wasm_patch_export.h

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#ifndef YAZE_APP_PLATFORM_WASM_WASM_PATCH_EXPORT_H_
#define YAZE_APP_PLATFORM_WASM_WASM_PATCH_EXPORT_H_
 
#ifdef __EMSCRIPTEN__
 
#include <cstdint>
#include <string>
#include <utility>
#include <vector>
 
#include "absl/status/status.h"
#include "absl/status/statusor.h"
 
namespace yaze {
namespace platform {
 
struct PatchInfo {
  size_t changed_bytes;                                // Total number of changed bytes
  size_t num_regions;                                  // Number of distinct changed regions
  std::vector<std::pair<size_t, size_t>> changed_regions;  // List of (offset, length) pairs
};
 
class WasmPatchExport {
 public:
  static absl::Status ExportBPS(const std::vector<uint8_t>& original,
                                const std::vector<uint8_t>& modified,
                                const std::string& filename);
 
  static absl::Status ExportIPS(const std::vector<uint8_t>& original,
                                const std::vector<uint8_t>& modified,
                                const std::string& filename);
 
  static PatchInfo GetPatchPreview(const std::vector<uint8_t>& original,
                                   const std::vector<uint8_t>& modified);
 
 private:
  // CRC32 calculation
  static uint32_t CalculateCRC32(const std::vector<uint8_t>& data);
  static uint32_t CalculateCRC32(const uint8_t* data, size_t size);
 
  // BPS format helpers
  static void WriteVariableLength(std::vector<uint8_t>& output, uint64_t value);
  static std::vector<uint8_t> GenerateBPSPatch(const std::vector<uint8_t>& source,
                                               const std::vector<uint8_t>& target);
 
  // IPS format helpers
  static void WriteIPS24BitOffset(std::vector<uint8_t>& output, uint32_t offset);
  static void WriteIPS16BitSize(std::vector<uint8_t>& output, uint16_t size);
  static std::vector<uint8_t> GenerateIPSPatch(const std::vector<uint8_t>& source,
                                               const std::vector<uint8_t>& target);
 
  // Common helpers
  static std::vector<std::pair<size_t, size_t>> FindChangedRegions(
      const std::vector<uint8_t>& original,
      const std::vector<uint8_t>& modified);
 
  // Browser download functionality (implemented via EM_JS)
  static absl::Status DownloadPatchFile(const std::string& filename,
                                        const std::vector<uint8_t>& data,
                                        const std::string& mime_type);
};
 
}  // namespace platform
}  // namespace yaze
 
#else  // !__EMSCRIPTEN__
 
// Stub implementation for non-WASM builds
namespace yaze {
namespace platform {
 
struct PatchInfo {
  size_t changed_bytes = 0;
  size_t num_regions = 0;
  std::vector<std::pair<size_t, size_t>> changed_regions;
};
 
class WasmPatchExport {
 public:
  static absl::Status ExportBPS(const std::vector<uint8_t>&,
                                const std::vector<uint8_t>&,
                                const std::string&) {
    return absl::UnimplementedError("Patch export is only available in WASM builds");
  }
 
  static absl::Status ExportIPS(const std::vector<uint8_t>&,
                                const std::vector<uint8_t>&,
                                const std::string&) {
    return absl::UnimplementedError("Patch export is only available in WASM builds");
  }
 
  static PatchInfo GetPatchPreview(const std::vector<uint8_t>&,
                                   const std::vector<uint8_t>&) {
    return PatchInfo{};
  }
};
 
}  // namespace platform
}  // namespace yaze
 
#endif  // __EMSCRIPTEN__
 
#endif  // YAZE_APP_PLATFORM_WASM_WASM_PATCH_EXPORT_H_