Assembler Tutorial

The type of Assembly that the Gecko writes to the Wii's RAM is "PPC" or "PowerPC". So, keep that mind when or if you want to learn ASM to hack Wii games.  

ASM was created in the 1950s and is still used in every program and computer ever made, including phones, consoles, files, etc. Why? Because it still works! So, this obviously isn't easy to use, especially for n00bs.

Every programmer/hacker knows what "Hello World" is, but every language has it's different structures and syntax for producing the same result. Below is an example of a Hello World program written in Boo, which is very easy to understand even for a n00b. And one written in ASM for the Z80 Computer/Game Console.

Code:


# Hello World in Boo
print "Hello World"


Code:

; This is a "Hello World" program for Z80 and TMS9918 / TMS9928 / TMS9929 /
; V9938 or V9958 VDP.
; That means that this should work on SVI, MSX, Colecovision, Memotech,
; and many other Z80 based home computers or game consoles.
;
; Because we don't know what system is used, we don't know where RAM
; is, so we can't use stack in this program.
;
; This version of Hello World was written by Timo "NYYRIKKI" Soilamaa
; 17.10.2001
;
;----------------------------------------------------------------------
; Configure this part:

DATAP: EQU #98 ; VDP Data port #98 works on all MSX models
; (TMS9918/TMS9929/V9938 or V9958)
; #80 works on SVI
; (for other platforms you have to figure this out by your self)

CMDP: EQU #99 ; VDP Command port #99 works on all MSX models
; (TMS9918/TMS9929/V9938 or V9958)
; #81 works on SVI
; (for other platforms you have to figure this out by your self)
;-----------------------------------------------------------------------
; Program starts here:

ORG 0 ; Z80 starts always from here when power is turned on
DI ; We don't know, how interrupts works in this system, so we disable them.

; Let's set VDP write address to #0000
XOR A
OUT (CMDP),A
LD A,#40
OUT (CMDP),A

; Now let's clear first 16Kb of VDP memory
LD B,0
LD HL,#3FFF
LD C,DATAP
CLEAR:
OUT (C),B
DEC HL
LD A,H
OR L
NOP ; Let's wait 8 clock cycles just in case VDP is not quick enough.
NOP
JR NZ,CLEAR

; Now it is time to set up VDP registers:
;----------------------------------------
; Register 0 to #0
;
; Set mode selection bit M3 (maybe also M4 & M5) to zero and
; disable external video & horizontal interrupt
LD C,CMDP
LD E,#80

OUT (C),A
OUT (C),E
;----------------------------------------
; Register 1 to #50
;
; Select 40 column mode, enable screen and disable vertical interrupt

LD A,#50
INC E
OUT (C),A
OUT (C),E
;----------------------------------------
; Register 2 to #0
;
; Set pattern name table to #0000

XOR A
INC E
OUT (C),A
OUT (C),E
;----------------------------------------
; Register 3 is ignored as 40 column mode does not need color table
;
INC E
;----------------------------------------
; Register 4 to #1
; Set pattern generator table to #800

INC A
INC E

OUT (C),A
OUT (C),E
;----------------------------------------
; Registers 5 (Sprite attribute) & 6 (Sprite pattern) are ignored
; as 40 column mode does not have sprites

INC E
INC E
;----------------------------------------
; Register 7 to #F0
; Set colors to white on black

LD A,#F0
INC E
OUT (C),A
OUT (C),E
;----------------------------------------

; Let's set VDP write address to #808 so, that we can write
; character set to memory
; (No need to write SPACE it is clear char already)
LD A,8
OUT (C),A
LD A,#48
OUT (C),A

; Let's copy character set
LD HL,CHARS
LD B, CHARS_END-CHARS
COPYCHARS:
LD A,(HL)
OUT (DATAP),A
INC HL
NOP ; Let's wait 8 clock cycles just in case VDP is not quick enough.
NOP
DJNZ COPYCHARS

; Let's set write address to start of name table
XOR A
OUT (C),A
LD A,#40
OUT (C),A

; Let's put characters to screen
LD HL,ORDER
LD B,ORDER_END-ORDER
COPYORDER:
LD A,(HL)
OUT (DATAP),A
INC HL

JR OVERNMI
NOP
NOP

; Here is address #66, that is entry for NMI
RETN ;Return from NMI

OVERNMI:
DJNZ COPYORDER

; The end
HALT

; Character set:
; --------------
ORDER:
DEFB 1,2,3,3,4,0,5,4,6,3,7
ORDER_END:

CHARS:

; H
DEFB %10001000
DEFB %10001000
DEFB %10001000
DEFB %11111000
DEFB %10001000
DEFB %10001000
DEFB %10001000
DEFB %00000000
; e
DEFB %00000000
DEFB %00000000
DEFB %01110000
DEFB %10001000
DEFB %11111000
DEFB %10000000
DEFB %01110000
DEFB %00000000
; l
DEFB %01100000
DEFB %00100000
DEFB %00100000
DEFB %00100000
DEFB %00100000
DEFB %00100000
DEFB %01110000
DEFB %00000000
; o
DEFB %00000000
DEFB %00000000
DEFB %01110000
DEFB %10001000
DEFB %10001000
DEFB %10001000
DEFB %01110000
DEFB %00000000
; W
DEFB %10001000
DEFB %10001000
DEFB %10001000
DEFB %10101000
DEFB %10101000
DEFB %11011000
DEFB %10001000
DEFB %00000000

; r
DEFB %00000000
DEFB %00000000
DEFB %10110000
DEFB %11001000
DEFB %10000000
DEFB %10000000
DEFB %10000000
DEFB %00000000
; d
DEFB %00001000
DEFB %00001000
DEFB %01101000
DEFB %10011000
DEFB %10001000
DEFB %10011000
DEFB %01101000
DEFB %00000000
chars_end:


See the difference? 500 lines of Gibberish (??? bytes total) produces the same result as 1 English-like lines (19 bytes total)! It's a very difficult language to learn, even for expert programmers and no one programs with it anymore. But if you can actually master it, which I doubt anyone could lol, you can do almost anything with a computer!

Anyways, here's the tutorial!  xD

http://wiibrew.org/wiki/Assembler_Tutorial

This is why high level languages have been invented. On a high level of abstraction you write code and it is translated into ASM gibberish. :3

Also the reason why complex Wii hacks are hard. Abstraction doesn't really exist, it's assembly based.