// Sets valC and byte0 to byte7 for printReg. Only used by 9 or 10 byte instructions.
void setValC_and_bytes(int numBytesInInstr) {
int PC_offset = numBytesInInstr - 8;
valCValid = 1;
valC = getValC(PC_offset);
b0 = instrBuffer[PC_offset];
b1 = instrBuffer[PC_offset + 1];
b2 = instrBuffer[PC_offset + 2];
b3 = instrBuffer[PC_offset + 3];
b4 = instrBuffer[PC_offset + 4];
b5 = instrBuffer[PC_offset + 5];
b6 = instrBuffer[PC_offset + 6];
b7 = instrBuffer[PC_offset + 7];
}
// Function: fetchStage()
// Description: Stuff
// Params: none
// Returns: nothing
// Modifies: yo momma
//void fetchStage(){
void fetchStage(forwardType forward){
//what address should instruction be fetched at
unsigned int f_pc;
if((forward.M_icode == JXX) && !forward.M_Cnd)
f_pc = forward.M_valA;
else if(forward.W_icode == RET)
f_pc = forward.W_valM;
else
f_pc = F.predPC;
bool memError= false;
unsigned int tempByte = getByte(f_pc, &memError);
unsigned int f_ifun;
unsigned int f_icode;
//determine icode and ifun
if(memError){
f_ifun = FNONE;
f_icode = NOP;
}
else{
f_ifun = getBits(0,3, tempByte);
f_icode = getBits(4,7, tempByte);
}
//is instruction valid
bool instr_valid = instrValid(f_icode);
//determine status code for fetched instruction
unsigned int f_stat;
if(memError) f_stat = SADR;
else if(!instr_valid) f_stat = SINS;
else if(f_icode==HALT) f_stat = SHLT;
else f_stat = SAOK;
//does fetched instruction require a register_id byte?
unsigned int rA;
unsigned int rB;
bool needRId = needRegId(f_icode);
if(needRId)
{
unsigned int rByte = getByte(f_pc+1, &memError);
rA = getBits(4, 7, rByte);
rB = getBits(0, 3, rByte);
}
else{
rA = RNONE;
rB = RNONE;
}
//does fetched instruction require a constant word?
//bool need_valC;
bool needVC = needValC(f_icode);
unsigned int f_valC;
f_valC = getValC(f_pc, needRId, needVC);
/*
if(needVC){
unsigned char byte0 = getByte(f_pc+1, &memError);
unsigned char byte1 = getByte(f_pc+2, &memError);
unsigned char byte2 = getByte(f_pc+3, &memError);
unsigned char byte3 = getByte(f_pc+4, &memError);
f_valC = buildWord(byte0, byte1, byte2, byte3);
}
else
f_valC = 0;
*/
/*
if(instr_valid){
F.predPC = f_pc+1;
}
else{
F.predPC = f_pc+5;
}
*/
unsigned int f_valP;
f_valP = pcIncrement(f_pc, needVC, needRId);
F.predPC = predictPC(f_icode, f_valC, f_valP);
memError = true;
updateDregister(f_stat, f_icode, f_ifun, rA, rB, f_valC, f_valP);
}
