palaniraja/CMakeLists.txt

## build.sh
mkdir build && cd $_
emcmake cmake ..
make


# now you should have fileProcessor.js and fileProcessor.wasm

# Then run ../index.html (in a local webserver)

## CMakeLists.txt
cmake_minimum_required(VERSION 3.12)
project(fileProcessor)

set(CMAKE_CXX_STANDARD 11)

add_executable(fileProcessor fileProcessor.cpp)

# set_target_properties(fileProcessor PROPERTIES LINK_FLAGS "-s WASM=1 -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]'")
# set_target_properties(fileProcessor PROPERTIES LINK_FLAGS "-s WASM=1 -s EXPORTED_RUNTIME_METHODS='[\"cwrap\"]' -s EXPORTED_FUNCTIONS='[\"_malloc\", \"_free\"]'")
set_target_properties(fileProcessor PROPERTIES LINK_FLAGS "-s WASM=1 -s EXPORTED_RUNTIME_METHODS='[\"cwrap\", \"UTF8ToString\"]' -s EXPORTED_FUNCTIONS='[\"_malloc\", \"_free\"]'")


## fileProcessor.cpp
#ifdef __EMSCRIPTEN__
#include <emscripten/emscripten.h>
#else
#define EMSCRIPTEN_KEEPALIVE
#endif

#include <string>

extern "C" {
    EMSCRIPTEN_KEEPALIVE

    char* processFile(char* fileData, size_t fileSize) {
        // Process the file data here...
        // This is a placeholder - you'd replace this with your actual code.
        std::string result = "Processed file of size: " + std::to_string(fileSize);

        // Allocate memory on the heap for the result string.
        char* heapResult = (char*) malloc(result.size() + 1); // +1 for the null-terminator

        // Copy the result string into the heap memory.
        strcpy(heapResult, result.c_str());

        return heapResult;
    }
}

## index.html
<!DOCTYPE html>
<html>
<head>
    <title>File Processing with WASM</title>
</head>
<body>
    <input type="file" id="fileInput">

    <script type="text/javascript"  src="build/fileProcessor.js"> </script>

    <script>

        Module['onRuntimeInitialized'] = function() {
            console.log("onRuntimeInitialized - called")

            document.getElementById('fileInput').addEventListener('change', function(event) {
                var file = event.target.files[0];
                var reader = new FileReader();
                reader.onload = function() {
                    var arrayBuffer = this.result;
                    var fileData = new Uint8Array(arrayBuffer);

                    // Allocate memory in the WASM module's memory space.
                    var pointer = Module._malloc(fileData.length);

                    // Copy the file data into the WASM module's memory.
                    Module.HEAPU8.set(fileData, pointer);

                    // Call the WASM function.
                    var resultPointer = Module._processFile(pointer, fileData.length);

                    // Get the result string.
                    var result = Module.UTF8ToString(resultPointer);

                    // Log the result.
                    console.log(result);

                    // Free the memory.
                    Module._free(pointer);
                    Module._free(resultPointer);
                };
                reader.readAsArrayBuffer(file);
            });
        }


    </script>


</body>
</html>
	mkdir build && cd $_
	emcmake cmake ..
	make


	# now you should have fileProcessor.js and fileProcessor.wasm

	# Then run ../index.html (in a local webserver)
	cmake_minimum_required(VERSION 3.12)
	project(fileProcessor)

	set(CMAKE_CXX_STANDARD 11)

	add_executable(fileProcessor fileProcessor.cpp)

	# set_target_properties(fileProcessor PROPERTIES LINK_FLAGS "-s WASM=1 -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]'")
	# set_target_properties(fileProcessor PROPERTIES LINK_FLAGS "-s WASM=1 -s EXPORTED_RUNTIME_METHODS='[\"cwrap\"]' -s EXPORTED_FUNCTIONS='[\"_malloc\", \"_free\"]'")
	set_target_properties(fileProcessor PROPERTIES LINK_FLAGS "-s WASM=1 -s EXPORTED_RUNTIME_METHODS='[\"cwrap\", \"UTF8ToString\"]' -s EXPORTED_FUNCTIONS='[\"_malloc\", \"_free\"]'")
	#ifdef __EMSCRIPTEN__
	#include <emscripten/emscripten.h>
	#else
	#define EMSCRIPTEN_KEEPALIVE
	#endif

	#include <string>

	extern "C" {
	EMSCRIPTEN_KEEPALIVE

	char* processFile(char* fileData, size_t fileSize) {
	// Process the file data here...
	// This is a placeholder - you'd replace this with your actual code.
	std::string result = "Processed file of size: " + std::to_string(fileSize);

	// Allocate memory on the heap for the result string.
	char* heapResult = (char*) malloc(result.size() + 1); // +1 for the null-terminator

	// Copy the result string into the heap memory.
	strcpy(heapResult, result.c_str());

	return heapResult;
	}
	}
	<!DOCTYPE html>
	<html>
	<head>
	<title>File Processing with WASM</title>
	</head>
	<body>
	<input type="file" id="fileInput">

	<script type="text/javascript" src="build/fileProcessor.js"> </script>

	<script>

	Module['onRuntimeInitialized'] = function() {
	console.log("onRuntimeInitialized - called")

	document.getElementById('fileInput').addEventListener('change', function(event) {
	var file = event.target.files[0];
	var reader = new FileReader();
	reader.onload = function() {
	var arrayBuffer = this.result;
	var fileData = new Uint8Array(arrayBuffer);

	// Allocate memory in the WASM module's memory space.
	var pointer = Module._malloc(fileData.length);

	// Copy the file data into the WASM module's memory.
	Module.HEAPU8.set(fileData, pointer);

	// Call the WASM function.
	var resultPointer = Module._processFile(pointer, fileData.length);

	// Get the result string.
	var result = Module.UTF8ToString(resultPointer);

	// Log the result.
	console.log(result);

	// Free the memory.
	Module._free(pointer);
	Module._free(resultPointer);
	};
	reader.readAsArrayBuffer(file);
	});
	}



	</script>


	</body>
	</html>