/*
* This procedure should decode the 32-bit instruction
* machineCode and instantiate it as an Instruction object
* The decoding process includes extracting values from the
* machineCode instruction for the opcode, func, rs, rt, rd,
* shamt, imm, and target fields, as well as assigning a format,
* token, and execution type (xtype)
*/
Instruction::Instruction(unsigned machineCode)
: raw (machineCode),
opcode (bitRange(31, 26)),
func (bitRange(5, 0)),
rs (bitRange(25, 21)),
rt (bitRange(20, 16)),
rd (bitRange(15, 11)),
shamt (bitRange(10, 6)),
imm (bitRange(15, 0)),
target (bitRange(25, 0))
{
switch (opcode) {
case 0:
format = R_TYPE;
switch(func) {
case 0:
token = SLL;
xtype = SHIFT;
break;
case 2:
token = SRL;
xtype = SHIFT;
break;
case 3:
token = SRA;
xtype = SHIFT;
break;
case 4:
token = SLLV;
xtype = SHIFT;
break;
case 6:
token = SRLV;
xtype = SHIFT;
break;
case 7:
token = SRAV;
xtype = SHIFT;
break;
case 8:
token = JR;
xtype = JUMP;
break;
case 9:
token = JALR;
xtype = JUMP;
break;
case 12:
token = SYSCALL;
xtype = OTHER;
break;
case 16:
token = MFHI;
xtype = ALU;
break;
case 17:
token = MTHI;
xtype = ALU;
break;
case 18:
token = MFLO;
xtype = ALU;
break;
case 19:
token = MTLO;
xtype = ALU;
break;
case 24:
token = MULT;
xtype = ALU;
break;
case 25:
token = MULTU;
xtype = ALU;
break;
case 26:
token = DIV;
xtype = ALU;
break;
case 27:
token = DIVU;
xtype = ALU;
break;
case 32:
token = ADD;
xtype = ALU;
break;
case 33:
token = ADDU;
xtype = ALU;
break;
case 34:
token = SUB;
xtype = ALU;
break;
case 35:
token = SUBU;
xtype = ALU;
break;
case 36:
token = AND;
xtype = ALU;
break;
case 37:
token = OR;
xtype = ALU;
break;
case 38:
token = XOR;
xtype = ALU;
break;
case 39:
token = NOR;
xtype = ALU;
break;
case 42:
token = SLT;
xtype = ALU;
break;
case 43:
token = SLTU;
xtype = ALU;
break;
default:
printf("unknown func: raw=%08x opcode=%u func=%u\n", raw, opcode, func);
assert(false && "unknown func");
}
break;
case 1:
format = I_TYPE;
xtype = BRANCH;
switch (rt) {
case 0:
token = BLTZ;
break;
case 1:
token = BGEZ;
break;
default:
printf("unknown opcode 1 subtype: raw=%08x rt=%u\n", raw, rt);
assert(false && "unknown opcode 1 subtype");
break;
}
break;
case 2:
token = J;
format = J_TYPE;
xtype = JUMP;
break;
case 3:
token = JAL;
format = J_TYPE;
xtype = JUMP;
break;
case 4:
token = BEQ;
format = I_TYPE;
xtype = BRANCH;
break;
case 5:
token = BNE;
format = I_TYPE;
xtype = BRANCH;
break;
case 6:
token = BLEZ;
format = I_TYPE;
xtype = BRANCH;
break;
case 7:
token = BGTZ;
format = I_TYPE;
xtype = BRANCH;
break;
case 8:
token = ADDI;
format = I_TYPE;
xtype = ALU;
break;
case 9:
token = ADDIU;
format = I_TYPE;
xtype = ALU;
break;
case 10:
token = SLTI;
format = I_TYPE;
xtype = ALU;
break;
case 11:
token = SLTIU;
format = I_TYPE;
xtype = ALU;
break;
case 12:
token = ANDI;
format = I_TYPE;
xtype = ALU;
break;
case 13:
token = ORI;
format = I_TYPE;
xtype = ALU;
break;
case 14:
token = XORI;
format = I_TYPE;
xtype = ALU;
break;
case 15:
token = LUI;
format = I_TYPE;
xtype = ALU;
break;
case 32:
token = LB;
format = I_TYPE;
xtype = LOAD;
break;
case 33:
token = LH;
format = I_TYPE;
xtype = LOAD;
break;
case 35:
token = LW;
format = I_TYPE;
xtype = LOAD;
break;
case 36:
token = LBU;
format = I_TYPE;
xtype = LOAD;
break;
case 37:
token = LHU;
format = I_TYPE;
xtype = LOAD;
break;
case 40:
token = SB;
format = I_TYPE;
xtype = STORE;
break;
case 41:
token = SH;
format = I_TYPE;
xtype = STORE;
break;
case 43:
token = SW;
format = I_TYPE;
xtype = STORE;
break;
default:
printf("unknown opcode: raw=%08x opcode=%u\n", raw, opcode);
assert(false && "unknown opcode");
break;
}
}
/*
* This procedure should decode the 32-bit instruction
* machineCode and instantiate it as an Instruction object
* The decoding process includes extracting values from the
* machineCode instruction for the opcode, func, rs, rt, rd,
* shamt, imm, and target fields, as well as assigning a format,
* token, and execution type (xtype)
*/
Instruction::Instruction(unsigned machineCode)
: raw (machineCode),
format (IFORMAT_NONE),
xtype (XTYPE_NONE),
token (ITOKEN_NONE),
opcode (bitRange(31, 26)),
func (bitRange(5, 0)),
rs (0),
rt (0),
rd (0),
shamt (0),
imm (0),
target (0)
{
switch (opcode) {
case 0:
format = R_TYPE;
switch(func) {
case 0:
token = SLL;
xtype = SHIFT;
break;
case 2:
token = SRL;
xtype = SHIFT;
break;
// Add remaining cases for func files
case 8:
token = JR;
xtype = JUMP;
break;
case 12:
token = SYSCALL;
xtype = OTHER;
break;
case 32:
token = ADD;
xtype = ALU;
break;
case 33:
token = ADDU;
xtype = ALU;
break;
case 34:
token = SUB;
xtype = ALU;
break;
case 35:
token = SUBU;
xtype = ALU;
break;
case 36:
token = AND;
xtype = ALU;
break;
case 37:
token = OR;
xtype = ALU;
break;
case 38:
token = XOR;
xtype = ALU;
break;
case 39:
token = NOR;
xtype = ALU;
break;
case 42:
token = SLT;
xtype = ALU;
break;
case 43:
token = SLTU;
xtype = ALU;
break;
default:
break;
}
break;
case 2:
token = J;
format = J_TYPE;
xtype = JUMP;
break;
case 3:
token = JAL;
format = J_TYPE;
xtype = JUMP;
break;
case 4:
token = BEQ;
format = I_TYPE;
xtype = BRANCH;
break;
case 5:
token = BNE;
format = I_TYPE;
xtype = BRANCH;
break;
case 8:
token = ADDI;
format = I_TYPE;
xtype = ALU;
break;
case 9:
token = ADDIU;
format = I_TYPE;
xtype = ALU;
break;
case 10:
token = SLTI;
format = I_TYPE;
xtype = ALU;
break;
case 11:
token = SLTIU;
format = I_TYPE;
xtype = ALU;
break;
case 12:
token = ANDI;
format = I_TYPE;
xtype = ALU;
break;
case 13:
token = ORI;
format = I_TYPE;
xtype = ALU;
break;
case 14:
token = XORI;
format = I_TYPE;
xtype = ALU;
break;
case 15:
token = LUI;
format = I_TYPE;
xtype = ALU;
break;
case 32:
token = LB;
format = I_TYPE;
xtype = LOAD;
break;
case 33:
token = LH;
format = I_TYPE;
xtype = LOAD;
break;
case 35:
token = LW;
format = I_TYPE;
xtype = LOAD;
break;
case 36:
token = LBU;
format = I_TYPE;
xtype = LOAD;
break;
case 37:
token = LHU;
format = I_TYPE;
xtype = LOAD;
break;
case 40:
token = SB;
format = I_TYPE;
xtype = STORE;
break;
case 41:
token = SH;
format = I_TYPE;
xtype = STORE;
break;
case 43:
token = SW;
format = I_TYPE;
xtype = STORE;
break;
// Add remaining cases for opcodes
default:
break;
}
}
