CSE 320 Summer 2019
Computer Project #6
Assignment Overview
This assignment develops familiarity with the instruction set architecture of the ARM microprocessor, as well as
the format of its machine language instructions.
It is worth 40 points (4% of course grade) and must be completed no later than 11:59 PM on Friday, 6/7.
Assignment Deliverables
The deliverables for this assignment are the following files:
proj06.makefile – the makefile which produces "proj06"
proj06.support.c – the source code for your support module
proj06.driver.c – the source code for your driver module
Be sure to use the specified file names and to submit them for grading via the CSE handin system before the
project deadline.
Assignment Specifications
An assembler is a program which converts assembly language source code statements into machine language
instructions; a disassembler is a program which converts machine language instructions into assembly language.
1. You will develop a support module which could be used by a disassembler for ARM machine language
instructions. The interface to the support module is the following C function:
void decode( unsigned int, char[] );
The first argument is the bit pattern for an ARM machine language instruction.
The second argument is the address of an array where function “decode” will store a null-terminated character
string representing the machine language instruction.
Function “decode” will accept a 32-bit unsigned integer value and attempt to disassemble it. If the bit pattern
corresponds to an ARM machine language instruction from the set defined below, function “decode” will produce
a human-readable representation of the instruction and store it in the array (the second argument). Otherwise, it
will produce an appropriate warning and store it in the array.
The support module will consist of function “decode” and any additional helper functions which you choose to
implement. The support module will not perform any input or output operations. For example, the functions in
the support module will not call function “scanf” or function “printf”.
2. You will develop a driver module to test your implementation of the support module. The driver module will
consist of function "main" and any additional helper functions which you choose to implement. All output will be
appropriately labeled.
Your driver module may not be written as an interactive program, where the user supplies input in response to
prompts. Instead, your test cases will be included in the source code as literal constants.
Assignment Notes
1. Your driver module and your support module must be in separate source code files.
2. Your source code must be translated by "gcc", which is a C compiler and accepts C source statements.
3. You must supply a "makefile" (named "proj06.makefile"), and that makefile must produce an executable
program named "proj06".
4. Your support module will recognize the ARM data processing instructions, which have the following format:
Bits 31:26 111000
Bit 25 I bit
Bits 24:21 opcode
Bit 20 S bit
Bits 19:16 Rn
Bits 15:12 Rd
Bits 7:0 immediate value (when I=1)
Bits 3:0 Rm (when I=0)
All other bits will be 0.
The sixteen operation codes are given in the following table:
Opcode Mnemonic Opcode Mnemonic
0000 and 1000 tst
0001 eor 1001 teq
0010 sub 1010 cmp
0011 rsb 1011 cmn
0100 add 1100 orr
0101 adc 1101 mov
0110 sbc 1110 bic
0111 rsc 1111 mvn
5. Your support module will produce a human-readable representation of a machine language instruction which is
in the same format as ARM assembly language instructions. Registers will appear as the character “r”, followed by
a decimal number between 0 and 15. Immediate constants will appear as the characters “#0x”, followed by a
hexadecimal number. For example:
Instruction Human-readable form
e086a007 add rl0, r6, r7
e096a007 adds rl0, r6, r7
e286a007 add rl0, r6, #0x7
e1520003 cmp r2, r3
e1a01003 mov r1, r3
6. Note that the functions in your support module cannot perform any input or output operations. All
communication between the driver module and the support module will be done via the two arguments to
function “decode”.