/** Reset all of the control signals (after each instruction execution in Stage 5) */
public static void reset_control_signals() {
cpu.c_reg_address_A = 0;
cpu.c_reg_address_B = 0;
cpu.c_reg_address_C = 0;
cpu.c_mux_B_select = 0;
cpu.c_mux_C_select = 0;
cpu.c_mux_Y_select = 0;
cpu.c_RF_write = 0;
cpu.c_condition_signal = 0;
cpu.c_ALU_op = 0;
cpu.RA = 0;
cpu.RB = 0;
cpu.RM = 0;
cpu.RY = 0;
cpu.RZ = 0;
}
/** ALU - Stage 3 */
public static void stage3_execute() throws IOException {
String binary_rep = pad_binary(Integer.toBinaryString(cpu.IR), 32);
String op_code = (String) binary_rep.subSequence(binary_rep.length() - 6, binary_rep.length());
int immediate_value = 0;
if (op_code.equals(definitions.STW)) // If the operation is a STW (store)
{
String imm_val = binary_rep.substring(10, 26);
immediate_value = calc_imm_val(imm_val); // Get the immediate value
cpu.RZ =
ALU(cpu.c_ALU_op, cpu.RA, immediate_value); // RZ = ALU result from RA and immediate value
cpu.RM = cpu.RB; // RM = RB
} else // If the operation isn't a store
{
if (cpu.c_mux_B_select == 0) // If mux_B = 0 then use RB
{
cpu.RZ = ALU(cpu.c_ALU_op, cpu.RA, cpu.RB); // Set RZ = ALU result from RA and RB
} else if (cpu.c_mux_B_select == 1) // If mux_B = 1 then use immediate value
{
String imm_val = binary_rep.substring(10, 26);
immediate_value = calc_imm_val(imm_val); // Get the immediate value
cpu.RZ =
ALU(
cpu.c_ALU_op,
cpu.RA,
immediate_value); // RZ = ALU result from RA and immediate value
}
if (cpu.c_condition_signal == 1) // If the condition signal is set then condition passed
{
String imm_val = "";
if (op_code.equals(definitions.BR)) // If the condition is BR (branch)
{
imm_val = binary_rep.substring(0, 26); // Get the immediate value (B-Type)
} else {
imm_val = binary_rep.substring(10, 26); // Get the immediate value (I-Type)
}
short imm_value = (short) Integer.parseInt(imm_val, 2);
immediate_value = imm_value;
cpu.R[15] = cpu.R[15] + immediate_value; // Update the program counter (PC)
}
}
}
