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CS 315-02 Lecture/Lab — Meeting Summary (Fall 2025)

  • Date: Sep 04, 2025
  • Time: 02:48 PM Pacific Time (US & Canada)
  • Meeting ID: 868 6589 0521
  • Instructor: Greg

Quick Recap

Greg led a comprehensive session on assembly programming fundamentals—functions, arrays, and control flow—emphasizing calling conventions and memory management. The session featured: - Practical demonstrations of array manipulation, loop structures, and conditional branching - Explanations of register usage, memory layout, and load/store operations - Guidance on debugging with GDB - Notes on GitHub Classroom access issues - An overview of upcoming lab assignments combining arrays and conditionals

Next Steps (Action Items)

  • Students: Complete the micro editor guide to learn the key bindings demonstrated.
  • Students: Implement assembly for Lab 3 based on the provided C code.
  • Students: Learn and apply function calling conventions in assembly for compatibility with C.
  • Students: Practice array operations in assembly using load/store instructions.

Summary of Topics

Assembly Programming Fundamentals Overview

  • Focus areas: functions, arrays, control structures.
  • Emphasis on following conventions to ensure compatibility with compiled C code.
  • Introduction to control instructions (e.g., return) and preview of memory instructions.
  • Goal: provide the core concepts needed to write basic assembly programs.

Assembly Code Testing Techniques

  • Structure of a C main program for testing assembly, including prototypes and function calls.
  • Efficient editing with the micro text editor (file and pane management).
  • Convention: embedding C function prototypes in assembly files for clarity.
  • Strategy: break down complex expressions into simpler assembly operations; manage return values.
  • Example transition: using arrays instead of individual arguments and how arrays are allocated in memory.

Memory and Registers in Computing

  • How processors move data: load from memory into registers for computation.
  • Load word (LW): transfers 32-bit values from memory to a register; analogous to pointer dereferencing in C.
  • Example described: implementing a C function that adds the first three elements of an int array, with a plan to show the assembly equivalent.

Assembly Language Array Summation

  • Loop structure for summing elements of an int array.
  • Steps: load elements, increment pointer, accumulate sum.
  • Initialization techniques: three ways to set a register to zero.
  • Core instructions: LW and ADD for repeated accumulation.

Keyboard Origins and Modern Usage (Contextual Note)

  • “Return” derives from typewriter carriage return; “Enter” indicates data submission on modern systems.
  • Apple uses Control (early control sequences) and Command (standardized shortcuts).
  • Observation: Linux cut/paste can be awkward; macOS shortcuts are more uniform.
  • Usability tip: remapping Caps Lock to Control can improve ergonomics.

Memory Layout and Pointer Representation

  • Pointers represented as hexadecimal values; focus on stack memory layout.
  • GDB demonstration: stepping through array arithmetic while observing register use.
  • For Lab 3: only read from arrays; future lessons will introduce storing/updating elements.

GitHub Classroom Access Issues

  • Reported issues affecting several students (including Noor and Leo).
  • Upcoming topics: stack and pointers next week, foundational for recursion.
  • GDB tip: use Control-L to refresh the interface when the screen becomes misaligned.

Assembly Language Control Flow Basics

  • Lab 2 and Lab 3 rules: use a and t registers; a0 used for return values.
  • Core concepts: labels, jumps, and conditional branches for control flow.
  • Importance: master these before tackling loops and if-else patterns.

C to Assembly Language Conversion

  • Translating C if-else logic into assembly by introducing labels and conditional jumps.
  • Technique: often reverse the branching logic relative to C for clarity.
  • Framing: treat assembly like a puzzle to manage increased complexity.
  • Example guided: read a command-line value; return 0 or 1 based on whether it’s greater than 0.

Assembly Language Programming Fundamentals

  • Implementing conditionals and loops via branches and jumps.
  • Debugger use to trace program execution and validate control flow.
  • Note: indentation and label names aid readability only; they do not affect execution.
  • Loops can be built solely with conditional branches and jump instructions.

C-Style Loops in Assembly Language

  • For-loop pattern: initialize, compare, branch, update, repeat.
  • Constructs used: labels, jumps, comparison branches.
  • Example: summing numbers from 0 to N-1.
  • Clarification: a single conditional jump suits do-while, not a loop that may skip the body entirely.

Assembly Language Debugging Tutorial

  • Walkthrough: program that sums numbers from 0 to n-1.
  • Focus areas: loop structure, conditionals, variable updates.
  • GDB usage: step through instructions, inspect registers and memory.
  • Closing: next lab combines loops, arrays, and conditionals; students should review the assembly guide.