ARM Assembly

Course Assignments for CS 2400 and 3750
Spring 2015 / Fall 2016
Dr. Weiying Zhu
Metropolitan State University of Denver

Configuration and Execution

1. These ARM programs are configured to run with the Keil µVision v5 IDE. Before you begin, make sure that this application is properly installed and configured for your machine. [Note: you may wish to create a dedicated project directory before continuing.]

2. Within µVision, create a new project.

   1. Begin by selecting Project -> New µVision project... from the menu bar.
   2. Now navigate to the desired directory, select a name for your project, and click OK.
   3. In the Select Device for Target... window, expand ARM -> ARM Cortex M3 and select ARMCM3. Click OK.
   4. In the Manage Run-Time Environment... window, select CMSIS -> Core and Device -> Startup. Click OK.

3. Now that you have a new project created, let's finish configuring it by adding the appropriate source files and enabling the simulator.

   1. Within the Project window, navigate to Project: [project name] -> Target 1. Right click on Target 1 and select Options for Target `Target 1`.... Within this new dialogue, click the Debug tab and select Use Emulator. Click OK.
   2. Within the Project window again, navigate to Project: [project name] -> Target 1 -> Source Group 1. This is where you will add all relevant source files. To add a .s file, right click on Source Group 1 and select Add Existing Files to Group `Source Group 1`... .

4. With the source code added and the emulator configured, the project is ready to be built and tested.

   1. Select Project -> Build Project from the menu bar. Any errors or warnings will appear in the Build Output window. [Note: if you wish to test the application with different inputs, make sure the appropriate changes are made to the source files before building the project.]

   2. With the project built, you can enter the debug environment by selecting Debug -> Start/Stop Debug Sessions... from the menu bar.

   3. You may execute the application within the debug environment by selecting Run, or partially execute the application by selecting Step or Step Over.

   4. Once the application has finished running, you can interact with the result by using the Command window to query for specific exported variables.

      • Some applications will export memory values instead of a literal output. For these applications, you will need to enter the memory value provided into the Memory 1 window and configure the window to view the output data in the correct format. Notes for configuring the memory window can be found with each application below where applicable.

5. Now that you have run one application successfully, you can alter the source code used for the project by replacing the .s file in the Project: [project name] -> Target 1 -> Source Group 1 directory. Alternatively, you can create an entire new project (optionally with it's own new directory) and follow steps 1-4 again. Both of these options allow for testing new or altered applications.

Assignments

01 Hexadecimal Subtraction

This program converts two hexadecimal numbers into their appropriate two's complement and then subtracts the first operand from the second operand, storing the difference of "B-A" in memory.

Input

A: a hexadecimal value stored digit-by-digit. The default value is A05E65.
B: a hexadecimal value stored digit-by-digit. The default value is FA248B6E.

Output

Result: stores the literal value of the difference "B-A". The expected result given default inputs is F9842D09.

02 String Combination

This program takes two strings and combines them a character at a time, storing the interlaced string in memory.

Input

StrOne: the first null-terminated string to be combined. The default value is Hello World.
StrTwo: the second null-terminated string to be combined. The default value is To be or not to be.

Output

ADDR_MixStr: stores the memory address of the combined string. To view the string, enter this memory address into the Memory 1 Window, then right click anywhere in the memory display and select ASCII. The expected result given default inputs is HTeol lboe Woorr nlodt to be.

03 Hexadecimal to Decimal Conversion

This program takes a string representing a hexadecimal value in memory and converts it into a new string representing the equivalent decimal value with a unary negation if the value is negative.

Input

HexStr: the string representing a hexadecimal value. The default value is 3F0D5A.

Output

ADDR_DecStr: stores the memory address of the resultant decimal value string. To view the string, enter this memory address into the Memory 1 Window, then right click anywhere in the memory display and select ASCII. The expected result given the default input is 4132186.

04 Hamming Error Correction

This program takes a string containing a binary hamming code and recovers the source word, correcting any errors that can be identified.

Input

Code: the string containing the hamming code encrypted message, potentially with errors. The default value is 111111000001101.

Output

ADDR_Source: stores the memory address of the string containing the source word. To view the string, enter this memory address into the Memory 1 Window, then right click anywhere in the memory display and select ASCII. The expected result given the default input is 11101001101.

05 Valid Integer Accumulator

This program processes an array of signed, 32-bit integers and determines which values are within the range of [-100, 100]. The program produces as output the total number of values within the given range and the sum of all of those valid ints added together.

Input

IntArray: a contiguous array of up to 10 32-bit, signed integers. The default value in decimal is: [50, -125, 465, 232, 101, 145, 54, 25, -20].

Output

ADDR_Counter: stores the memory address of the number of integers within the valid interval. To view the integer, enter this memory address into the Memory 1 Window, then right click anywhere in the memory display and select Signed -> Int. Make sure the Decimal option is selected. The expected result given the default input in decimal is 5.
ADDR_Sum: stores the memory address of the total sum of all valid integers. To view the integer, enter this memory address into the Memory 1 Window, then right click anywhere in the memory display and select Signed -> Int. Make sure the Decimal option is selected. The expected result given the default input in decimal is 109.

06 TEA Decryption

This program implements the decryption half of the Tiny Encryption Algorithm (TEA), taking as input two encrypted message values and producing the original source words.

Input

LTwo: the "left-side" encrypted message stored in hexadecimal. The default value is B72599B2.
RTwo: the "right-side" encrypted message stored in hexadecimal. The default value is CF8E5A4C.

Output

LZero: the literal hexadecimal representation of the decrypted "left-side" source word. The expected result given the default input is A0000006.
RZero: the literal hexadecimal representation of the decrypted "right-side" source word. The expected result given the default input is 8000006B.

07 TEA Encryption

This program implements the encryption half of the Tiny Encryption Algorithm (TEA), taking as input two source words and producing the two-part encrypted message.

Input

LZero: the "left-side" unencrypted source word stored in hexadecimal. The default value is A0000006.
RZero: the "right-side" encrypted message stored in hexadecimal. The default value is 8000006B.

Output

LTwo: the literal hexadecimal representation of the encrypted "left-side" coded message. The expected result given the default input is B72599B2.
RTwo: the literal hexadecimal representation of the encrypted "right-side" coded message. The expected result given the default input is CF8E5A4C.