From 7cdb08746e0bc294dd2cd349c47a3c6cbf65a70d Mon Sep 17 00:00:00 2001
From: Your Name <j@842.be>
Date: Sat, 17 May 2025 09:28:41 +1200
Subject: [PATCH] fix hash - uint64_t

---
 src/generator.cpp | 31 ++++++++++++++++++-------------
 test.sh           |  8 ++++++++
 2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/generator.cpp b/src/generator.cpp
index 40d6676..59a9051 100644
--- a/src/generator.cpp
+++ b/src/generator.cpp
@@ -15,6 +15,16 @@ static std::string sanitize(const std::string& name) {
     return out;
 }
 
+
+static uint64_t fnv1a_64(const void* data, size_t len) {
+    const uint8_t* p = static_cast<const uint8_t*>(data);
+    uint64_t h = 0xcbf29ce484222325ULL;
+    for (size_t i = 0; i < len; ++i)
+        h = (h ^ p[i]) * 0x100000001b3ULL;
+    return h;
+}
+
+
 void generate_file_code(const std::string& source, const std::string& destfolder, bool silent) {
     fs::path src(source);
     fs::path dest(destfolder);
@@ -26,7 +36,7 @@ void generate_file_code(const std::string& source, const std::string& destfolder
     std::ostringstream oss;
     oss << in.rdbuf();
     std::string filedata = oss.str();
-    std::string hash = hash_data(filedata);
+    uint64_t hash = fnv1a_64(filedata.data(), filedata.size());
     // Write HPP
     std::ofstream hpp(dest / hppname);
     hpp << "#pragma once\n#include <string>\nnamespace " << ns << " {\nbool recreate_file(std::string destination_folder);\n}\n";
@@ -65,16 +75,13 @@ static uint64_t fnv1a_64(const void* data, size_t len) {
 bool recreate_file(std::string destination_folder) {
     namespace fs = std::filesystem;
     fs::path outpath = fs::path(destination_folder) / ")cpp" << src.filename().string() << R"cpp(";
-    std::string existing_hash;
+    uint64_t existing_hash;
     if (fs::exists(outpath)) {
         std::ifstream in(outpath, std::ios::binary);
         std::ostringstream oss;
         oss << in.rdbuf();
         std::string data = oss.str();
-        uint64_t h = fnv1a_64(data.data(), data.size());
-        std::ostringstream hex;
-        hex << std::hex << std::setw(16) << std::setfill('0') << h;
-        existing_hash = hex.str();
+        existing_hash = fnv1a_64(data.data(), data.size());
     }
     bool needs_write = !fs::exists(outpath) || existing_hash != file_hash;
     if (needs_write) {
@@ -106,6 +113,7 @@ void walk_dir(const fs::path& dir, F&& f) {
     }
 }
 
+
 void generate_folder_code(const std::string& source, const std::string& destfolder, bool silent) {
     fs::path src(source);
     fs::path dest(destfolder);
@@ -181,7 +189,7 @@ static uint64_t fnv1a_64(const void* data, size_t len) {
         std::ostringstream oss;
         oss << in.rdbuf();
         std::string filedata = oss.str();
-        std::string hash = hash_data(filedata);
+        uint64_t hash = fnv1a_64(filedata.data(), filedata.size());
         std::string rel = fs::relative(file, src).string();
         std::string var = sanitize(rel);
         cpp << "static const unsigned char data_" << var << "[] = {";
@@ -194,7 +202,7 @@ static uint64_t fnv1a_64(const void* data, size_t len) {
         // Reset to decimal format
         cpp << std::dec;
         cpp << "static const size_t len_" << var << " = " << filedata.size() << ";\n";
-        cpp << "static const char* hash_" << var << " = \"" << hash << "\";\n";
+        cpp << "static uint64_t hash_" << var << " = \"" << hash << "\";\n";
         cpp << "static const char* rel_" << var << " = \"" << rel << "\";\n";
     }
     // Write recreate_tree using heredoc style
@@ -209,15 +217,12 @@ bool recreate_tree(std::string destination_folder) {
         cpp << R"cpp(    {
         fs::path outpath = fs::path(destination_folder) / )cpp" << "rel_" << var << R"cpp(;
         fs::create_directories(outpath.parent_path());
-        std::string existing_hash;
+        uint64_t existing_hash;
         if (fs::exists(outpath)) {
             std::ifstream in(outpath, std::ios::binary);
             std::ostringstream oss; oss << in.rdbuf();
             std::string data = oss.str();
-            uint64_t h = fnv1a_64(data.data(), data.size());
-            std::ostringstream hex;
-            hex << std::hex << std::setw(16) << std::setfill('0') << h;
-            existing_hash = hex.str();
+            existing_hash = fnv1a_64(data.data(), data.size());
         }
         bool needs_write = !fs::exists(outpath) || existing_hash != )cpp" << "hash_" << var << R"cpp(;
         if (needs_write) {
diff --git a/test.sh b/test.sh
index ab2293a..fe64865 100755
--- a/test.sh
+++ b/test.sh
@@ -30,5 +30,13 @@ g++ -std=c++17 -I $TEST_DIR -o $TEST_DIR/testexe $TEST_DIR/main.cpp $TEST_DIR/_s
 
 $TEST_DIR/testexe
 
+# second time should be no changes (hash should match)
+$TEST_DIR/testexe
+
+
+# third time just two files changed
+rm $TEST_DIR/temp/generator.cpp
+echo "whee!" >> $TEST_DIR/temp/hash.cpp
+
 $TEST_DIR/testexe