Update 'cordiceps.cpp'

It now handle input size correctly

cordiceps.cpp

@@ -1,6 +1,6 @@
 /*
-cmake_minimum_required(VERSION 3.28)
-project(codiceps)
+cmake_minimum_required(VERSION 3.27)
+project(cordiceps)
 
 set(CMAKE_CXX_STANDARD 23)
 
@@ -14,8 +14,8 @@ FetchContent_Declare(
 
 FetchContent_MakeAvailable(raylib)
 
-add_executable(codiceps codiceps.cpp)
-target_link_libraries(codiceps PUBLIC raylib_static)
+add_executable(cordiceps cordiceps.cpp)
+target_link_libraries(cordiceps PUBLIC raylib_static)
 */
 
 #include <ranges>
@@ -24,6 +24,9 @@ target_link_libraries(codiceps PUBLIC raylib_static)
 #include <sstream>
 #include <vector>
 #include <cassert>
+#include <cstdint>
+#include <bit>
+#include <bitset>
 #include "raylib.h"
 
 std::string slurp(const char* filename) {
@@ -50,13 +53,20 @@ std::vector to_bits(std::string str) {
 
 std::string from_bits(std::vector<bool> data) {
     std::string d;
-    for(auto composite : data | std::views::chunk(8)) {
+	std::bitset<32> size_bits;
+	for(int idx = 0; idx < 32; ++idx) size_bits[idx] = data[idx];
+	uint32_t size = size_bits.to_ulong();
+	if(std::endian::native == std::endian::little) size = std::byteswap(size);
+	
+    for(auto composite : data | std::views::drop(32) | std::views::chunk(8)) {
         char c = 0;
         for(auto b : composite) {
             c *= 2;
             c += b;
         }
         d.push_back(c);
+		size--;
+	    if(size == 0) return d;
     }
     return d;
 }
@@ -64,9 +74,18 @@ std::string from_bits(std::vector data) {
 void encode(const char* pic, const char* data_source) {
     auto image = LoadImage(pic);
     auto raw_data = slurp(data_source);
+	uint32_t size = raw_data.size();
+	if(std::endian::native == std::endian::little) size = std::byteswap(size);
+	std::bitset<32> size_bits;
+	size_bits = size;
     std::vector<bool> raw_bits = to_bits(raw_data);
     assert(raw_bits.size() % 8 == 0);
     assert(raw_bits.size() / 8 == raw_data.size());
+	std::vector<bool> data;
+	
+	for(int idx = 0; idx < 32; ++idx) data.push_back(size_bits[idx]);
+	data.insert(data.end(), raw_bits.begin(), raw_bits.end());
+	
     size_t idx = 0;
     for(auto j : std::ranges::iota_view(0, image.height)) {
         for(auto i : std::ranges::iota_view(0, image.width)) {
@@ -74,18 +93,18 @@ void encode(const char* pic, const char* data_source) {
             c.r ^= c.r & 1;
             c.g ^= c.g & 1;
             c.b ^= c.b & 1;
-            c.r += idx < raw_bits.size() ? raw_bits[idx] : 0; idx++;
-            c.g += idx < raw_bits.size() ? raw_bits[idx] : 0; idx++;
-            c.b += idx < raw_bits.size() ? raw_bits[idx] : 0; idx++;
+            c.r += idx < data.size() ? data[idx] : 0; idx++;
+            c.g += idx < data.size() ? data[idx] : 0; idx++;
+            c.b += idx < data.size() ? data[idx] : 0; idx++;
             ImageDrawPixel(&image, i, j, c);
         }
     }
     ExportImage(image, pic);
     UnloadImage(image);
     if(raw_bits.size() > idx) {
-        std::cout << "\x1b[1;31mWritten bits: " << raw_bits.size() << "/" << idx << std::endl;
+        std::cout << "\x1b[1;31mWritten bits: " << data.size() << "/" << idx << std::endl;
     } else {
-        std::cout << "\x1b[1;32mWritten bits: " << raw_bits.size() << "/" << idx << std::endl;
+        std::cout << "\x1b[1;32mWritten bits: " << data.size() << "/" << idx << std::endl;
     }
 }
 
@@ -115,4 +134,4 @@ int main(int argc, char** argv) {
         decode(argv[1]);
     }
     return 0;
-}
+}