from hardware.hardware import Hardware
from instruction.nop import Nop
from instruction.ri.addiu import Addiu
from instruction.ldst.load import Load
from instruction.ldst.store import Store
from instruction.br.BEQ import Beq
from instruction.rr.addu import Addu
from instruction.j.j import J

class Controller:
    opMap = {
        0x09: Addiu,
        0x20: Load,
        0x28: Store,
        0x04: Beq,
        0x02: J,
    }
    funcMap = {
        0x00: Nop,
        0x21: Addu,
    }

    def __init__(self, hw):
        self.hw = hw

    #获取指令对象
    #输入：
    #   instr为指令编码
    #输出：
    #   instr表示的指令类型的对象
    def getInstrObj(self, instr):
        mask = (1 << 6) - 1
        op = (instr >> 26) & mask
        func = instr & mask

        if op == 0x00:
            if func in Controller.funcMap.keys():
                return Controller.funcMap[func](self.hw)
            else:
                raise Exception('instruction does not exist')
        else:
            if op in Controller.opMap.keys():
                return Controller.opMap[op](self.hw)
            else:
                raise Exception('instruction does not exist')

    #取指令阶段
    #效果：
    #   将即将执行的指令编码写入instr寄存器，pc+4
    def instrFetch(self):
        #从指令存储器中取指令
        pc = self.hw.pc.read()
        instr = self.hw.instrMem.read(pc)
        self.hw.pplReg[1][0].write(instr)

        #pc+4
        self.hw.pc.write(pc + 4)

        return instr

    #无流水线的执行
    #效果：
    #   完整执行一条指令
    def run(self):
        #取指令，获取指令对象
        instr = self.instrFetch()
        instrObj = self.getInstrObj(instr)
        self.hw.globalSync()

        for i in range(len(instrObj.stages)):
            instrObj.stages[i]()
            self.hw.globalSync()