From 9c925923983c46cab0aaac1a4fe553a05fd04626 Mon Sep 17 00:00:00 2001
From: lzwdgc <lzwdgc@gmail.com>
Date: Tue, 10 Jan 2023 17:31:26 +0300
Subject: [PATCH] [unpaker2] RLEW decompression.

---
 src/unpaker2/unpaker2.cpp | 89 ++++++++++++++++++++++++++++++++-------
 1 file changed, 74 insertions(+), 15 deletions(-)

diff --git a/src/unpaker2/unpaker2.cpp b/src/unpaker2/unpaker2.cpp
index 02c477e..3f96ddd 100644
--- a/src/unpaker2/unpaker2.cpp
+++ b/src/unpaker2/unpaker2.cpp
@@ -37,8 +37,6 @@
 
 using namespace std;
 
-constexpr auto supported_block_size = 32768;
-
 #pragma pack(push, 1)
 struct pak {
     uint32_t magic;
@@ -85,17 +83,46 @@ struct stream {
     }
 };
 
+
+void decode_rle(const short *input, const int size, short *&output) {
+    if (size < 2)
+        return;
+
+    // input ptr, also rle_indicator
+    const auto rle_indicator = input++;
+    while (1) {
+        auto c = *input++;
+        if ((c & 0xFF00) != (*rle_indicator << 8))
+            *output++ = c;
+        else {
+            uint32_t count = (uint8_t)c;
+            if (count == (*rle_indicator << 8) + 255)
+                *output++ = c; // insert indicator byte itself
+            else {
+                count += 3;
+                for (int i = 0; i < count / 2; i++) {
+                    *output++ = *input;
+                    *output++ = *input;
+                }
+                for (int i = 0; i < ((count / 2) & 1); i++) {
+                    *output++ = *input;
+                }
+            }
+        }
+
+        if (input >= rle_indicator + size)
+            return;
+    }
+}
+
 void unpack_file(path fn) {
     primitives::templates2::mmap_file<uint8_t> f{fn};
     stream s{f};
     pak p = s;
-    if (p.block_size != supported_block_size) {
-        throw std::runtime_error{"block size mismatch"};
-    }
     auto descs = s.span<file_description>(p.n_files);
     auto segments = s.span<segment>(p.n_blocks);
     std::vector<uint8_t> bbb;
-    bbb.resize((segments.size() + 1) * supported_block_size);
+    bbb.resize((segments.size() + 1) * p.block_size * 4);
     auto pp = bbb.data();
     for (auto &&seg : segments) {
         s.p = f.p + seg.offset;
@@ -116,19 +143,51 @@ void unpack_file(path fn) {
             break;
         }
         case segment::decode_algorithm::rlew: {
+            /*short *pps = (short*)pp;
+            decode_rle((short*)s.p, len, pps);
+            pp = (uint8_t*)pps;
+            break;*/
             auto base = s.p;
             uint16_t flag = s;
-            uint32_t outlen = 0;
             while (s.p < base + len) {
-                uint8_t w = s;
-                if (w == 0xfe && (*(uint8_t*)s.p) == flag) {
-                    uint8_t w1 = s;
-                    auto cntr = 0x20e;
-                    uint8_t w2 = s;
-                    while (cntr--) {
+                uint16_t w = s;
+                if ((w & 0xFF00) == (flag << 8)) {
+                    uint16_t count = (uint8_t)w;
+                    if (count == 0xff) {
+                        uint16_t w2 = s;
+                        *(decltype(w2) *)pp = w2;
+                        pp += sizeof(w2);
+                        continue;
+                    }
+                    if (count == (flag << 8) + 255) {
+                        throw std::runtime_error{"untested branch"};
+                        *(decltype(w) *)pp = w;
+                        pp += sizeof(w);
+                        continue;
+                    }
+
+
+                    uint16_t w2 = s;
+                    count += 3;
+
+                    while (count--) {
                         *(decltype(w2)*)pp = w2;
                         pp += sizeof(w2);
                     }
+
+                    /*
+                    *
+                    for (int i = 0; i < count / 2; i++) {
+                        *(decltype(w) *)pp = w2;
+                        pp += sizeof(w2);
+
+                        *(decltype(w) *)pp = w2;
+                        pp += sizeof(w2);
+                    }
+                    for (int i = 0; i < ((count / 2) & 1); i++) {
+                        *(decltype(w) *)pp = w2;
+                        pp += sizeof(w2);
+                    }*/
                 } else {
                     *(decltype(w)*)pp = w;
                     pp += sizeof(w);
@@ -143,9 +202,9 @@ void unpack_file(path fn) {
             strm.next_in = s.p;
             strm.avail_in = len;
             strm.next_out = pp;
-            strm.avail_out = 1'000'000;
+            strm.avail_out = p.block_size;
 
-            auto r = lzma_auto_decoder(&strm, 1'000'000'000, flags);
+            auto r = lzma_lzip_decoder(&strm, 10'000'000, flags);
             if (r != LZMA_OK) {
                 throw std::runtime_error{"lzma error"};
             }