riscv32isimulator/code/alu.py

from binandint import *


def alu(a, b, alu_ctrl):  # a,b为两个运算数，alu_ctrl为控制信号，返回运算结果result与是否为0 zero
    signed = a-b
    if alu_ctrl == '00000':  # add,jalr
        alu_result = a+b
    elif alu_ctrl == '00001':  # sub
        alu_result = a-b
    elif alu_ctrl == '00010':  # or
        alu_result = a | b
    elif alu_ctrl == '00011':  # and
        alu_result = a & b
    elif alu_ctrl == '00100':  # slt
        if(signed >= 0):
            alu_result = 0
        else:
            alu_result = 1
    elif alu_ctrl == '00101':  # beq
        if a == b:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '00110':  # bne
        if a != b:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '00111':  # blt
        if a < b:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '01000':  # bge
        if a >= b:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '01001':
        if a < 0:
            ua = a+2**32
        else:
            ua = a
        if b < 0:
            ub = b+2**32
        else:
            ub = b
        if ua < ub:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '01010':
        if a < 0:
            ua = a+2**32
        else:
            ua = a
        if b < 0:
            ub = b+2**32
        else:
            ub = b
        if ua >= ub:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '01011':
        alu_result = 1
    elif alu_ctrl == '01100':
        alu_result = a ^ b
    elif alu_ctrl == '01101':
        alu_result = a << b
    elif alu_ctrl == '01110':
        if a < 0:
            ua = a+2**32
        else:
            ua = a
        if b < 0:
            ub = b+2**32
        else:
            ub = b
        if ua <= ub:
            alu_result = 1
        else:
            alu_result = 0
    elif alu_ctrl == '01111':
        if a < 0:
            ua = a+2**32
        else:
            ua = a
        alu_result = a >> b
    elif alu_ctrl == '10000':
        alu_result = a >> b
    else:
        alu_result = 0
    return alu_result