const void *data, uint64_t len);
 
-    /// Update and end the md5 hash with the specified data, the value of `len` has no limit.
-    static void md5_final(md5_ctx *ctx, const void *buffer, uint64_t len);
+    /// Update and final the md5 hash with the specified data.
+    void FinalImpl(const void *data, uint64_t len);
 };
 
 } // namespace md5
+
+#include "md5.inc"

src/md5.inc

@@ -0,0 +1,34 @@
+#pragma once
+
+namespace md5 {
+
+inline MD5& MD5::Reset() {
+    ctx_.A = MD5_A;
+    ctx_.B = MD5_B;
+    ctx_.C = MD5_C;
+    ctx_.D = MD5_D;
+    ctx_.size = 0;
+    buffer_size_ = 0;
+    return *this;
+}
+
+inline MD5& MD5::Final() {
+    FinalImpl(buffer_, buffer_size_);
+    return *this;
+}
+
+inline MD5& MD5::Update(const std::string_view &data) {
+    return Update(data.data(), data.size());
+}
+
+inline std::string MD5::Hash(const std::string_view &data) {
+    return Hash(data.data(), data.size());
+}
+
+inline std::string MD5::Hash(const void *data, uint64_t len) {
+    MD5 md5;
+    md5.FinalImpl(data, len);
+    return md5.Digest();
+}
+
+} // namespace md5

src/wrapper.cc

@@ -4,18 +4,6 @@
 
 namespace md5 {
 
-// TODO: inline impl
-MD5& MD5::Reset() {
-    ctx_.A = MD5_A;
-    ctx_.B = MD5_B;
-    ctx_.C = MD5_C;
-    ctx_.D = MD5_D;
-
-    ctx_.size = 0;
-    buffer_size_ = 0;
-    return *this;
-}
-
 MD5& MD5::Update(const void *data, uint64_t len) {
     if (buffer_size_ != 0) {
         if (buffer_size_ + len < 64) { // buffer not filled
@@ -26,15 +14,13 @@ MD5& MD5::Update(const void *data, uint64_t len) {
 
         auto size = 64 - buffer_size_;
         std::memcpy(buffer_ + buffer_size_, data, size);
-        md5_update(&ctx_, buffer_, 64); // fill and update with buffer
-        data = reinterpret_cast<const char*>(data) + size;
+        UpdateImpl(buffer_, 64); // fill and update with buffer
+        data = static_cast<const char*>(data) + size;
         buffer_size_ = 0;
         len -= size;
     } // buffer is empty for now
 
-    auto size = len & ~(uint64_t)0b111111;
-    md5_update(&ctx_, data, size);
-    data = reinterpret_cast<const char*>(data) + size;
+    data = UpdateImpl(data, len);
     len &= 0b111111; // len -> [0, 64)
 
     if (len != 0) {
@@ -44,42 +30,20 @@ MD5& MD5::Update(const void *data, uint64_t len) {
     return *this;
 }
 
-MD5& MD5::Update(const std::string_view &data) {
-    return Update(data.data(), data.size());
-}
-
-MD5& MD5::Final() {
-    md5_final(&ctx_, buffer_, buffer_size_);
-    return *this;
-}
+static constexpr char HexTable[] = {
+    '0','1','2','3','4','5','6','7',
+    '8','9','a','b','c','d','e','f',
+};
 
 std::string MD5::Digest() const {
-    // TODO: perf convert speed
-    char tmp[33];
-    sprintf(tmp, "%08x%08x%08x%08x",
-            __builtin_bswap32(ctx_.A),
-            __builtin_bswap32(ctx_.B),
-            __builtin_bswap32(ctx_.C),
-            __builtin_bswap32(ctx_.D));
-    return {tmp};
-}
-
-std::string MD5::Hash(const void *data, uint64_t len) {
-    md5_ctx ctx;
-    md5_final(&ctx, data, len);
-
-    // TODO: perf convert speed
-    char tmp[33];
-    sprintf(tmp, "%08x%08x%08x%08x",
-            __builtin_bswap32(ctx.A),
-            __builtin_bswap32(ctx.B),
-            __builtin_bswap32(ctx.C),
-            __builtin_bswap32(ctx.D));
-    return {tmp};
-}
-
-std::string MD5::Hash(const std::string_view &data) {
-    return Hash(data.data(), data.size());
+    std::string result {};
+    result.resize(32);
+    auto *src = reinterpret_cast<const uint8_t *>(&ctx_);
+    for (int i = 0; i < 32; ++src) {
+        result[i++] = HexTable[*src >> 4];
+        result[i++] = HexTable[*src & 0b1111];
+    }
+    return result;
 }
 
 } // namespace md5