GUIDE TO COMPILING AND EXECUTING CODE

To run and compile assembly programs, ensure you have a suitable environment set up (e.g., NASM for x86 architecture). Follow these instructions for each task:

1. Compile the Assembly Code

   • For 64-bit systems:

     nasm -f elf64 <filename>.asm -o <filename>.o  

   • For 32-bit systems:

     nasm -f elf32 <filename>.asm -o <filename>.o  

2. Link the Compiled Object File

   ld <filename>.o -o <filename>  

3. Execute the Program

   ./<filename>  

Replace <filename> with the actual name of the task file (e.g., task1, task2, etc.).

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Task 1: Conditional Logic and Program Flow

Summary

This program determines whether a number entered by the user is "POSITIVE," "NEGATIVE," or "ZERO." It highlights the use of both conditional and unconditional jumps to control program execution.

Key Challenges

• Using Jump Instructions: Selecting between unconditional (jmp) and conditional jumps (je, jl, etc.) was crucial for accurate flow control.
• Branching Decisions: The program required careful planning to handle the three scenarios without compromising stability.

Takeaways

• Conditional jumps effectively simplify decision-making by leveraging comparisons for branching.
• Structuring the program into distinct sections improves readability and debugging efficiency.

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Task 2: Reversing Arrays with Loops

Summary

This program accepts an array of integers, reverses its order in memory, and displays the reversed result. The reversal process is performed using a loop and avoids allocating extra memory.

Key Challenges

• In-Place Reversal: Reorganizing elements within the same memory space required precise memory addressing.
• Boundary Checks: It was essential to iterate only halfway through the array to avoid errors like segmentation faults.
• Index Handling: Managing pointers for the array's start and end required close attention to avoid overlapping.

Takeaways

• Register-based pointer arithmetic improves the program’s performance by reducing memory access.
• Halving the number of iterations ensures the reversal process is efficient and avoids unnecessary computations.

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Task 3: Factorial Calculation with Modular Subroutines

Summary

This task involves computing the factorial of a user-supplied integer using a dedicated subroutine. The subroutine uses stack operations to preserve registers and applies a loop to perform repeated multiplications.

Key Challenges

• Register Preservation: Using the stack to save and restore register values was crucial to maintaining program stability.
• Input Conversion: Handling and validating ASCII input for conversion to an integer was necessary to prevent errors.
• Handling Large Values: Factorial calculations produce large results, so input values near the upper limit required testing to avoid overflow.

Takeaways

• Subroutines improve code modularity and reusability by isolating functionality.
• Proper stack management prevents interference with registers used in other parts of the program.

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Task 4: Simulating Sensor-Control Systems

Summary

This program mimics a water level monitoring system. Depending on the simulated sensor’s input value, the program performs the following actions:

1. Activates a "motor" when water is below the desired level.
2. Stops the motor when the water level is optimal.
3. Sounds an "alarm" when the water level exceeds the safe threshold.

Key Challenges

• Port Simulation: Representing input/output ports using memory locations required an innovative approach.
• Logic Design: Implementing efficient branching mechanisms to handle low, moderate, and high water levels without ambiguity.
• Memory Mapping: Correctly manipulating specific memory addresses to simulate sensor and motor interactions.

Takeaways

• Simulating hardware behavior through code provides a practical understanding of port-based systems without relying on actual hardware.
• Using clear logic and modular programming makes it easier to debug and expand the system’s functionality.