0 1 0 1 0 0 1 0 0 1 1 0 1 0 1 1 1 1 1 1 1 1 0 0 0 0
001101 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
ori $10 $9 a f f 0
operand dest immediate operand
reg. reg.
Here
again is the ori machine instruction:
3 4 0 8 0 f a 5 -- machine instruction in hex
001101 00000 01000 0000 1111 1010 0101 -- fields of the instructuion
opcode oper dest immediate operand -- meaning of the fields
-and reg.
reg.
ori $0 $8 0 f a 5
The layout of this machine instruction is different from the
addu instruction we looked at in chapter 10:
0 1 0 9 5 0 2 1 -- machine instruction in hex 000000 01000 01001 01010 00000 100001 -- fields of the instruction opcode oprnd oprnd dest ----- 2ndary -- meaning of the fields ALUop $8 $9 $10 addu
Both instructions are 32 bits wide (as are all MIPS32 instructions).
The first six bits are the opcode, which calls for an ALU operation.
The addu instruction further specifies the operation
in the last six bits, the secondary opcode.
The addu instruction does not have an immediate operand.
Do the fields of two different machine instructions necessarily have the same size and same meaning?