The ori instruction stands for “or immediate”. It is used to perform a bitwise OR operation between a register and a 16-bit constant, with the result being stored in a register. Unlike li, move, and la, ori is not a pseudo-instruction.
Syntax
ori $t, $s, constant
Here, $t is the target register, $s is the source register, and constant is the 16-bit constant to be ORed with the contents of $s.
The ori instruction performs the following steps:
It takes the contents of register $s and the 16-bit constant.
It performs a bitwise OR operation between the two.
It stores the result into the target register $t.
Example:
lui $t1, 0x1234 # Load the constant value 0x1234 into the upper 16 bits of $t1 ori $t1, $t1, 0x5678 # Perform a bitwise OR operation between $t1 and 0x5678
lui $t1, 0x1234 loads the constant value 0x1234 into the upper 16 bits of the register $t1, resulting in 0x12340000 in $t1
ori $t1, $t1, 0x5678 performs a bitwise OR operation between the contents of $t1 (0x12340000) and 0x5678, resulting in 0x12345678 in $t1
Note
The ori instruction is often used in combination with the lui instruction to form larger constants or addresses. For example, to load a 32-bit constant into a register, you could use lui to load the upper 16 bits and ori to load the lower 16 bits. Similarly, to load the address of a label into a register, you could use lui to load the upper 16 bits of the
