From ac0fa89f10c8338b87f68265900e0043d1fe6288 Mon Sep 17 00:00:00 2001
From: Dnomd343 <i@343.re>
Date: Fri, 6 Jan 2023 11:12:49 +0800
Subject: [PATCH] feat: tiny decode function for short code

---
 klotski/main.cc       |  9 +++++++--
 klotski/short_code.cc | 35 +++++++++++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/klotski/main.cc b/klotski/main.cc
index d4d77e2..e243018 100644
--- a/klotski/main.cc
+++ b/klotski/main.cc
@@ -18,7 +18,7 @@ int main() {
 //    }
 
 //    auto s = ShortCode();
-    auto s = ShortCode(ShortCode::Mode::NORMAL);
+//    auto s = ShortCode(ShortCode::Mode::NORMAL);
 //    auto s = ShortCode(ShortCode::Mode::FAST);
 
 //    s.speed_up(ShortCode::Mode::FAST);
@@ -29,7 +29,12 @@ int main() {
 //    printf("%09lX\n", s.fast_decode(14323231));
 
 //    s.speed_up(ShortCode::Mode::NORMAL);
-    std::cout << s.basic_ranges.size() << std::endl;
+//    std::cout << s.basic_ranges.size() << std::endl;
+
+    auto s = ShortCode();
+    s.speed_up(ShortCode::Mode::NORMAL); // enter normal mode first
+
+    printf("%09lX\n", s.tiny_decode(14323231));
 
     return 0;
 }
diff --git a/klotski/short_code.cc b/klotski/short_code.cc
index 3997bee..edb61c3 100644
--- a/klotski/short_code.cc
+++ b/klotski/short_code.cc
@@ -1,3 +1,4 @@
+#include "common.h"
 #include "all_cases.h"
 #include "short_code.h"
 #include "short_code_mark.h"
@@ -39,12 +40,42 @@ void ShortCode::build_mappings() { // build fast search mappings
     }
 }
 
-uint64_t ShortCode::fast_decode(uint32_t short_code) { // short_code -> common_code
+uint64_t ShortCode::fast_decode(uint32_t short_code) { // short_code --fast--> common_code
     // TODO: ensure input short_code < SHORT_CODE_LIMIT
     return all_cases_list[short_code];
 }
 
-uint32_t ShortCode::fast_encode(uint64_t common_code) { // common_code -> short_code
+uint32_t ShortCode::fast_encode(uint64_t common_code) { // common_code --fast--> short_code
     // TODO: ensure input common_code valid
     return all_cases_dict[common_code];
 }
+
+// TODO: load basic ranges before tiny_decode
+// TODO: ensure input short_code < SHORT_CODE_LIMIT
+uint64_t ShortCode::tiny_decode(uint32_t short_code) { // short_code --low-mem--> common_code
+    uint32_t head = 0, prefix = 0;
+    for (; head < 16; ++head) {
+        if (short_code < ALL_CASES_INDEX[head]) { // match head
+            break;
+        }
+        short_code -= ALL_CASES_INDEX[head]; // short code approximate
+    }
+    for (; prefix < 256; ++prefix) {
+        if (short_code < RANGE_PREFIX_INDEX[head][prefix]) { // match range prefix
+            break;
+        }
+        short_code -= RANGE_PREFIX_INDEX[head][prefix]; // short code approximate
+    }
+
+    uint32_t range;
+    for (int index = 0; index < BASIC_RANGES_INDEX[prefix]; ++index) { // traverse basic ranges
+        range = basic_ranges[index + BASIC_RANGES_OFFSET[prefix]];
+        if (Common::check_case(head, range)) { // search for valid cases
+            if (short_code == 0) {
+                break; // found target range
+            }
+            --short_code; // short code approximate
+        }
+    }
+    return (uint64_t)head << 32 | Common::range_reverse(range); // release common code
+}