Homework 7 Information, ECS50 Spring 1998

Homework due by Midnight Wednesday, June 3rd.

Assignment:

Write a subroutine capable of calculating the sum or difference of two long integer arrays. The results should be stored in a third array. A different subroutine should print out the result array. (For those of you that care, this is what Vector Processors like the CRAY do for a living.)

The requirements are:

The program should be written in MIPS assembly language and run on SPIM (XSPIM)
Parameters are passed using the regular MIPS convention (first 4 in regs, rest on stack)
The stack grows down in memory (push operations decrease the value of the stack pointer), and the stack pointer points to the next available slot (not the top element).
The subroutine expects 6 parameters (in this order):
a mode specifying whether to add or subtract
(0=add arrayA+arrayB, 1=subtract arrayA - arrayB)
the number of elements in arrayA,
the number of elements in arrayB,
the address of the first array (arrayA),
the address of the second array (arrayB),
the address of the third array (the result array, arrayR),
Your subroutine must not use any global variables.
The elements of arrayR contain the result of the specified operation on arrayA and arrayB.

Assumptions

Each array will not have more than 100 elements
You should be able to print both positive and negative numbers
Use the system calls to accomplish your printing

Extra Credit

Allow the data arrays to be entered from the keyboard (this isn't worth much!)

Examples

If	arrayA = 1,34,5 
and	arrayB = 2,0 
then	arrayR = 3,34,5 (arrayA + arrayB)