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Perry Kivolowitz
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README.md
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README.md
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@ -16,13 +16,15 @@ We drive home a very sharp point:
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</br>
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<h2>
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<a href="#section-1---bridging-from-c--c-to-assembly-language">
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Quick Link to Table of Contents
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</a>
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<a href="#table-of-contents">
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Quick Link to Table of Contents
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</a>
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</h2>
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</br>
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<br/>
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## For Whom Is This Book Intended?
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## Front Matter
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### For Whom Is This Book Intended?
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As mentioned, if you are already familiar with C (or languages descended
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from C such as C++), this book begins with what you already know.
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@ -31,11 +33,11 @@ Later chapters dive more deeply into the corners and recesses of the ARM
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V8 ISA and are suitable for those wishing to master the rich instruction
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set of the 64 bit ARM processors.
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## Can This Book Be Used In Courses Covering Assembly Language?
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### Can This Book Be Used In Courses Covering Assembly Language?
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Yes, absolutely.
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## Calling Convention Used In This Book
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### Calling Convention Used In This Book
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Assembly language programming is quite closely dependent upon the
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underlying hardware architecture. The host operating environment plays
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@ -87,7 +89,7 @@ explained in the chapter, that differ from system to system and
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architecture to architecture even for making the same system call. The
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CRT hides these differences.
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## A Lot of Names
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### A Lot of Names
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As commendable as the ARM designs are, ARM's naming conventions for
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their Intellectual Properties are horrid. In this book, AARCH64 and ARM
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@ -103,7 +105,7 @@ Within the text we will provide germane links as appropriate.
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[Here](<https://developer.arm.com/documentation/ddi0596/2021-12?lang=en>)
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is a link to "a" main instruction set page.
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## What you need to work with assembly language on Linux
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### What you need to work with assembly language on Linux
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Getting the tools for assembly language development is quite straight
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forward - perhaps you already have them. Using `apt` from the Linux
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@ -124,7 +126,7 @@ into a terminal and follow directions. Note that `gdb` is replaced by
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Then you'll need your favorite editor. We currently use `vi` for quick
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edits and Visual Studio Code for any heavy lifting.
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## How to build an assembly language
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### How to build an assembly language
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We use `gcc`, the C "compiler". `g++` could also be used. On the Mac,
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`clang` can also be used.
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@ -165,7 +167,7 @@ Suppose you've implemented `main()` in a C file (main.c) and want to
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make use of an assembly language file you have written (asm.S). It can
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be done in several ways.
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### All at once
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#### All at once
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```text
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gcc main.c asm.S
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@ -175,7 +177,7 @@ That's all you need for a minimal build. The resulting program will be
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written to `a.out`. All the intermediate files generated will be
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removed.
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### Modularly
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#### Modularly
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```text
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gcc -c main.c
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@ -201,7 +203,7 @@ Often, you will want to enable the debugger `gdb` or `lldb`. Do this:
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gcc -g main.S
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```
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### The C Pre-Processor
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#### The C Pre-Processor
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If you want `gcc` to run your code through the C pre-processor
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(for handing `#include` for example), name your assembly language
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@ -215,7 +217,7 @@ Will not go through the C pre-processor but
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will.
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### Programs called by the "Compiler"
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#### Programs called by the "Compiler"
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To drive home the point that the "compiler" is an umbrella, using gcc to
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"compile" a program causes the following to be called on Ubuntu running
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@ -262,6 +264,7 @@ knowledge - how cool is that!
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| 4b | [Load and Store](./section_1/regs/ldr.md) | [Link](./section_1/regs/ldr.pdf) |
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| 4c | [More About `ldr`](./section_1/regs/ldr2.md) | [Link](./section_1/regs/ldr2.pdf) |
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| 4d | [Register Sizes](./section_1/regs/widths.md) | [Link](./section_1/regs/widths.pdf) |
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| 4e | [Hexadecimal](./section_1/hex.md) | [Link](./section_1/hex.pdf) |
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| 5 | [`switch`](./section_1/jump_tables/README.md) | [Link](./section_1/jump_tables/README.pdf) |
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| 6 | Functions | |
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| 6a | [Calling and Returning](./section_1/funcs/README.md) | [Link](./section_1/funcs/README.pdf) |
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@ -306,17 +309,20 @@ What would a book about assembly language be without bit bashing?
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### Section 4 - More Stuff
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In this section, we present miscellaneous material.
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| Chapter | Markdown | PDF |
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| ------- | -------- | --- |
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| --- | [Determining string literal lengths for C functions](./more/strlen_for_c/README.md) | [Link](./more/strlen_for_c/README.pdf) |
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| --- | [Under the hood: System Calls](./more/system_calls/README.md) | [Link](./more/system_calls/README.pdf) |
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| --- | [Apple Silicon](./more/apple_silicon/README.md) | [Link](./more/apple_silicon/README.pdf) |
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| --- | [Apple / Linux Convergence](./macros) | [Link](./macros/README.pdf) |
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| --- | [Variadic Functions](./more/varargs/README.md) | [Link](./more/varargs/README.pdf) |
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| 1 | [Apple Silicon](./more/apple_silicon/README.md) | [Link](./more/apple_silicon/README.pdf) |
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| 2 | [Apple / Linux Convergence](./macros) | [Link](./macros/README.pdf) |
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| 3 | [Variadic Functions](./more/varargs/README.md) | [Link](./more/varargs/README.pdf) |
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| 4 | [Under the hood: System Calls](./more/system_calls/README.md) | [Link](./more/system_calls/README.pdf) |
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| 5 | [Determining string literal lengths for C functions](./more/strlen_for_c/README.md) | [Link](./more/strlen_for_c/README.pdf) |
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## Macro Suite
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As mentioned above, the macro suite [can be found here](./macros/).
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As indicated immediately above, the macro suite [can be found
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here](./macros/).
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## Projects
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@ -324,28 +330,28 @@ As mentioned above, the macro suite [can be found here](./macros/).
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challenge to your growing mastery. Here are very brief descriptions
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presented in alphabetical order.
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Perhaps before you tackle these, check out the fully described
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Perhaps before you tackle these, check out the fully described
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[FIZZBUZZ](./section_1/fizzbuzz/README.md) program first.
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Then try [this](./projects/first_project/README.md) as your very first
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* Then try [this](./projects/first_project/README.md) as your very first
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project. With some blank lines and comments it weighs in at 35 lines.
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The [DIRENT](./projects/DIRENT/README.md) project demonstrates how a
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* The [DIRENT](./projects/DIRENT/README.md) project demonstrates how a
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complex `struct` can be used in assembly language.
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The [PI](./projects/PI/README.md) project demonstrates floating point
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* The [PI](./projects/PI/README.md) project demonstrates floating point
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instructions. The program will "throw darts at a target," calculating
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an approximation of PI by tracking how many darts "hit the target"
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versus the total number of darts "thrown".
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The [SINE](./projects/SINE/README.md) project stresses floating point
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* The [SINE](./projects/SINE/README.md) project stresses floating point
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math and functions.
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The [SNOW](./projects/snow/README.md) project uses 1970's era tech to
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* The [SNOW](./projects/snow/README.md) project uses 1970's era tech to
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animate a simple particle system. This project demonstrates a reasonable
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design process of breaking down complex problems into simpler parts.
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The [WALKIES](./projects/walkies/README.md) presents a cute little
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* The [WALKIES](./projects/walkies/README.md) presents a cute little
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animation demonstrating looping with some pointer dereferencing.
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## About The Author
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@ -360,18 +366,18 @@ LLC](https://en.wikipedia.org/wiki/SilhouetteFX). SilhouetteFX is used
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in almost every significant motion picture for rotoscoping, paint,
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tracking, 2D to 3D reconstruction, compositing and more.
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In 1996 Perry received an [Academy Award for Scientific and
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Technical Achievement](https://en.wikipedia.org/wiki/Academy_Award_for_Technical_Achievement)
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for his invention of Shape Driven Warping and
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Morphing. This is the technique responsible for many of the
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famous effects in Forrest Gump, Titanic and Stargate.
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In 1996 Perry received an [Academy Award for Scientific and Technical
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Achievement](https://en.wikipedia.org/wiki/Academy_Award_for_Technical_Achievement)
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for his invention of Shape Driven Warping and Morphing. This is the
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technique responsible for many of the famous effects in Forrest Gump,
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Titanic and Stargate.
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Twenty twenty three marks Perry's 19th year teaching Computer Science at
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the college level, ten years at the UW Madison and now 8+ at Carthage
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College.
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Assembly language is a passion for Perry having worked in the following
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ISAs:
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ISAs (in chronological order):
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* Univac 1100
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@ -389,14 +395,17 @@ This work is dedicated to my wife Sara and sons Ian and Evan.
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Perry has created a library of about 200 programming projects suitable
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for CS 1, CS 2, Data Structures, Networking, Operating Systems and
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Computer Organization classes. If a publisher of CS text books would be
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interested in purchasing the library, please reach out.
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Computer Organization classes. If a publisher of CS text books (or other
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CS related content) would be interested in purchasing the library,
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please reach out.
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Also, check out [Get Off My
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L@wn](https://www.amazon.com/Get-Off-My-Zombie-Novel-ebook/dp/B00DQ26J8G),
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a Zombie novel for coders. You read that right... elite programmer Doug
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Handsman retires to his wife Ruth Ann's native northern Wisconsin. And
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then, well, the apocalypse happens. Bummer.
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a Zombie novel for coders.
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You read that right... elite programmer Doug Handsman retires to his
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wife Ruth Ann's native northern Wisconsin. And then, well, the
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apocalypse happens. Bummer.
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Rated 4.3 out of 5 with more than 70 reviews, it's a fun read and costs
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next to nothing.
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|
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# Section 1 / Hexadecimal
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Hex is only lightly covered here because there is a very good chance you
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are already familiar with the concept.
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The TL;DR is: Hex is base sixteen. Hex is useful because being base 16,
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each hex digit represents 4 bits and just two hex digits completely
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indicates the 8 bits in a byte. Hex digits run from 0 through 9 and then
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A through F. Example: decimal 255 is hex FF.
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## Numbers in Base 10
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You already know that each digit in a base 10 number is added to a power
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of 10. The first digit is added to 10 to the 0. The second digit is
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added to 10 to the 1 and so on.
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## Numbers in Base 2
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### Integers
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Binary is the same thing except with powers of 2.
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The first (least significant) digit is added to 2 to the 0. The second
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is added to 2 to the 1 and so on.
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### Floats
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Floats are more complicated but in rough terms the digits are raised to
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negative powers of 2. See [Section 2](../section_2/float/) for more
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detailed information.
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## Number in Base 16 - Hexadecimal
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Hex numbers work the same way as binary and decimal except there are
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more than 10 values for each digit. We draft the letter A through F to
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mean the values 10 through 15.
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Hex is a handy way of describing binary numbers with much less effort.
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## Octal - Numbers in Base 8
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We don't speak of such things.
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More seriously, base 8, or octal, is used far less than hex (permission
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bits in Linux is one place where it is used) in CS because it doesn't
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naturally encode into a single byte. Two hex digits perfectly since in a
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byte but two octal digits is 6 bits... too small and three octal digits
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is 9 bits... too big. Goldilocks does not approve.
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## Printing Hex
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With `printf()` use `%x`.
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With `iostream` use the modifier `hex` but note this is sticky. It will
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remain active until switched back to `dec`.
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## The REAL Reason We Love Hex
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You can spell stuff with hex.
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| Hex Value | Notes |
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| --------- | ----- |
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| DEADBEEF | Found frequently in MC68K code especially Amiga |
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| 8BADFOOD | Found for similar reasons but on Apple products |
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| DEADDEAD | Associated with the Blue Screen of Death |
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| F003BA11 | Used by undergraduates everywhere |
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| COEDBABE | Used by misogynists everywhere |
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| B16B00B5 | Used by misogynists at Microsoft |
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section_1/hex.pdf
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