[PowerPC] Reading/Writing Memory

//Tutorial by BadLuckBrian

In this tutorial i will show you how Read and Write in the memory.

It's the same as 'PS3.GetMemory' and 'PS3.SetMemory' but it works a bit differently. Not really but its for the sake of understanding how it works !


Reading memory

We can read memory with 4 instructions.
Code:
lbz  (1 byte)
lhz  (2 bytes)
lwz  (4 bytes)
ld   (8 bytes)
we use them like this:

Code:
lwz RESULT, ADDRESS, TEMP_VAL

Result = register containing the byte at the address
ADDRESS = register containing the address to read from
TEMP_VAL= we can use it as a temporary 'addic'
example:

Code:
lis r3, 0xff           r3 = 00 ff 00 00   (0xff0000)
addic r3, r3, 0x1234    r3 = 00 ff 12 34  (0xff1234)
lwz r4, r3, 0            r4 = the first 4 bytes at 0xff1234
OR
Code:
lis r3, 0xff
lwz r4, r3, 0x1234       <- we use it as a temporary addic to save a line !!! but WARNING: on the next line r3 will be restored to 00 ff 00 00 while
using addic make it permanent !!!!
another example

reading the first 4 bytes at: 0x110d60c
Code:
lis r3, 0x0110
lwz r4, r3, 0xd60c
OR

Code:
lis r3, 0x0110
addic r3,r3, 0xd60c
lwz r4, r3, 0

Writing in the memory is as easy as reading it.

we will use:
Code:
stb   (1 byte)
sth   (2 bytes)
stw   (4 bytes)
std   (8 bytes)
we use them like this:
Code:
stw VALUE, ADDRESS, TEMP_VAL
example, i want to write 0x15 at: 0x2100000
Code:
lis r3, 0x210      (0x2100000) || 02 10 00 00
li r4, 0x15
stw r4, r3, 0
Another example would bwe to write 0x15 at: 0xFCA280

Code:
lis r3, 0xFC      (r3 = 00 FC 00 00)
li r4. 0x15
stw r4, r3, 0xA280   (0xFCA280)