Inlining Assembly Language with GCC

Noteworthy without this article is Lockless (http://locklessinc.com/) for the great super-technical write-ups that they do.

Inlining assembly language using the GNU toolset has always escaped me (until now). It’s not so much that I didn’t know how to do it, I just felt it much more comfortable to write my assembly in a separately linked object. This article has put my mind, stomach and C blending assembly fingers at ease.

http://locklessinc.com/articles/gcc_asm/

Hello, 64bit Assembly!

So, I’m a tragic for assembly language. I’ve finally gotten around to sharpening up my skills to attack Linux with some assembly language and why not upgrade the skills into the 64bit world at the same time.

“Hello world” follows:

section .data
	hello:      db 'Hello world!',10    ; text plus a linefeed char
	helloLen:   equ $-hello             ; length of the string

section .text
	global _start
	
_start:
	mov   rax, 4            ; system call for "write" (sys_write)
	mov   rbx, 1            ; file descriptor (stdout = 1)
	mov   rcx, hello        ; offset to write
	mov   rdx, helloLen     ; number of bytes to write
	int   0x80              ; syscall
	
	mov   rax, 1            ; system call for exit (sys_exit)
	mov   rbx, 0            ; error code (no error = 0)
	int   0x80              ; syscall

Build at the command line with nasm:

nasm -f elf64 hello.asm
ld -s -o hello hello.o

Some further reading:

• http://docs.cs.up.ac.za/programming/asm/derick_tut/
• http://software.intel.com/en-us/articles/introduction-to-x64-assembly/

Core *nix Cheatsheets

Here’s a bookmark set (3 links) that have all got me out of trouble from time to time. If times and spaces were a little different around home here, I’d probably have these printed out and pinned to the wall.

• GNU Coreutils Cheat Sheet http://www.catonmat.net/download/gnu-coreutils-cheat-sheet.pdf

• Util-Linux Cheat Sheet http://www.catonmat.net/download/util-linux-cheat-sheet.pdf

• Bash Redirections Cheat Sheet http://www.catonmat.net/download/bash-redirections-cheat-sheet.pdf

Art for Programmers

Yet another productivity killer for any non-creative programmer trying to make a game is art.

So, the next time this is a problem - I’ll be going here: http://letsmakegames.org/resources/art-assets-for-game-developers/

Just came across this icon set as well: http://adamwhitcroft.com/batch/

UniVerse development cheatsheet

A cheatsheet of UniVerse commands

Command Prompt

Command Stack

All of the items with an “n” in their execution can either be removed (to operate on the most recent item) or replaced with a number indicating the item in the stack the operation is to effect.

Files

Creating a new file

	
CREATE.FILE filename filetype other

Filenames should be uppercase with words divided by periods (.)

other depends on the filetype being created Creating a new directory file

	
CREATE.FILE filename 1
CREATE.FILE filename 19

Creating a new static file

	
CREATE.FILE filename (2-18) modulo separation

modulo is the number of groups the file has. separation is the number of 512 bytes disk frames are allocated to each group

Maintaining a file

	
RESIZE filename newtype newmodulo newseparation

Creating a dynamic file

	
CREATE.FILE filename 30

Copy a file

	
COPY FROM sourcefile TO destfile ALL OVERWRITING

Editing Records

Editor Macros

Creating a new ED macro

@FILE variable can be used to be the existing file being edited. @ID variable can be used to be the key of the current record being edited. Example usage of @FILE and @ID within a macro

	
> ED &ED& MACRONAME				  
----: I
0001= E
0002= SAVE
0003= XEQ BASIC @FILE @ID
0004= XEQ RUN @FILE @ID
0005=

The VOC File

Creating a verb (command word)

	
> ED VOC verbname
----: I
0001= V
0002= programname
0003= type
0004=

All verbs start with a V. The name of the program to execute is specified by the second line. The type of the program is specified on the third line. Possible options are:

Creating a keyword (parameter or modified applied to verbs)

	
> ED VOC keywordname
----: I
0001= K
0002= value
0003= verbcommand (optional)

Keywords start with a K. Their second parameter is the value that gets substituted for the word. Creating a paragraph (script)

	
> ED VOC paragraphname
----: I
0001= PA
0002= script ....
0003= script ....

Paragraphs start with PA, then continue to define the script itself. For variables that are unknown at runtime the «…» syntax can be used to prompt the user inline for the value. Creating a sentence (a one line paragraph)

	
> ED VOC sentencename
----: I
0001= PA
0002= script ....

Creating a file pointer

	
> ED VOC filename
----: I
0001= F
0002= directoryname
0003= filename

Creating a qpointer

	
> ED VOC synonymname
----: I
0001= Q
0002= (space)
0003= filename

Creating a remote command

	
> ED VOC remotecommandname
----: I
0001= R
0002= filename that contains the command record
0003= key of the command record

Dictionaries

A description of common fields for a dictionary record

Creating a data field

	
> ED DICT filename fieldname
----: I
0001= D Description of the field
0002= field number
0003= conversion
0004= header
0005= format
0006= single or multi

Creating an imaginary field

		
> ED DICT filename fieldname
----: I
0001= I Description of the field
0002= formula
0003= conversion
0004= header
0005= format
0006= single or multi

Creating a phrase field

		
> ED DICT filename fieldname
----: I
0001= PH Description of the field
0002= fieldnames

Indexing Fields

RetrieVe

Criteria

Criteria can be reversed with NOT and concatenated with AND or OR.

Select Lists

TCL Commands

References

life, the universe, and everything