Archive: 2009 october

2009-10-30 Linux assembler SDL

Open SDL window from asm. I tryed to open SDL window from asm. And that worked. Hardest thing is defining all structures from SDL headers. Windows opening and waiting while anykey will pressed.

include 'cdecl.inc'
 
format ELF
 
extrn SDL_Init
extrn SDL_SetVideoMode
extrn SDL_PollEvent
extrn SDL_Quit
 
;video settings
SDL_INIT_VIDEO	equ 0x00000020
SDL_FULLSCREEN	equ 0x80000000
 
;event settings
SDL_KEYDOWN         equ 2
SDL_MOUSEBUTTONDOWN equ 5
 
;programm settings
SCREEN_WIDTH equ 800
SCREEN_HEIGHT equ 600
SCREEN_BPP equ 24
 
struc SDL_keysym
{
	.scancode 	db 0
	.sym 		dd 0
	.mod		dd 0
	.unicode 	dd 0
}
 
struc SDL_KeyboardEvent
{
	.type  db 0
	.which db 0
	.state db 0
	.keysym SDL_keysym
}
 
struc SDL_Event
{
	.type db 0
	union SDL_KeyboardEvent
	.empty db 0,0,0
}
 
 
section '.text' executable
public _start
_start:
	ccall SDL_Init,SDL_INIT_VIDEO
	ccall SDL_SetVideoMode, SCREEN_WIDTH , SCREEN_HEIGHT , SCREEN_BPP , SDL_FULLSCREEN
	;try to make while loop
while_run:	
	while_polleEvent:
		ccall SDL_PollEvent, event
		cmp eax, 0
		je	while_polleEventquit
		cmp byte [event.type], SDL_KEYDOWN
		jne	while_polleEvent
		mov byte [run], 0
		jmp while_polleEvent
	while_polleEventquit:
 
	; if run != 1 quit
	cmp byte [run], 1	
	je	while_run
 
	ccall SDL_Quit, 0
 
	mov eax, 1
	xor ebx, ebx
	int 80h
 
section '.data' writeable
event		SDL_Event
run 		db 		1

Compile with lines:

fasm sdl.asm sdl.o

ld -dynamic-linker /lib/ld-linux.so.2 sdl.o /usr/lib/libSDL.so -o sdl

Dowload Source

2009-10-24 Making C executables smaller

There are some simple things that can be done to make C executables as small as possible.

Here is some example code we will work with:

#include <SDL/SDL.h>
 
char quit = 0;
 
int main()
{
    SDL_Surface *screen,surface;
    SDL_Event e;
    SDL_Init( SDL_INIT_VIDEO );
    screen = SDL_SetVideoMode( 400, 400, 32, SDL_SWSURFACE );
    while(!quit)
        while(SDL_PollEvent(&e)>0)
        {
            if(e.type==SDL_MOUSEBUTTONDOWN) quit=1;
            if(e.type==SDL_KEYDOWN) quit=1;
        }
    SDL_Quit();
}

Compile: gcc main.c -o main -lSDL

Size before: 5326 bytes

Execute command: strip main

strip is included in most unix systems. It deletes some info symbols from executables

Size after: 3532 bytes

You can also try sstrip which is advanced version of strip. You can download it from ELF kickers webpage.
Execute command: sstrip main

Size after: 1960 bytes

There are some others way to decrease size of programm.

GC Masher Allows to bruteforce gcc options for smaller executable size.
I where using this options for gcsmaher

-O  -O0  -O1  -O2  -O3  -Os
-ffast-math
-fomit-frame-pointer
-fauto-inc-dec
-mpush-args
-mno-red-zone
-mstackrealign

After runnig with this options executble size is 5175 bytes and best compiling options are all posible combination.

Combining with sstrip gives 1960 bytes.

And there size where not reduced but some time there can be saved some bytes.

Now we will change main function with

void _start()

and return change to

asm ( \
      "movl $1,%eax\n" \
      "xor %ebx,%ebx\n" \
      "int $128\n" \
    );

One other thing is to archive your executable and cat it with unpack shell script.

a=/tmp/I;tail -n+2 $0|zcat>$a;chmod +x $a;$a;rm $a;exit

Best options and smallest size now is 563 byte. Nope this is not smallest size try to

rename executable name to one symbol and you will get 4 extra bytes.

gcc -Os -ffast-math -fomit-frame-pointer 
-fauto-inc-dec -mpush-args -mno-red-zone -c small.c;
ld -dynamic-linker /lib/ld-linux.so.2 small.o /usr/lib/libSDL.so -o small;
strip -s -R .comment -R .gnu.version small;sstrip small;
7z a -tGZip -mx=9 small.gz small > /dev/null;
cat unpack.header small.gz > small;
chmod a+x small;rm small.gz small.o

Download Source

Rewriting all in asm gives 526 bytes Link.
Link to other resources Link1

Author in link has 634 bytes. With his options I have 622 bytes and using gcmasher i have 606 bytes. I have used his source in this compare.

2009-10-08 Basic HTTP server

Basic HTTP server. When you type url it shows listing of your local directory. If you tipe with path to file name noting hapens
Use:
http://*.*.*.*:/ -> disk start directory
http://*.*.*.*:/home/ -> home directory
Run:
./server port

Compile:
gcc server.c -o server

C Source

Here is also python source. It runs on port:8081 and prints in terminal HTTP request. You can see what browser sends to server.

Py Source

www.main.lv

Don't think just code it

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2009-10-30 Linux assembler SDL

2009-10-24 Making C executables smaller

2009-10-08 Basic HTTP server