Arithmetic operations make up the majority of functions in the Assembly languages.
After all, the manipulation of binary numbers is how you execute any type of code, whether that be changing a character from lowercase to upper case or turning a pixel on a screen from red to blue.
One of the most important aspects of mathematical operations is how numbers are stored at the machine hardware level. Memory locations, such as registers, cache, or secondary storage, all have fixed binary lengths.
These fixed lengths mean that processors must have special registers to “catch” overflow from operations. Overflow operations can include handling extremely large numbers, marking when a carryover occurs in addition or storing both the quotient and remainder of division operations.
Most languages allow for at least two distinct types of each arithmetic operation. One type performs a calculation on two registers and the other performs an operation using one value from a register and another value that is directly added, known as an immediate or constant.
The addition calculation for example can be called using the
ADD opcode which then takes three registers as operands, two registers to add together and another to store the answer in.
The addition function also has an
ADDI command, which takes a register address and a constant to operate on and a register to store the answer in.
ADD function, the value in $5 is added to the value in $4 and stored in $6.
ADD $4, $5, $6
ADDI function, the constant 7 is added to the value in $4 and stored in $6
ADDI $4, $6, 7
Other common arithmetic operations include:
Create a new variable,
answer_1, and set it equal to the number of registers that are used in a typical
Create another variable,
answer_2, and set it equal to the value of the constant in this statement:
ADDI ($5), $9, 15