feat: SnowVM 支持 S_AND

src/main/java/org/jcnc/snow/vm/commands/bitwise/short16/SAndCommand.java

@@ -0,0 +1,56 @@
+package org.jcnc.snow.vm.commands.bitwise.short16;
+
+import org.jcnc.snow.vm.interfaces.Command;
+import org.jcnc.snow.vm.module.CallStack;
+import org.jcnc.snow.vm.module.LocalVariableStore;
+import org.jcnc.snow.vm.module.OperandStack;
+
+/**
+ * The SAndCommand class implements the {@link Command} interface and represents the short16 bitwise AND (`&`) operation command.
+ * This class performs a short16 bitwise AND operation in the virtual machine by popping the top two values from the stack,
+ * computing their short16 bitwise AND operation, and then pushing the result back onto the stack. It is a basic operation command within the virtual machine.
+ *
+ * <p>Specific behavior:</p>
+ * <ul>
+ *     <li>Pops two operands from the virtual machine stack.</li>
+ *     <li>Performs the short16 bitwise AND (`&`) operation.</li>
+ *     <li>Pushes the result back onto the virtual machine stack.</li>
+ * </ul>
+ */
+public class SAndCommand implements Command {
+    /**
+     * Default constructor for creating an instance of {@code SAndCommand}.
+     * This constructor is empty as no specific initialization is required.
+     */
+    public SAndCommand() {
+        // Empty constructor
+    }
+
+    /**
+     * Executes the virtual machine instruction's operation.
+     *
+     * @param parts              The array of instruction parameters, which usually includes the operator and related arguments.
+     * @param currentPC          The current program counter-value, indicating the address of the instruction being executed.
+     * @param operandStack       The virtual machine's operand stack manager, responsible for pushing and popping values.
+     * @param localVariableStore The local variable store, typically used to manage method-local variables.
+     * @param callStack          The virtual machine's call stack, used for managing method calls and returns.
+     * @return The updated program counter-value, typically `currentPC + 1` unless a control flow instruction is executed.
+     * @throws IllegalStateException if there are not enough operands on the stack to perform the operation.
+     */
+    @Override
+    public int execute(String[] parts, int currentPC, OperandStack operandStack, LocalVariableStore localVariableStore, CallStack callStack) {
+        // Ensure the stack has at least two operands
+        if (operandStack.size() < 2) {
+            throw new IllegalStateException("Not enough operands on the stack for SAND operation.");
+        }
+
+        // Pop the top two operands from the stack
+        final short b = (short) operandStack.pop();
+        final short a = (short) operandStack.pop();
+
+        // Perform the short16 bitwise AND operation and push the result back onto the stack
+        operandStack.push(a & b);
+
+        return currentPC + 1;
+    }
+}