Project #7 Solution

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.
Assignment Deliverables
The deliverables for this assignment are the following files:
proj07.makefile – the makefile which produces "proj07" proj07.support.c – the source code for your support 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
The program will simulate the actions of the CPU during the fetch-execute cycle for the ARM microprocessor.

    1. The instructor-supplied driver module contains the definition of function "main" and some auxiliary functions. For each machine language instruction to be processed, it will simulate the steps of the fetch phase of the cycle and will then call function "execute" to simulate the steps of the execute phase.

    2. You will develop a support module which can be used to process a subset of the ARM machine language instructions. The interface to the support module is the following C function:

void execute();

Function "execute" will decode and process the instruction in the IR, then update the register file and the CPSR (when appropriate). It will recognize only the 16 data processing instructions as legal instructions.

    3. The driver module and your support module will communicate using the following global data objects: unsigned int IR, CPSR;

The driver module will place values into those two variables before calling function "execute"; function "execute" will use those values for its processing and will update variable "CPSR" before returning.

4. In the CPSR, bits 31:28 are the integer condition codes and bit 0 is the illegal instruction flag (1 means illegal).

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 "proj07.makefile"), and that makefile must produce an executable program named "proj07".

    4. Function "execute" will recognize the ARM data processing instructions, which have the following format:

Bits 31:26 Bit 25 Bits 24:21 Bit 20 Bits 19:16 Bits 15:12 Bits 7:0 Bits 3:0

111000

I bit
opcode
S bit
Rn
Rd

immediate value (when I=1)
Rm (when I=0)

All other bits will be 0 in a legal instruction.

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. 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 global variables.

    6. The file named "/user/cse320/Projects/project07.hardware.h" contains the following declarations (see the file for additional comments):

typedef unsigned
int signal4;

typedef unsigned
int signal32;

extern unsigned int IR, CPSR;

void read_reg_file

(



signal4,
/* RS1 selection signal */
signal4,
/* RS2 selection signal */
signal32*,
/* RS1 output port
*/
signal32*
/* RS2 output port
*/
);



void write_reg_file

(



signal4,
/* RD selection signal
*/
signal32
/* RD input port
*/
);