1. Macros Covers chapter 8, pages 300 – 314

2. Run-time vs. Assemble-time Almost everything but the main body of an assembly-language program deals with assemble-time Header Equates Data Closing For the most part, the only run-time portion is the body

3. Run-time vs. Assemble-time (cont.) Programming the assembler Directives – instructions to the assembler on how or what to assemble Macros – programmer-defined directives

4. Macros Macros exist to avoid repetition (or avoid typing) increase clarity avoid function call overhead Macros work by substitution Types of macros Replacing Repeating

5. Replacing Macros Syntax: MACRO ENDM Example: MACRO Terminate movah, 04Ch moval, [exCode] int21h ENDM Terminate Example program term.asm

6. .lst File Created by the /l tasm command-line switch Contains everything but the kitchen sink: program code machine code expanded macros symbol table macro table group and segment table Extremely useful for debugging code with macros

7. Parameters Formal parameters only exist within the macro do not represent immediate values or offsets are text-replaced Example: MACRO Inc2 v1 incv1 ENDM Inc2 Example program inc2.asm

8. Parameters (cont.) Actual parameters are the text that is actually used when substituting the macro Example: Inc2ax The text “ax” is the actual parameter Example program shleft.asm

9. Parameter Modifiers Actual parameters <> - forces parameter to contain spaces % - forces evaluation first (use with “()”) ! – “escapes” other two Formal parameters & - recognize next word as a parameter Example program shleft2.asm Example program asciiz.asm

10. Repeating Macros IRP – Instruction RePeat Syntax: IRP, ENDM Repeats the instruction (in the source code itself) for every element Example programs save.asm and save2.asm

11. Local Labels Consider the following: MACROIncNumop, count pushcx movcx, count @@Back: incop loop@@Back popcx ENDMIncNum

12. Local Labels (cont.) The LOCAL directive solves the problem: MACROIncNumop, count LOCAL@@Back pushcx movcx, count @@Back: incop loop@@Back popcx ENDMIncNum