first commit

src/hash.cpp

@@ -0,0 +1,33 @@
+#include "hash.hpp"
+#define XXH_INLINE_ALL
+#include "xxhash.hpp"
+#include <fstream>
+#include <sstream>
+#include <iomanip>
+
+static std::string to_hex64(uint64_t value) {
+    std::ostringstream oss;
+    oss << std::hex << std::setw(16) << std::setfill('0') << value;
+    return oss.str();
+}
+
+std::string hash_data(const std::string& data) {
+    uint64_t h = XXH3_64bits(data.data(), data.size());
+    return to_hex64(h);
+}
+
+std::string hash_file(const std::string& path) {
+    std::ifstream file(path, std::ios::binary);
+    if (!file) return "";
+    XXH64_state_t* state = XXH64_createState();
+    XXH64_reset(state, 0);
+    char buf[4096];
+    while (file) {
+        file.read(buf, sizeof(buf));
+        std::streamsize n = file.gcount();
+        if (n > 0) XXH64_update(state, buf, static_cast<size_t>(n));
+    }
+    uint64_t h = XXH64_digest(state);
+    XXH64_freeState(state);
+    return to_hex64(h);
+}