diff --git a/README.md b/README.md
index 462de64..cfc48e3 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,13 @@
 # hack-assembler
 
-An implementation of a hack assembler in C++.
\ No newline at end of file
+An implementation of a hack assembler in C++.
+
+## Usage
+
+```bash
+g++ -o hack-assembler main.cpp
+cat <input_file.asm> | ./hack-assembler > <output_file.hack>
+```
+
+## License
+This project is under the WTFPL License. See [LICENSE](LICENSE) for details.
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..5071d7e
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,145 @@
+#include <iostream>
+#include <bitset>
+#include <string>
+#include <cctype>
+#include <map>
+
+// Comp map
+const std::map<std::string, std::string> compMap = {
+    {"0",   "0101010"},
+    {"1",   "0111111"},
+    {"-1",  "0111010"},
+    {"D",   "0001100"},
+    {"A",   "0110000"},
+    {"!D",  "0001101"},
+    {"!A",  "0110001"},
+    {"-D",  "0001111"},
+    {"-A",  "0110011"},
+    {"D+1", "0011111"},
+    {"A+1", "0110111"},
+    {"D-1", "0001110"},
+    {"A-1", "0110010"},
+    {"D+A", "0000010"},
+    {"A+D", "0000010"},
+    {"D-A", "0010011"},
+    {"A-D", "0000111"},
+    {"D&A", "0000000"},
+    {"A&D", "0000000"},
+    {"D|A", "0010101"},
+    {"A|D", "0010101"},
+    {"M",   "1110000"},
+    {"!M",  "1110001"},
+    {"-M",  "1110011"},
+    {"M+1", "1110111"},
+    {"M-1", "1110010"},
+    {"D+M", "1000010"},
+    {"D+M", "1000010"},
+    {"D-M", "1010011"},
+    {"M-D", "1000111"},
+    {"D&M", "1000000"},
+    {"M&D", "1000000"},
+    {"D|M", "1010101"},
+    {"M|D", "1010101"}
+};
+
+// dest Map
+const std::map<std::string, std::string> destMap = {
+    {"null", "000"},
+    {"M",    "001"},
+    {"D",    "010"},
+    {"MD",   "011"},
+    {"DM",   "011"},
+    {"A",    "100"},
+    {"AM",   "101"},
+    {"MA",   "101"},
+    {"AD",   "110"},
+    {"DA",   "110"},
+    {"ADM",  "111"},
+    {"AMD",  "111"},
+    {"DAM",  "111"},
+    {"DMA",  "111"},
+    {"MDA",  "111"},
+    {"MAD",  "111"}
+};
+
+
+// jump Map
+const std::map<std::string, std::string> jumpMap = {
+    {"null", "000"},
+    {"JGT",  "001"},
+    {"JEQ",  "010"},
+    {"JGE",  "011"},
+    {"JLT",  "100"},
+    {"JNE",  "101"},
+    {"JLE",  "110"},
+    {"JMP",  "111"}
+};
+
+static inline std::string trim(const std::string &s) {
+    size_t a = s.find_first_not_of(" \t\n\r");
+    if (a == std::string::npos) return "";
+    size_t b = s.find_last_not_of(" \t\n\r");
+    return s.substr(a, b - a + 1);
+}
+
+static inline std::string strip(const std::string &s) {
+    std::string result;
+    for (char c : s) {
+        if (!std::isspace(static_cast<unsigned char>(c))) {
+            result += c;
+        }
+    }
+    return result;
+}
+
+int main() {
+    std::string line;
+    while (std::getline(std::cin, line)) {
+        line = trim(line);
+        if (line.empty()) continue;
+
+        // skip comments
+        if (line[0] == '#' || (line.size() > 1 && line[0] == '/' && line[1] == '/')) continue;
+
+        // A-instruction
+        if (line[0] == '@') {
+            std::string value = line.substr(1);
+            if (value.empty()) continue;
+            try {
+                int intValue = std::stoi(value);
+                std::bitset<16> binaryValue(intValue);
+                std::cout << binaryValue.to_string() << '\n';
+            } catch (...) { continue; }
+        } else { // C-instruction
+            std::string instruction = "111";
+            size_t eqPos = line.find('=');
+            size_t scPos = line.find(';');
+            // comp
+            std::string comp;
+            if (eqPos != std::string::npos) {
+                comp = line.substr(eqPos + 1, scPos - eqPos - 1);
+            } else if (scPos != std::string::npos) {
+                comp = line.substr(0, scPos);
+            } else {
+                comp = line;
+            }
+            comp = strip(comp);
+            auto compIt = compMap.find(comp);
+            if (compIt == compMap.end()) continue;
+            instruction += compIt->second;
+            // dest use use destMap "null" key if not found
+            std::string dest = (eqPos != std::string::npos) ? line.substr(0, eqPos) : "null";
+            dest = strip(dest);
+            auto destIt = destMap.find(dest);
+            instruction += (destIt != destMap.end()) ? destIt->second : destMap.at("null");
+            // jump
+            std::string jump = (scPos != std::string::npos) ? line.substr(scPos + 1) : "null";
+            jump = strip(jump);
+            auto jumpIt = jumpMap.find(jump);
+            instruction += (jumpIt != jumpMap.end()) ? jumpIt->second : jumpMap.at("null");
+            std::cout << instruction << '\n';
+        }
+    }
+    return 0;
+}
+