Chapter IV: Macro Processors
Overview:
 To study the design and implementation of macro
processors.
 A macro represents a commonly used group of
statements in the source programming language.
 The macro processor replaces each macro instruction
with the corresponding group of source language
statements. (expanding)
4. 1
Macro Processors
Basic macro processor functions
 Macro definition
 Invocation
 Expansion (with substitution of parameters)
4. 2
Macro Processors
Basic macro processor functions
 Macro definition
 Invocation
 Expansion (with substitution of parameters)
4. 3
Macro Processors
Basic macro processor functions
 Macro definition
 Invocation
 Expansion (with substitution of parameters)
4. 4
Macro Processors
4. 5
Macro Processors
Use of macros in a SIC/XE program
4. 6
Macro Processors
Use of macros in a SIC/XE program (cont.)
4. 7
Macro Processors
Program from above with macros expanded
4. 8
Macro Processors
Program from above with macros expanded (cont.)
4. 9
Macro Processors
Discussions…
 Why does macro statement use JLT *-14?
 Allow label?
4.10
Macro Processors
Macro processor algorithm and data structures
 For one-pass macro processor, the definition of a
macro must appear in the source program before
any statements that invoke that macro.
 Three important tables are used for the macro
processor: NAMTAB、DEFTAB、and ARGTAB.
4.11
Macro Processors
Macro processor algorithm and data structures (cont.)
4.12
Macro Processors
Macro processor algorithm and data structures
4.13
Macro Processors
Macro processor algorithm and data structures (cont.)
4.14
Macro Processors
Macro processor algorithm and data structures (cont.)
4.15
Macro Processors
Machine-Independent Macro Processor Features
---- Concatenation of Macro Parameters
 This feature enable a program to generate a series
of variables named by XA1, XA2, XA3, …, etc.
and XB1, XB2, XB3, …, etc. as well.
 The body of the macro definition might contain a
statement like
LDA
X&ID1
 It has some problems!!
(solution: concatenation operator)
4.16
Macro Processors
Machine-Independent Macro Processor Features
---- Concatenation of Macro Parameters (cont.)
4.17
Macro Processors
Machine-Independent Macro Processor Features
---- Generation of unique labels
 In general, the body of a macro instruction that
contains labels is not possible.
 It will cause duplicate definition.
 Solution: use relative addressing (e.g., JEQ *03)
 Drawback: For short jump, it is acceptable.
For longer jump, it is not convenient, errorprone, and difficult to read .
4.18
Macro Processors
Machine-Independent Macro Processor Features
---- Generation of unique labels (cont.)
4.19
Macro Processors
Machine-Independent Macro Processor Features
---- Generation of unique labels (cont.)
4.20
Macro Processors
Machine-Independent Macro Processor Features
---- Conditional Macro Expansion
 For previous examples of macro instructions, these
statements could be varied by the substitution of
parameters, but the form of the statement, and the
order in which they appeared, were unchanged.
 Conditional macro expansion adds greatly to the
power and flexibility of a macro language.
4.21
Macro Processors
Machine-Independent Macro Processor Features
---- Conditional Macro Expansion (cont.)
4.22
Macro Processors
Machine-Independent Macro Processor Features
---- Conditional Macro Expansion (cont.)
Ps. &EORCK is a macro-time variable.
4.23
Macro Processors
Machine-Independent Macro Processor Features
---- Conditional Macro Expansion (cont.)
4.24
Macro Processors
Machine-Independent Macro Processor Features
---- Conditional Macro Expansion (cont.)
4.25
Macro Processors
Machine-Independent Macro Processor Features
---- Macro-time looping statements
4.26
Macro Processors
Machine-Independent Macro Processor Features
---- Macro-time looping statements (cont.)
4.27
Macro Processors
Machine-Independent Macro Processor Features
---- Keyword Macro Parameters
 Positional parameter vs. Keyword parameter
GENER , , DIRECT, , , , , , 3.
GENER TYPE=DIRECT, CHANNEL=3.
4.28
Macro Processors
Machine-Independent Macro Processor Features
---- Keyword Macro Parameters (cont.)
4.29
Macro Processors
Machine-Independent Macro Processor Features
---- Keyword Macro Parameters (cont.)
4.30
Macro Processors
Machine-Independent Macro Processor Features
---- Keyword Macro Parameters (cont.)
4.31
Macro Processors
Macro Processor Design Options
---- Recursive Macro Expansion
 The invocation of one macro, which is defined by
another macro instruction.
 Using a programming language that allows recursive
calls to write the macro processor.
4.32
Macro Processors
4.33
Macro Processors