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Assembly Programming

This document provides an overview of jump statements in assembly programming, essential for creating flow control in your programs. It covers the simplest form of jump statement (jmp), equality comparisons with instructions such as CMP, and conditional jumps like JE and JNE. Additionally, it discusses various jump instructions based on operand comparisons, including greater than, less than, and equality checks. Through practical examples, it demonstrates how to manage user inputs, such as a PIN entry system, using loops and conditional statements in assembly language.

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Assembly Programming

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  1. Assembly Programming Notes for Practical 3 Munaf Sheikh http://www.cs.uwc.ac.za/~msheikh/COS365Assembler

  2. Jump statements • Simplest form of Jump statement • “jmp Lable” • Equivalent to GOTO • Simply says: Jump to Label

  3. Equality Comparison • CMP leftOp, rightOP • Compares the leftOperand to the rightOperand • Jumps based on Equality: • JE (jump if equal) • JNE (jump if not equal) • JCXZ (jump if CX = 0) • JECXZ (jump if ECX = 0)

  4. More Equality jumps • JG (jump if greater) • JNLE (jump if not less than or equal to) • JGE (jump if greater or equal) • JNL (jump if not le) • JL (jump if less) • Etc..: JNGE, JLE, JNG

  5. start TRUE FALSE expression Statement List 1 Statement list 2 end IF ELSE’s If (Expression) Statement List 1 Else Statement List 2

  6. IF ELSE’s Initial code here Cmp op1 op2 Je L1 If (OP1 == OP2){ X = 1; Y = 2; } Else { Z = 1; } L1: Mov X,1 Mov Y,2 Jmp L3 L2: Mov Z, 1 Jmp L3 L3:

  7. start Expression FALSE TRUE Statement List End While Loops While (Expression) Statement List

  8. Prac 3 • Write an Assembly Program that: • prompts the user for a System Administrator pin (PIN). • prompts the user for an Iteration Limit (LIMIT). • prints "---THE SYSTEM IS NOW RUNNING---" • Loop until counter = LIMIT • prompt user for pin • if pin == PIN, jump to CORRECTPIN handling code • else print error message and increment counter • jump back to beginning of loop. Save as access.asm

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