Professor Shai Simonson - CS304 - Computer Architecture



Assignment 5

Assembly Language Using MIPS
Translation and Assemblers

 

Due Monday, November 19.  (40 points)

0.  Type in the following lines to SPIM, and write down the translated MIPS instructions.

label:
        lw $7, label
        la  $8, label

        a.  Explain in your own words why and how the translation works. 
        b.  Write down the Hex representation for each instruction.  Explain how and why they are what they are.

1.  Hand assemble the folowing lines assuming instructions start at 0x0000 4400.
    add $3, $6, $19
    sb$3, 0($5)
    lw $8, 4($5)

2.  Hand assemble the folowing lines assuming instructions start at 0x0008 8800.

        and $5, $6, $18
        beq $5, $0, br1
        lui $20, 0x66aa
br1:   lb $9, -8($20)

3.  Reverse engineer these hex values into MIPS instructions.  Make up label names if needed.  Assume code starts at 0x0040 0000.
            Address             Contents
        0x0040 0000   0x8161 0000
        0x0040 0004   0x0068 a020
        0x0040 0008   0x0083 a004
        0x0040 000c   0x0681 fffd



Last Program (You can write this program in C++ or Java if you prefer) - A One Operand Assembler

The goal of this assignment is to write an assembler for the one operand, two address mode assembly language described below. You do not need to check for syntax errors.  You do need to generate the machine code.

The language has 8 instructions: Load, Store, Add, Sub, Bra, Bgtr, Bzr, End. Every instruction has at most one operand which must be a PC-relative address, or an immediate value. Immediate values are base 10 integer numbers preceeded by a #, and PC-relative addresses are written as labels. Every instruction is encoded in 16 bits. The first 3 bits of the instruction are for the opcode, the next bit indicates which of the 2 address modes to use (0 for PC-relative and 1 for immediate), and the last 12 bits hold either a two's complement offset for the PC-relative address (i.e.  the difference in bytes between that line and the label), or a two's complement immediate value. Labels must be 3 letters followed by a colon. If a label has no instruction following it, then it is assumed to be an empty 16 bits of memory. You may assume that every machine program will be loaded starting at memory location zero.  Note that End is encoded by 111000000000000.

You should read in the assembly program line by line until it sees End.  Then you should print out the machine language version.

Examples:

Here are two examples assuming you number the instructions in order from 000 through 111, and 0 indicates PC-relative while 1 indicates immediate address mode:

abc:                            xyz:
    Load #23                lop:  Add #-1
    Store abc                       Store xyz
    End                                Bzr  fin
                                          Bra  lop
                                    fin:  End

000 1 000000010111        010 1 111111111111
001 0 111111111100        001 0 111111111100
111 0 000000000000        110 0 000000000100
                                          100 0 111111111010
                                          111 0 000000000000
 

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shai@stonehill.edu

http://www.stonehill.edu/compsci/shai.htm