1 files changed, 51 insertions, 35 deletions

diff --git a/util/coding.h b/util/coding.h
index 1fb3d66..f0bb57b 100644
--- a/util/coding.h
+++ b/util/coding.h
@@ -10,9 +10,8 @@
 #ifndef STORAGE_LEVELDB_UTIL_CODING_H_
 #define STORAGE_LEVELDB_UTIL_CODING_H_
 
-#include <stdint.h>
-#include <string.h>
-
+#include <cstdint>
+#include <cstring>
 #include <string>
 
 #include "leveldb/slice.h"
@@ -35,7 +34,7 @@ bool GetLengthPrefixedSlice(Slice* input, Slice* result);
 
 // Pointer-based variants of GetVarint...  These either store a value
 // in *v and return a pointer just past the parsed value, or return
-// NULL on error.  These routines only look at bytes in the range
+// nullptr on error.  These routines only look at bytes in the range
 // [p..limit-1]
 const char* GetVarint32Ptr(const char* p, const char* limit, uint32_t* v);
 const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* v);
@@ -44,55 +43,72 @@ const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* v);
 int VarintLength(uint64_t v);
 
 // Lower-level versions of Put... that write directly into a character buffer
-// REQUIRES: dst has enough space for the value being written
-void EncodeFixed32(char* dst, uint32_t value);
-void EncodeFixed64(char* dst, uint64_t value);
-
-// Lower-level versions of Put... that write directly into a character buffer
 // and return a pointer just past the last byte written.
 // REQUIRES: dst has enough space for the value being written
 char* EncodeVarint32(char* dst, uint32_t value);
 char* EncodeVarint64(char* dst, uint64_t value);
 
+// Lower-level versions of Put... that write directly into a character buffer
+// REQUIRES: dst has enough space for the value being written
+
+inline void EncodeFixed32(char* dst, uint32_t value) {
+  uint8_t* const buffer = reinterpret_cast<uint8_t*>(dst);
+
+  // Recent clang and gcc optimize this to a single mov / str instruction.
+  buffer[0] = static_cast<uint8_t>(value);
+  buffer[1] = static_cast<uint8_t>(value >> 8);
+  buffer[2] = static_cast<uint8_t>(value >> 16);
+  buffer[3] = static_cast<uint8_t>(value >> 24);
+}
+
+inline void EncodeFixed64(char* dst, uint64_t value) {
+  uint8_t* const buffer = reinterpret_cast<uint8_t*>(dst);
+
+  // Recent clang and gcc optimize this to a single mov / str instruction.
+  buffer[0] = static_cast<uint8_t>(value);
+  buffer[1] = static_cast<uint8_t>(value >> 8);
+  buffer[2] = static_cast<uint8_t>(value >> 16);
+  buffer[3] = static_cast<uint8_t>(value >> 24);
+  buffer[4] = static_cast<uint8_t>(value >> 32);
+  buffer[5] = static_cast<uint8_t>(value >> 40);
+  buffer[6] = static_cast<uint8_t>(value >> 48);
+  buffer[7] = static_cast<uint8_t>(value >> 56);
+}
+
 // Lower-level versions of Get... that read directly from a character buffer
 // without any bounds checking.
 
 inline uint32_t DecodeFixed32(const char* ptr) {
-  if (port::kLittleEndian) {
-    // Load the raw bytes
-    uint32_t result;
-    memcpy(&result, ptr, sizeof(result));  // gcc optimizes this to a plain load
-    return result;
-  } else {
-    return ((static_cast<uint32_t>(static_cast<unsigned char>(ptr[0])))
-        | (static_cast<uint32_t>(static_cast<unsigned char>(ptr[1])) << 8)
-        | (static_cast<uint32_t>(static_cast<unsigned char>(ptr[2])) << 16)
-        | (static_cast<uint32_t>(static_cast<unsigned char>(ptr[3])) << 24));
-  }
+  const uint8_t* const buffer = reinterpret_cast<const uint8_t*>(ptr);
+
+  // Recent clang and gcc optimize this to a single mov / ldr instruction.
+  return (static_cast<uint32_t>(buffer[0])) |
+         (static_cast<uint32_t>(buffer[1]) << 8) |
+         (static_cast<uint32_t>(buffer[2]) << 16) |
+         (static_cast<uint32_t>(buffer[3]) << 24);
 }
 
 inline uint64_t DecodeFixed64(const char* ptr) {
-  if (port::kLittleEndian) {
-    // Load the raw bytes
-    uint64_t result;
-    memcpy(&result, ptr, sizeof(result));  // gcc optimizes this to a plain load
-    return result;
-  } else {
-    uint64_t lo = DecodeFixed32(ptr);
-    uint64_t hi = DecodeFixed32(ptr + 4);
-    return (hi << 32) | lo;
-  }
+  const uint8_t* const buffer = reinterpret_cast<const uint8_t*>(ptr);
+
+  // Recent clang and gcc optimize this to a single mov / ldr instruction.
+  return (static_cast<uint64_t>(buffer[0])) |
+         (static_cast<uint64_t>(buffer[1]) << 8) |
+         (static_cast<uint64_t>(buffer[2]) << 16) |
+         (static_cast<uint64_t>(buffer[3]) << 24) |
+         (static_cast<uint64_t>(buffer[4]) << 32) |
+         (static_cast<uint64_t>(buffer[5]) << 40) |
+         (static_cast<uint64_t>(buffer[6]) << 48) |
+         (static_cast<uint64_t>(buffer[7]) << 56);
 }
 
 // Internal routine for use by fallback path of GetVarint32Ptr
-const char* GetVarint32PtrFallback(const char* p,
-                                   const char* limit,
+const char* GetVarint32PtrFallback(const char* p, const char* limit,
                                    uint32_t* value);
-inline const char* GetVarint32Ptr(const char* p,
-                                  const char* limit,
+inline const char* GetVarint32Ptr(const char* p, const char* limit,
                                   uint32_t* value) {
   if (p < limit) {
-    uint32_t result = *(reinterpret_cast<const unsigned char*>(p));
+    uint32_t result = *(reinterpret_cast<const uint8_t*>(p));
     if ((result & 128) == 0) {
       *value = result;
       return p + 1;