alu.c

/**
 *  LC-3 Simulator
 *  Final Project (Project #6)
 *  TCSS 372 - Computer Architecture
 *  Spring 2018
 * 
 *  ALU Module File
 * 
 *  This is a simulator of the LC-3 (Little Computer) machine using an 
 *  object-oriented approach in C. The simulator includes all standard LC-3 
 *  functionality based on the finite state machine approach and the corresponding
 *  opcode tables for the machine, with an additional push-pop stack feature utilized 
 *  on the previously reserved (1101) opcode.
 * 
 *  Group Members:
 *  Michael Fulton
 *  Enoch Chan
 *  Logan Stafford
 * 
 *  Base Code Contributors:
 *  Sam Brendel
 *  Michael Josten
 *  Sam Anderson
 *  Tyler Schupack  
 */

#include "global.h"
#include "slc3.h"
#include <stdlib.h>

typedef struct alu_t {
    word_t sr1;
    word_t sr2;
    word_t result;
} alu_t, *alu_p;

/** Sets the ALU fields to default values */
void initialize_alu(alu_p);

/** Allocates and initializes a new ALU module */
alu_p alu_create() {
    alu_p alu = calloc(1, sizeof(alu_t));
    initialize_alu(alu);
    return alu;
}

/** Reinitializes the ALU without reallocation */
void alu_reset(alu_p alu) { initialize_alu(alu); }

/** Deallocates the ALU */
void alu_destroy(alu_p alu) { free(alu); }

/** Takes a snapshot of the ALU data for debugging or display purposes */
const alu_snapshot_t alu_get_snapshot(alu_p alu) {
    alu_snapshot_t snapshot;
    snapshot.a = alu->sr1;
    snapshot.b = alu->sr2;
    snapshot.result = alu->result;
    return snapshot;
}

/** Load ALU source register 1 */
void alu_load_sr1(alu_p alu, word_t data) { alu->sr1 = data; }

/** Load ALU source register 2 */
void alu_load_sr2(alu_p alu, word_t data) { alu->sr2 = data; }

/** Fetch the result from ALU */
word_t alu_fetch_result(alu_p alu) { return alu->result; }

/** Execute ADD operation on loaded SR1 and SR2 values */
void alu_add(alu_p alu) { alu->result = alu->sr1 + alu->sr2; }

/** Execute AND operation on loaded SR1 and SR2 values. Note: "and" is a protected keyword in C
 * so we'll use "and_op" here */
void alu_and(alu_p alu) { alu->result = alu->sr1 & alu->sr2; }

/** Execute NOT operation on loaded SR1 value */
void alu_not(alu_p alu) { alu->result = ~alu->sr1; }

/** Sets the ALU fields to default values */
void initialize_alu(alu_p alu) {
    alu->sr1 = 0;
    alu->sr2 = 0;
    alu->result = 0;
}