Finish

Signed-off-by: Slendi <slendi@socopon.com>

bfl.cpp

@@ -1,18 +1,511 @@
+#include <cassert>
 #include <filesystem>
 #include <fstream>
+#include <optional>
 #include <print>
+#include <span>
 #include <vector>
 
 #define STB_IMAGE_IMPLEMENTATION
 #include "stb_image.h"
 
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+// Helpers
+
+inline void store_le16(std::vector<uint8_t> &buf, uint16_t val) {
+  buf.push_back(static_cast<uint8_t>(val & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 8) & 0xFF));
+}
+
+inline void store_le32(std::vector<uint8_t> &buf, uint32_t val) {
+  buf.push_back(static_cast<uint8_t>(val & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 8) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 16) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 24) & 0xFF));
+}
+
+inline void store_le64(std::vector<uint8_t> &buf, uint64_t val) {
+  buf.push_back(static_cast<uint8_t>(val & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 8) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 16) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 24) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 32) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 40) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 48) & 0xFF));
+  buf.push_back(static_cast<uint8_t>((val >> 56) & 0xFF));
+}
+
+static inline uint16_t read_le16(std::span<const uint8_t> s, size_t off) {
+  return static_cast<uint16_t>(s[off] | (s[off + 1] << 8));
+}
+
+static inline uint32_t read_le32(std::span<const uint8_t> s, size_t off) {
+  return static_cast<uint32_t>(s[off] | (s[off + 1] << 8) | (s[off + 2] << 16) |
+                               (s[off + 3] << 24));
+}
+
+static std::vector<uint8_t> lzss_compress(std::span<const uint8_t> in) {
+  const int W = 4096;
+  const int LA = 18;
+  const int MIN = 3;
+
+  std::vector<uint8_t> out;
+  size_t i = 0;
+
+  while (i < in.size()) {
+    uint8_t flag = 0;
+    size_t flag_pos = out.size();
+    out.push_back(0);
+
+    for (int bit = 0; bit < 8 && i < in.size(); ++bit) {
+      size_t best_len = 0;
+      size_t best_off = 0;
+
+      size_t wnd_start = (i > (size_t)W) ? i - W : 0;
+      size_t max_len = std::min((size_t)LA, in.size() - i);
+
+      for (size_t p = i; p-- > wnd_start;) {
+        size_t l = 0;
+        while (l < max_len && in[p + l] == in[i + l])
+          l++;
+        if (l >= (size_t)MIN && l > best_len) {
+          best_len = l;
+          best_off = i - p;
+          if (best_len == (size_t)LA)
+            break;
+        }
+      }
+
+      if (best_len >= (size_t)MIN && best_off >= 1 && best_off <= 4095) {
+        uint8_t b0 =
+            static_cast<uint8_t>(((best_len - 3) << 4) | (best_off >> 8));
+        uint8_t b1 = static_cast<uint8_t>(best_off & 0xFF);
+        out.push_back(b0);
+        out.push_back(b1);
+        i += best_len;
+      } else {
+        flag |= (1u << bit);
+        out.push_back(in[i]);
+        ++i;
+      }
+    }
+
+    out[flag_pos] = flag;
+  }
+
+  return out;
+}
+
+// "Library"
+
+constexpr uint8_t FLAG_HAS_ALPHA = 0x01;
+constexpr uint8_t FLAG_IMG_RAW = 0x02;  // pre-LZSS image was RAW bitpack
+constexpr uint8_t FLAG_TRA_RAW = 0x04;  // pre-LZSS mask was RAW bitpack
+constexpr uint8_t FLAG_IMG_NOLZ = 0x08; // image stream stored without LZSS
+constexpr uint8_t FLAG_TRA_NOLZ = 0x10; // mask stream stored without LZSS
+
+static std::vector<uint8_t>
+rle_encode_with_transparency(const std::vector<bool> &data, bool initial,
+                             const std::vector<bool> *transparency,
+                             bool allow_trick) {
+  std::vector<uint8_t> out;
+  out.push_back(static_cast<uint8_t>(initial));
+
+  bool state = initial;
+  size_t count = 0;
+  size_t i = 0;
+
+  auto flush_emit = [&](uint8_t n) { out.push_back(n); };
+
+  while (i < data.size()) {
+    bool is_transparent = transparency && (*transparency)[i];
+
+    if (allow_trick && is_transparent) {
+      while (i < data.size() && (*transparency)[i]) {
+        if (count == 255) {
+          flush_emit(255);
+          state = !state;
+          count = 0;
+        }
+        ++count;
+        ++i;
+      }
+      continue;
+    }
+
+    bool bit = data[i];
+    if (bit == state) {
+      ++count;
+      ++i;
+
+      if (count == 255 && i < data.size()) {
+        flush_emit(255);
+        out.push_back(0);
+        count = 0;
+      }
+    } else {
+      flush_emit(static_cast<uint8_t>(count));
+      state = !state;
+      count = 1;
+      ++i;
+    }
+  }
+
+  if (count > 0)
+    flush_emit(static_cast<uint8_t>(count));
+  return out;
+}
+
+static std::vector<uint8_t> lzss_decompress(std::span<const uint8_t> in) {
+  std::vector<uint8_t> out;
+  size_t i = 0;
+
+  while (i < in.size()) {
+    uint8_t flag = in[i++];
+    for (int bit = 0; bit < 8 && i < in.size(); ++bit) {
+      bool is_lit = (flag >> bit) & 1;
+      if (is_lit) {
+        out.push_back(in[i++]);
+      } else {
+        if (i + 1 >= in.size())
+          return out;
+        uint8_t b0 = in[i++];
+        uint8_t b1 = in[i++];
+        size_t len = (b0 >> 4) + 3;
+        size_t off = ((b0 & 0x0F) << 8) | b1; // 1..4095
+
+        if (off == 0 || off > out.size())
+          return out; // invalid
+        size_t src = out.size() - off;
+        for (size_t k = 0; k < len; ++k) {
+          out.push_back(out[src + k]);
+        }
+      }
+    }
+  }
+  return out;
+}
+
+static std::vector<bool> rle_decode(std::span<const uint8_t> in,
+                                    size_t total_bits) {
+  std::vector<bool> out(total_bits, false);
+  if (in.size() < 2)
+    return out;
+
+  bool state = in[0] != 0;
+  size_t produced = 0;
+  size_t j = 1;
+
+  while (produced < total_bits && j < in.size()) {
+    uint8_t n = in[j++];
+
+    if (n == 0) {
+      continue;
+    }
+
+    size_t emit = std::min<size_t>(n, total_bits - produced);
+    for (size_t k = 0; k < emit; ++k)
+      out[produced + k] = state;
+    produced += emit;
+
+    if (j < in.size() && in[j] == 0) {
+      ++j;
+    } else {
+      state = !state;
+    }
+  }
+
+  return out;
+}
+
+static std::vector<bool> raw_decode(std::span<const uint8_t> in,
+                                    size_t total_bits) {
+  std::vector<bool> out(total_bits, false);
+  for (size_t i = 0; i < total_bits; ++i) {
+    uint8_t byte = (i / 8 < in.size()) ? in[i / 8] : 0;
+    out[i] = ((byte >> (i % 8)) & 1) != 0;
+  }
+  return out;
+}
+
 struct Bitmap {
-  int width, height;
-  bool compressed{};
+  uint16_t width{}, height{};
   std::vector<bool> image_data;
-  std::vector<bool> transparency_data;
+  std::optional<std::vector<bool>> transparency_data;
+
+  auto to_rgba() -> std::vector<uint32_t>;
+  auto encode() -> std::vector<uint8_t> {
+    auto const raw_encode =
+        [](std::vector<bool> const &data) -> std::vector<uint8_t> {
+      std::vector<uint8_t> bytes((data.size() + 7) / 8, 0);
+      for (size_t i = 0; i < data.size(); ++i) {
+        if (data[i])
+          bytes[i / 8] |= (1u << (i % 8));
+      }
+      return bytes;
+    };
+
+    std::vector<uint8_t> ret;
+
+    // header
+    ret.push_back('B');
+    ret.push_back('F');
+    ret.push_back('L');
+    store_le16(ret, width);
+    store_le16(ret, height);
+
+    auto encode_best = [&](std::vector<bool> const &data, bool &raw_flag,
+                           bool allow_trick) {
+      const std::vector<bool> *mask =
+          transparency_data ? &(*transparency_data) : nullptr;
+
+      auto init_false =
+          rle_encode_with_transparency(data, false, mask, allow_trick);
+      auto init_true =
+          rle_encode_with_transparency(data, true, mask, allow_trick);
+
+      std::vector<uint8_t> result = (init_false.size() <= init_true.size())
+                                        ? std::move(init_false)
+                                        : std::move(init_true);
+
+      if (result.size() * 8 > data.size()) {
+        result = raw_encode(data);
+        raw_flag = true;
+      }
+      return result;
+    };
+
+    std::vector<uint8_t> image_bytes, trans_bytes;
+    bool image_raw = false, trans_raw = false;
+
+    image_bytes =
+        encode_best(image_data, image_raw, transparency_data.has_value());
+    if (transparency_data) {
+      trans_bytes = encode_best(*transparency_data, trans_raw, false);
+    }
+
+    bool img_no_lz = false, tra_no_lz = false;
+
+    std::vector<uint8_t> img_stream_lz = lzss_compress(image_bytes);
+    std::vector<uint8_t> img_stream =
+        (img_stream_lz.size() < image_bytes.size())
+            ? std::move(img_stream_lz)
+            : (img_no_lz = true, image_bytes);
+
+    std::vector<uint8_t> tra_stream;
+    if (!trans_bytes.empty()) {
+      auto tra_stream_lz = lzss_compress(trans_bytes);
+      tra_stream = (tra_stream_lz.size() < trans_bytes.size())
+                       ? std::move(tra_stream_lz)
+                       : (tra_no_lz = true, trans_bytes);
+    }
+
+    // flags
+    uint8_t flags = 0;
+    if (transparency_data)
+      flags |= FLAG_HAS_ALPHA;
+    if (image_raw)
+      flags |= FLAG_IMG_RAW;
+    if (trans_raw)
+      flags |= FLAG_TRA_RAW;
+    if (img_no_lz)
+      flags |= FLAG_IMG_NOLZ;
+    if (tra_no_lz)
+      flags |= FLAG_TRA_NOLZ;
+    ret.push_back(flags);
+
+    store_le32(ret, static_cast<uint32_t>(img_stream.size()));
+    store_le32(ret, static_cast<uint32_t>(tra_stream.size()));
+
+    // payload
+    ret.insert(ret.end(), img_stream.begin(), img_stream.end());
+    ret.insert(ret.end(), tra_stream.begin(), tra_stream.end());
+
+    return ret;
+  }
+
+  static auto from_rgba(std::span<uint32_t const> const &data, int width,
+                        int height) -> Bitmap;
+  static auto decode(std::span<uint8_t const> const &data) -> Bitmap;
 };
 
+auto Bitmap::decode(std::span<uint8_t const> const &data) -> Bitmap {
+  Bitmap bm{};
+
+  if (data.size() < 3 + 2 + 2 + 1 + 4 + 4)
+    return bm;
+  if (!(data[0] == 'B' && data[1] == 'F' && data[2] == 'L'))
+    return bm;
+
+  size_t off = 3;
+  uint16_t w = read_le16(data, off);
+  off += 2;
+  uint16_t h = read_le16(data, off);
+  off += 2;
+
+  uint8_t flags = data[off++];
+
+  uint32_t img_c_len = read_le32(data, off);
+  off += 4;
+  uint32_t tra_c_len = read_le32(data, off);
+  off += 4;
+
+  if (off + img_c_len > data.size())
+    return bm;
+  if (off + img_c_len + tra_c_len > data.size())
+    return bm;
+
+  auto img_c = data.subspan(off, img_c_len);
+  off += img_c_len;
+  auto tra_c = data.subspan(off, tra_c_len);
+
+  bool has_alpha = (flags & FLAG_HAS_ALPHA) != 0;
+  bool img_was_raw = (flags & FLAG_IMG_RAW) != 0;
+  bool tra_was_raw = (flags & FLAG_TRA_RAW) != 0;
+  bool img_no_lz = (flags & FLAG_IMG_NOLZ) != 0;
+  bool tra_no_lz = (flags & FLAG_TRA_NOLZ) != 0;
+
+  std::vector<uint8_t> img_stream =
+      img_no_lz ? std::vector<uint8_t>(img_c.begin(), img_c.end())
+                : lzss_decompress(img_c);
+
+  std::vector<uint8_t> tra_stream =
+      (has_alpha ? (tra_no_lz ? std::vector<uint8_t>(tra_c.begin(), tra_c.end())
+                              : lzss_decompress(tra_c))
+                 : std::vector<uint8_t>{});
+
+  size_t total_bits = static_cast<size_t>(w) * static_cast<size_t>(h);
+
+  std::vector<bool> img_bits = img_was_raw ? raw_decode(img_stream, total_bits)
+                                           : rle_decode(img_stream, total_bits);
+
+  std::optional<std::vector<bool>> tra_bits;
+  if (has_alpha) {
+    tra_bits = (tra_was_raw ? raw_decode(tra_stream, total_bits)
+                            : rle_decode(tra_stream, total_bits));
+  }
+
+  bm.width = w;
+  bm.height = h;
+  bm.image_data = std::move(img_bits);
+  bm.transparency_data = std::move(tra_bits);
+  return bm;
+}
+
+auto Bitmap::from_rgba(std::span<uint32_t const> const &data, int w, int h)
+    -> Bitmap {
+  assert(w > 0 && h > 0);
+  assert(static_cast<int>(data.size()) == w * h);
+
+  Bitmap bm;
+  bm.width = w;
+  bm.height = h;
+  bm.image_data.resize(static_cast<size_t>(w) * static_cast<size_t>(h));
+  bm.transparency_data = std::vector<bool>{};
+  bm.transparency_data->resize(static_cast<size_t>(w) * static_cast<size_t>(h));
+
+  for (size_t i = 0; i < data.size(); ++i) {
+    uint32_t px = data[i];
+
+    // little-endian: 0xAABBGGRR
+    uint8_t r = static_cast<uint8_t>((px >> 0) & 0xFF);
+    uint8_t g = static_cast<uint8_t>((px >> 8) & 0xFF);
+    uint8_t b = static_cast<uint8_t>((px >> 16) & 0xFF);
+    uint8_t a = static_cast<uint8_t>((px >> 24) & 0xFF);
+
+    bool is_white = (r == 255 && g == 255 && b == 255 && a != 0);
+    bool is_black = (r == 0 && g == 0 && b == 0 && a != 0);
+
+    bool is_transparent = (!is_white && !is_black) || (a == 0);
+
+    (*bm.transparency_data)[i] = is_transparent;
+    bm.image_data[i] = is_white;
+  }
+
+  return bm;
+}
+
+auto Bitmap::to_rgba() -> std::vector<uint32_t> {
+  std::vector<uint32_t> out;
+  out.resize(static_cast<size_t>(width) * static_cast<size_t>(height));
+
+  auto make_rgba = [](uint8_t r, uint8_t g, uint8_t b, uint8_t a) -> uint32_t {
+    return (static_cast<uint32_t>(r) << 0) | (static_cast<uint32_t>(g) << 8) |
+           (static_cast<uint32_t>(b) << 16) | (static_cast<uint32_t>(a) << 24);
+  };
+
+  for (size_t i = 0; i < out.size(); ++i) {
+    if ((transparency_data && i >= transparency_data->size()) ||
+        i >= image_data.size()) {
+      out[i] = make_rgba(0, 0, 0, 0); // safety
+      continue;
+    }
+
+    if (transparency_data && (*transparency_data)[i]) {
+      out[i] = make_rgba(0, 0, 0, 0);
+    } else {
+      if (image_data[i]) {
+        out[i] = make_rgba(255, 255, 255, 255);
+      } else {
+        out[i] = make_rgba(0, 0, 0, 255);
+      }
+    }
+  }
+
+  return out;
+}
+
+struct BFLHeader {
+  uint16_t w{};
+  uint16_t h{};
+  uint8_t flags{};
+  uint32_t img_len{};
+  uint32_t tra_len{};
+};
+
+static bool parse_bfl_header(std::span<const uint8_t> data, BFLHeader &hdr) {
+  // minimal header: "BFL" + w + h + flags + lenI + lenT
+  if (data.size() < 3 + 2 + 2 + 1 + 4 + 4)
+    return false;
+  if (!(data[0] == 'B' && data[1] == 'F' && data[2] == 'L'))
+    return false;
+
+  size_t off = 3;
+  hdr.w = read_le16(data, off);
+  off += 2;
+  hdr.h = read_le16(data, off);
+  off += 2;
+  hdr.flags = data[off++];
+  hdr.img_len = read_le32(data, off);
+  off += 4;
+  hdr.tra_len = read_le32(data, off);
+  off += 4;
+
+  if (off + hdr.img_len > data.size())
+    return false;
+  if (off + hdr.img_len + hdr.tra_len > data.size())
+    return false;
+  return true;
+}
+
+static void print_bfl_header(BFLHeader const &h) {
+  std::println("BFL header:");
+  std::println("  width       : {}", h.w);
+  std::println("  height      : {}", h.h);
+  std::println("  flags (hex) : 0x{:02X}", h.flags);
+  std::println("    has_alpha : {}", (h.flags & FLAG_HAS_ALPHA) ? "yes" : "no");
+  std::println("    img_raw   : {}", (h.flags & FLAG_IMG_RAW) ? "yes" : "no");
+  std::println("    tra_raw   : {}", (h.flags & FLAG_TRA_RAW) ? "yes" : "no");
+  std::println("    img_no_lz : {}", (h.flags & FLAG_IMG_NOLZ) ? "yes" : "no");
+  std::println("    tra_no_lz : {}", (h.flags & FLAG_TRA_NOLZ) ? "yes" : "no");
+  std::println("  image bytes : {}", h.img_len);
+  std::println("  alpha bytes : {}", h.tra_len);
+}
+
+// CLI
+
 auto read_entire_file(std::filesystem::path const &path)
     -> std::vector<uint8_t> {
   std::ifstream stream(path, std::ios::in | std::ios::binary);
@@ -22,18 +515,73 @@ auto read_entire_file(std::filesystem::path const &path)
 }
 
 auto write_entire_file(std::filesystem::path const &path,
-                       std::span<uint8_t> const &data) -> void {
+                       std::span<uint8_t const> const &data) -> void {
   std::ofstream stream(path, std::ios::out | std::ios::binary);
-  stream.write(reinterpret_cast<char *>(data.data()), data.size());
+  stream.write(reinterpret_cast<char const *>(data.data()), data.size());
 }
 
 auto main(int const argc, char const *argv[]) -> int {
-  if (argc != 2) {
-    std::println(stderr, "Usage: {} <file>", argv[0]);
+  if (argc < 2) {
+    std::println(stderr,
+                 "Usage:\n"
+                 "  {} <input> <output>\n"
+                 "  {} header <file.bfl>",
+                 argv[0], argv[0]);
     return 1;
   }
 
+  if (argc == 3 && std::string_view(argv[1]) == "header") {
+    std::filesystem::path filepath{argv[2]};
+    auto bytes = read_entire_file(filepath);
+    BFLHeader hdr{};
+    if (!parse_bfl_header(bytes, hdr)) {
+      std::println(stderr, "Invalid or truncated BFL: {}", filepath.string());
+      return 2;
+    }
+    print_bfl_header(hdr);
+    return 0;
+  }
+
+  if (argc != 3) {
+    std::println(stderr,
+                 "Usage:\n"
+                 "  {} <input> <output>\n"
+                 "  {} header <file.bfl>",
+                 argv[0], argv[0]);
+    return 1;
+  }
+
+  Bitmap input;
+
+  std::filesystem::path output_filepath{argv[2]};
   std::filesystem::path filepath{argv[1]};
   if (filepath.extension() == ".bfl") {
+    input = Bitmap::decode(read_entire_file(filepath));
+  } else {
+    int width, height, comp;
+    unsigned char *raw_data =
+        stbi_load(filepath.string().c_str(), &width, &height, &comp, 4);
+    if (!raw_data) {
+      std::println(stderr, "stbi_load failed on {}", filepath.string());
+      return 1;
+    }
+
+    std::span<uint32_t const> data{reinterpret_cast<uint32_t const *>(raw_data),
+                                   static_cast<size_t>(width) *
+                                       static_cast<size_t>(height)};
+    input = Bitmap::from_rgba(data, width, height);
+
+    stbi_image_free(raw_data);
   }
+
+  if (output_filepath.extension() == ".bfl") {
+    auto const input_bin = input.encode();
+    std::span<uint8_t const> d{input_bin.data(), input_bin.size()};
+    write_entire_file(output_filepath, d);
+  } else {
+    auto rgba = input.to_rgba();
+    stbi_write_png(output_filepath.string().c_str(), input.width, input.height,
+                   4, rgba.data(), input.width * 4);
+  }
+  return 0;
 }