update: several improvements of ShortCode

src/core/benchmark/codec.cc

@@ -166,7 +166,7 @@ static void ShortCodeSerialize(benchmark::State &state) {
     for (auto _ : state) {
 
         for (const auto code : samples) {
-            volatile auto ret = klotski::codec::ShortCode::string_encode(code);
+            volatile auto ret = ShortCode::string_encode(code);
         }
 
     }
@@ -185,7 +185,7 @@ static void ShortCodeDeserialize(benchmark::State &state) {
 
         for (const auto code : samples) {
 
-            volatile auto ret = klotski::codec::ShortCode::string_decode(code);
+            volatile auto ret = ShortCode::string_decode(code);
 
         }
 
@@ -197,8 +197,8 @@ static void ShortCodeDeserialize(benchmark::State &state) {
 
 static void ShortCodeToCommonCode(benchmark::State &state) {
 
-    ShortCode::speed_up(true);
-    // ShortCode::speed_up(false);
+    // ShortCode::speed_up(true);
+    ShortCode::speed_up(false);
 
     // ShortCode::fast_decode(4091296);
 
@@ -221,8 +221,8 @@ static void ShortCodeToCommonCode(benchmark::State &state) {
 }
 
 static void CommonCodeToShortCode(benchmark::State &state) {
-    ShortCode::speed_up(true);
-    // ShortCode::speed_up(false);
+    // ShortCode::speed_up(true);
+    ShortCode::speed_up(false);
 
     auto common_code = CommonCode::unsafe_create(0x1A9BF0C00);
 
@@ -248,11 +248,11 @@ static void CommonCodeToShortCode(benchmark::State &state) {
 // BENCHMARK(CommonCodeSerializeShorten)->Range(8, 256);
 // BENCHMARK(CommonCodeDeserializeShorten)->Range(8, 256);
 
-// BENCHMARK(ShortCodeSerialize)->Range(8, 256);
-// BENCHMARK(ShortCodeDeserialize)->Range(8, 256);
+BENCHMARK(ShortCodeSerialize)->Range(8, 256);
+BENCHMARK(ShortCodeDeserialize)->Range(8, 256);
 
 // BENCHMARK(ShortCodeToCommonCode);
-BENCHMARK(CommonCodeToShortCode);
+// BENCHMARK(CommonCodeToShortCode);
 
 // static void CommonCodeDecode(benchmark::State &state) {
 //     const auto tmp = str_common_codes(state.range(0));

src/core/short_code/internal/offset/offset.h

@@ -6,9 +6,9 @@
 
 namespace klotski::codec {
 
-/// This is the index for basic ranges, and its position (0 ~ 7311884) in all
-/// basic ranges is located according to the first 12-bit (0 ~ 4095) within the
-/// 32-bit `range`.
+/// This is the offset index of basic ranges, and its position (0 ~ 7311884) in
+/// all basic ranges is located according to the first 12-bit (0 ~ 4095) within
+/// the 32-bit `range` value.
 
 constexpr auto RANGES_GLOBAL_OFFSET = std::to_array<uint32_t>({
     #include "constant/offset.inc"

src/core/short_code/internal/serialize.cc

@@ -1,34 +1,38 @@
+#include <ranges>
+
 #include "serialize_chars.h"
 #include "short_code/short_code.h"
 
 using klotski::codec::ShortCode;
+using klotski::cases::ALL_CASES_NUM_;
 
 std::string ShortCode::string_encode(uint32_t short_code) {
-    char result[5];
-    for (int n = 0; n < 5; ++n) {
-        result[4 - n] = SHORT_CODE_TABLE[short_code & 0b11111];
+    KLSK_ASSUME(short_code < ALL_CASES_NUM_);
+    std::array<char, 5> arr {};
+    for (auto &c : arr | std::views::reverse) {
+        c = SHORT_CODE_TABLE[short_code & 0b11111]; // table convert
         short_code >>= 5;
     }
-    return {result, result + 5};
+    return {arr.begin(), arr.end()};
 }
 
 std::optional<uint32_t> ShortCode::string_decode(const std::string_view short_code) {
     if (short_code.length() != 5) {
         return std::nullopt; // invalid string length
     }
-    uint32_t result = 0;
-    for (auto bit : short_code) {
-        if (bit < '1' || bit > 'z') { // invalid characters
+    uint32_t code = 0;
+    for (const uint8_t bit : short_code) {
+        if (bit > 'z') { // invalid characters
             return std::nullopt;
         }
-        result <<= 5;
-        result += (bit = SHORT_CODE_TABLE_REV[bit - 49]); // table convert
-        if (bit == -1) { // invalid character
-            return std::nullopt;
+        if (const auto val = SHORT_CODE_TABLE_REV[bit]; val != -1) {
+            (code <<= 5) += val;
+            continue;
         }
+        return std::nullopt; // invalid character
     }
-    if (!check(result)) { // check converted short code
+    if (!check(code)) { // check converted short code
         return std::nullopt;
     }
-    return result; // apply convert result
+    return code; // apply convert result
 }

src/core/short_code/internal/serialize_chars.h

@@ -1,5 +1,3 @@
-#pragma once
-
 ///                ShortCode Convert Table                ///
 ///   -------------------------------------------------   ///
 ///   |  00 |  01 |  02 |  03 |  04 |  05 |  06 |  07 |   ///
@@ -15,17 +13,28 @@
 ///   | `S` | `T` | `U` | `V` | `W` | `X` | `Y` | `Z` |   ///
 ///   -------------------------------------------------   ///
 
+#pragma once
+
+#include <array>
+
 namespace klotski::codec {
 
-constexpr char SHORT_CODE_TABLE[32] {
+constexpr auto SHORT_CODE_TABLE = std::to_array<char>({
     '1', '2', '3', '4', '5', '6', '7', '8', '9', // skip `0`
     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // skip `I`
     'J', 'K', // skip `L`
     'M', 'N', // skip `O`
     'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
-};
+});
+
+static_assert(SHORT_CODE_TABLE.size() == 32);
 
-constexpr char SHORT_CODE_TABLE_REV[74] {
+constexpr auto SHORT_CODE_TABLE_REV = std::to_array<char>({
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, //           | [0, 9]
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, //           | [10, 19]
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, //           | [20, 29]
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, //           | [30, 39]
+    -1, -1, -1, -1, -1, -1, -1, -1, -1,     //           | [40, 48]
      0,  1,  2,  3,  4,  5,  6,  7,  8,     // `1` ~ `9` | [49, 57]
     -1, -1, -1, -1, -1, -1, -1,             //           | [58, 64]
      9, 10, 11, 12, 13, 14, 15, 16, -1, 17, // `A` ~ `J` | [65, 74]
@@ -35,6 +44,8 @@ constexpr char SHORT_CODE_TABLE_REV[74] {
      9, 10, 11, 12, 13, 14, 15, 16, -1, 17, // `a` ~ `j` | [97, 106]
     18, -1, 19, 20, -1, 21, 22, 23, 24, 25, // `k` ~ `t` | [107, 116]
     26, 27, 28, 29, 30, 31,                 // `u` ~ `z` | [117, 122]
-};
+});
+
+static_assert(SHORT_CODE_TABLE_REV.size() == 'z' + 1);
 
 } // namespace klotski::codec

src/core/short_code/internal/short_code.inl

@@ -1,12 +1,10 @@
 #pragma once
 
-#include <bit>
-
 #include "common_code/common_code.h"
 
 namespace klotski::codec {
 
-// ------------------------------------------------------------------------------------- //
+// ----------------------------------------------------------------------------------------- //
 
 inline ShortCode::ShortCode(const CommonCode common_code) {
     if (fast_) {
@@ -27,7 +25,7 @@ inline std::optional<ShortCode> ShortCode::create(const uint32_t short_code) {
     return unsafe_create(short_code);
 }
 
-// ------------------------------------------------------------------------------------- //
+// ----------------------------------------------------------------------------------------- //
 
 inline ShortCode::operator uint32_t() const {
     return code_;
@@ -97,7 +95,7 @@ inline std::optional<ShortCode> ShortCode::from_common_code(const std::string_vi
     return CommonCode::from_string(common_code).transform(convert);
 }
 
-// ------------------------------------------------------------------------------------- //
+// ----------------------------------------------------------------------------------------- //
 
 constexpr auto operator==(const ShortCode &lhs, const uint32_t rhs) {
     return lhs.code_ == rhs;

src/core/short_code/short_code.h

@@ -1,7 +1,7 @@
 /// Klotski Engine by Dnomd343 @2024
 
 /// ShortCode is a high-compression encoding scheme based on CommonCode. Since
-/// there are a total of 29334498 valid klotski cases, arrange then from small
+/// there are a total of 29334498 valid klotski cases, arrange them from small
 /// to large by their CommonCodes (36-bit positive integers), and use the index
 /// as the ShortCode.
 
@@ -160,7 +160,7 @@ private:
     static KLSK_INLINE uint64_t fast_decode(uint32_t short_code);
 
     /// Convert CommonCode to ShortCode based on AllCases data.
-    static uint32_t fast_encode(uint64_t common_code);
+    static KLSK_INLINE uint32_t fast_encode(uint64_t common_code);
 
     /// Convert ShortCode to CommonCode based on BasicRanges data.
     static uint64_t tiny_decode(uint32_t short_code);
@@ -171,10 +171,10 @@ private:
     // ------------------------------------------------------------------------------------- //
 
     /// Serialize ShortCode into 5-bit length string.
-    static std::string string_encode(uint32_t short_code);
+    static KLSK_INLINE std::string string_encode(uint32_t short_code);
 
     /// Deserialize ShortCode from string and return nullopt on error.
-    static std::optional<uint32_t> string_decode(std::string_view short_code);
+    static KLSK_INLINE std::optional<uint32_t> string_decode(std::string_view short_code);
 
     // ------------------------------------------------------------------------------------- //
 
@@ -193,6 +193,9 @@ private:
     // ------------------------------------------------------------------------------------- //
 };
 
+static_assert(std::is_standard_layout_v<ShortCode>);
+static_assert(std::is_trivially_copyable_v<ShortCode>);
+
 } // namespace klotski::codec
 
 #include "internal/short_code.inl"