Box Filter

Computer Organization and Assembly Language

Assignment #3

Box Filter

Virtual Boy Advance

„

An emulator for Nintendo Gameboy Advance

„

GBA - ARM7 architecture

Develop Environment

„ HAM GBA Devkit

„ http://www.ngine.de/index.jsp?pageid=3504

„ recommended

„ DevKit Advance

„ http://devkitadv.sourceforge.net/

„ Lightweight and simple

„ Base knowledge in writing Makefile required

Preparing

„

Download ham-280-full-win32.exe

„

Follow the instructions to install it

„

Download template files

„ http://w.csie.org/~r96051/hw3_template.rar

„ Extract to wherever you want

Replacing Makefile

„ In ($HAM_dir)/system/

„ Replacing

„ master.mak & standard-targets.mak

„ With these two files:

„ http://w.csie.org/~r96051/master.mak

„ http://w.csie.org/~r96051/standard- targets.mak

Getting start

„

Run ($HAM_dir)/vham/VHAM.exe

„

File -> Open workspace

„ open asm_hw3.vhw

„

Press ‘F7’ to Build and Run

Getting start

Box Filter

„ A spatial domain filter that

simply averaging pixel values in kernel.

„ Fixed 3x3 kernel for this assignment.

„ Notice: There are 2x2 kernel on corners, and 2x3 kernel on edges

Box Filter

Assignment

„

Modify myfilter.s as a box filter

„

void myfilter(u16* ret,const u16* ori);

„ ret and ori are two pointer to original and return images

„ ret in r0, ori in r1

myfilter.s

Auto Judge

„ Press Left, Up and

Down to switch between original image, filtered image and result.

„ Both accuracy and efficiency will be encountered when scoring.

Changing input

„

Replacing input.h for different input image.

„

You can use Gfx2gba making your own input image.

„ Gfx2gba 1.03

„ http://www.gbadev.org/tools.php?showinfo=143

Gfx2gba

„ Converting image file to C header file

„ See ReadMe.txt for usage information

BGR5 Format

„

15 bits for a pixel

„

5 bits for each BGR channel

„ Red channel at the lowest 5 bits

„ Green channel at bit6 to bit10

„ Blue channel at bit11 to bit15

„

Separating channels when blending

BGR5 Format

„ A straightforward C code for

blending

„ Is there a faster way?

Efficiency issue

„ Loop unrolling?

„ GBA memory :

„ 96KB VRAM

„ 32KB in-chip RAM

„ 256KB on-board RAM

„ Can we tiling?

„ Space and time : trade off

„ Are there duplicate adding? Can we reuse it?

Reference

„

More about GBA development:

„

GBADEV.org

„ http://www.gbadev.org/

„

Jonathan S. Harbour’s blog

„ http://theharbourfamily.com/jonathan/?page_id=89