Michael Abrash’s Graphics Programming Black Book

1264 Pages·2001·132.104 MB·English

by  Michael Abrash

What’s on the CD-ROM
The companion CD-ROM includes all of the source code
published as numbered listings in the text of the book,
plus compiled executables of many of the demos. In ad-
dition, you’ll find the following extras on the CD:
The classic Zen Timer code profiling tool, in both executable and source
code format.
a\
4 Exclusive! The text of Michael’s long out of print 1989 cult classic Zen of
@
AsS6T373ibLlya nguage, plus scans of all 1 OOt technical figures.
ant essays from Michael’s ongoing work in game develop-
g for the first time in book form.
:nts, descriptions, copyrights, installation, limita-
‘n.
Hardware Platform: An Intel PC.
Note that some code is processor-specific.
To run all code you must have at least a
Pentium processor.
Wimiws 95 or NT. .

Black Book
Abrash
Michael
Albany, NY Belmont, CA Bonn Boston Clnclnnatl Detrolt Johannesburg London
Madrld Melbourne Mexlco C I N~ew York Paris Slngapore Tokyo Toronto Washlngton
Publisher Keith Weiskamp
Project Editor Denise Constantine
Production Proiect Coordinator Kim Eoff
Compositor Rob Mauhar
Cover Artist and Cover Design Anthony Stock
Proofreaders JefKellum and Meredith Brittain
Indexer Caroline Parks
CD-ROM Development Robert Clarfield
Michael Abrashs Graphics Programming Black Book, Special Edition
1-57610-174-6
Copyright 0 1997 by The Coriolis Group, Inc.
All rights reserved. This book may not be duplicated in any way without the express written
consent of the publisher, excepti n the form of brief excerpts or quotations fort he purposes of
review. The information contained herein is ftohre personal use of the reader and may not be
incorporated in any commercial programs, other books, databases, or any kind of software
without written consent of the publisher. Making copies of this book or any portion for any
purpose other than your own is a violation of United States copyright laws.
Limits of Liability and Disclaimer of Warranty
The author and publisher of this book have used their best effortsin preparing the book and
the programs contained in it. These efforts include the development, research, and testing of
the theories and programs to determine their effectiveness. Thaeu thor and publisher maken o
warranty of any kind, expressed or implied, with regatrod these programs or the documenta-
tion contained in this book.
The author and publisher shall notb e liable in the event of incidental or consequential dam-
ages in connection with, or arising out tohfe, furnishing, performance, our se of the programs,
associated instructions,a nd/or claims of productivity gains.
Tiademarks
Trademarked names appear throughout this book. Rather than list the names and entities that
own the trademarks or inserat trademark symbol withe ach mention of the trademarked name,
the publisher states thati t is using the names for editorialp urposes only and to the benefit of
the trademark owner, with no intention of infringing upon that trademark.
The Coriolis Group, Inc.
An International Thomson Publishing Company
14455 N. Hayden Road, Suite 220
Scottsdale, Arizona 85260
602/483-0192
FAX [phone]
http://www.coriolis.com
Printed in the United States of America
109876543
Acknowledgments
Because this bookw as written over many yearsi, n many different settings, an un-
usually large number of people have played a part in making this book possible.
First and foremost, thanks (yet again) to Jeff Duntemann for getting this book
started, doing thed irty work, and keeping things on track and everyone’s spirits
up. Thanks to Dan Illowsky for not only contributing ideas and encouragement,
but also getting me started writing articles long ago, when I lacked the confidence
to do it on my own-and for teaching me how to handle the business end of
things. Thanks to Will Fastie for giving me my first crack at writing for a large
audience in the long-gone but still-missed PC Tech Journal, and for showing me
how much fun it could be in his even longer-vanished but genuinely terrific col-
umn in Creative Computing (the most enjoyable single columnI have ever read in a
computer magazine; I used to haunt the mailbox around the beginning of the
month justt o see whatW ill had to say). Thanks to Robert Keller, Erin O’Connor,
Liz Oakley, Steve Bakaern, d the rest of the cast oft housands that made PJa uniquely
fun magazine-especiallyE rin, who did more thana nyone tot each me the proper
use of English language. (To this day, Erin will still patiently explain to me when
one should use “that” andw hen one should use “which”e ven though eight years
of instruction on this and related topics have left no discernible imprint on my
brain.) Thanks toJ on Erickson, Tami Zemel, Monica Berga,n d ther est of the DDJ
crew for excellent, professional editing, and forjusbt eing great people. Thanks to
the Coriolis gangf or their tireless hard work: JefDf untemann andK eith Weiskamp
on the editorial and publishing side, and Brad Grannis, Rob Mauhar, and Kim
Eoffwho handled art,d esign, and layout. Thanks to JiMm ischel who did a terrific
job testing code for the book and putting thec ode disk together. Thanks to Jack
Tseng, for teaching me a lot about graphics hardware, and even more about how
much difference hard work can make. Thanks J tooh n Cockerham, David Stafford,
Terje Mathisen,t he BitMan, Chris Hecker, Jim Mackraz, MeLlvainft te, JohnN avas,
Phil Coleman, Anton TruenfeJlosh, n Carmack,J ohn Miles,J ohn Bridges, Jim Kent,
Hal Hardenberg, Dave Miller, Steve Levy, Jack DaviDs, uane Strong, Daev Rohr, Bill
Weber, Dan Gochnauer, Patrick Milligan, Tom Wilson, the people in the ibm.pc/
fast.code topic on Bix, and all the rest of you who haveb een so generous with your
ideas and suggestions. I’ve done my best to acknowledge contributors by name in
this book, but if yourn ame is omitted, my apologies, and consider yourself thanked;
this bookc ould not have happened without you.A nd, of course, thanks to Shaya nd
Emily for their generous patience with my passion for writing and computers.
And, finally, thanks to the readers of my articles and to you, the reader of this
book. You are, after all, the ultimate reason why I write, and I hope you learn as
much and have as much fun reading this book as I did writing it!
Michael Abrash ([email protected])
Bellevue, Washington, 1997
To Shay
. C o n t e n t s
Foreword xxxi
Introduction xxxiii
Part I 1
Chapter 1 The Best Optimizer Is between
YouEr ars 3
The Human Element of Code Optimization 5
Understanding High Performance 6
When Fast Isn't Fast 6
Rules for Building High-Performance Code 7
Know Where You 're Going 8
Make a Big Map 8
Make Lots of Little Maps 8
Know the Ta'tory 12
Know When It Matters 13
AlwaysC onsidert he Alternatives 14
Know How to Turn Ont he Juice 16
Where We've Been, What We've Seen 19
WhereW e'reG oing 19
'
Chapter 2 A World Apart 21
The Unique Nature of Assembly
Language Optimization 23
Instructions: The Individual versus
the Collective 23
Assembly Is Fundamentally Different 25
Transfwmation Inefficiencies 25
Self-Rliance 27
vi i
Knowledge 27
The FlexibleM ind 28
Where to Begm ? 30
Chapter 3 Assume Nothing 31
Understanding and Using the Zen Timer 33
The Costs of Ignorance 34
The Zen Timer 35
The Zen Timer Is a Means, Not an End 42
Starting the Zen Timer 43
Time and the PC 43
Stopping the Zen Timer 46
ReportingT iming Results4 7
Notes on the Zen Timer 48
A Sample Use of the Zen Timer 49
The Long-Period Zen Timer 53
Stoppingt he Clock 54
Example Use of the Long-Period Zen Timer 66
Using the Zen Timer from C 69
Watch Out for Optimizing Assemblers! 71
Further Reading 72
Armed with the Zen Timq Onward and Upward 72
Chapter 4 In theL air of theC ycle-Eaters 75
How the PC Hardware Devours
CodeP erformance 77
Cycle-Eaters 78
The Nature of Cycle-Eaters 78
The 8088’sA ncestral Cycle-Eaters 79
The 8-Bit Bus Cycle-Eater 79
The Impact of the 8-Bit Bus Cycle-Eater 82
What to Do about the 8-Bit Bus Cycle-Eater? 83
The Prefetch Queue Cycle-Eater 86
Official Execution Times Are Only Part of the Story 87
There Is No Such Beast as a True Instruction Execution Time 88
Approximating OverallE xecutionT imes 93
What to Do abotuhP t er efetcQh u euC ey cle-Eater? 93
Holding Upt he 8088 94
Contents
Dynamic RAM Refresh: The Invisible Hand 95
How DRAM Refresh Works in the PC 95
The Impact of DRAM Refresh 97
What to Do About the DRAM Refresh Cycle-Eater? 98
Wait States 99
The Display Adapter Cycle-Eater 101
The Impact of the DisplayA dapter Cycle-Eater 104
What to Do about the Display Adapter Cycle-Eater? 107
Cycle-Eaters: A Summary 108
What Does It All Mean? 108
Chapter 5 Crossing the Border 1 1 1
Searching Files with Restartable Blocks 113
Searchingf or Text 114
Avoiding the String Trap 115
Brute-Force Techniques 115
Using memchr() 116
Making a Search Restartable 11 7
Interpreting Where the Cycles Go 121
Knowing When Assembly Is Pointless 122
Always Look Where Execution Is Going 123
Chapter 6 LookingP asFt aceV alue 125
How Machine Instructions May Do More Than
You Think 127
Memory Addressing and Arithmetic 128
Math via Memory Addressing 130
The Wonders of LEA on the 386 131
Multiplication with LEA Using Non-Powers
ofTwo 132
Chapter 7 Local Optimization 135
Optimizing Halfway between Algorithms
and Cycle Counting 137
When LOOP Is a Bad Idea 138
The Lessons of LOOP andJ CXZ 139
Avoiding LOOPS of Any Stripe 140