Coding Questions and other Quandaries

File

Line

Function

/inc/class_error.php

153

errorHandler->error

/printthread.php(287) : eval()'d code

errorHandler->error_callback

/printthread.php

287

eval

/printthread.php

117

printthread_multipage

Code:

andi. r12, r29, 0x000F #This will AND with a value of 0x0000000F. All binary values in the final Hex digit are preserved. The dot in the instruction operand is required in the andi instruction because the Broadway CPU developers never made a version of the andi instruction without the dot. The dot isn't applicable to us in this situation but it's a free use of cmpwi rD, 0. 



cmpwi r12, 4 #Check if Address ends in the digit 4.

bne- default_instruction #If not, it's not an address for Celia, don't execute



li r3, 0xC8 #Update Celia's health



default_instruction:

stw r3, 0x0014 (r29) #Store health to dynamic memory

Code:

#IABR compiler statement

.set IABR, 1010



#Set First Loop Load Address

lis r3, 0x807A



#Search will be from 0x807A0000 thru 0x807C0000

#Set amount of times to search (0x20000 bytes / 4 = 0x8000 words); so we'll set the amount to 0x7FFF to scrap the one search so we can save one insruction on the source, lul

li r0, 0x7FFF

mtctr r0



#Set the crude checksum

#480012CD (before default instruction) XOR'd with 90770020 (default insruction) = D87712ED

lis r5, 0xD877

ori r5, r5, 0x12ED



#Loop

loop:



#Load double word at r3, and then increment r3 by 4

lwz r11, 0 (r3)

lwzu r12, 0x4 (r3)



#Xor double word together; compare XOR checksums

xor r0, r11, r12

cmpw r5, r0

beq- found



#not yet found, keep trying

bdnz+ loop

blr #If no find, end C0. Do NOT update EVA nor IABR



#Found it!

found:

#Flip bits of 30 and 31 high, this is needed for IABR (BE and TE)

ori r3, r3, 0x0003

mtspr IABR, r3 #Broadway says we need a context-synchronizing instruction after this but considering there's a huge amount of time from when this instruction executes to when the IABR is taken, its not needed

#blr #End C0; uncomment if NOT using pyiiasmh and then adjust compiled code so it can be a proper C0

Code:

li r3, 9 #Set the shared item

clrlwi r12, r23, 1 #Change r23's address to physical

stw r3, 0x0020 (r12) #Update new item

mfsrr0 r12 #Grab address that IABR triggered on

addi r12, r12, 4 #We must increment to return back to shared item adress+4. Or else the IABR will be triggered again and we will be in a infinite loop

mtsrr0 r12 #Update new srr0 (address to go to when exception is over)

rfi #END EXCEPTION!

Code:

lwz r12, 0x0014 (r29)

cmpwi r12, 0xC8

beq- celia_health #You are branching literally to the next instruction, this is a useless branch



celia_health:

li r12, 0 #r12's value is going to be overwritten by the andi. instruction. So this li instruction has zero effect

andi. r12, r29, 0xF

cmpwi r12, 0

bne- default_instruction

li r3, 0xC8



default_instruction:

stw r3, 0x0014 (r29)

Code:

#First check the last digit of the Health Address

addi r12, r29, 0x0014 #increment r29's mem address by value of 0x0014

andi. r12, r12, 0xF

cmpwi r12, 0x4

bne- default_instruction



#Check if Health Value 0xC8 is initially present

lwz r12, 0x0014 (r29)

cmpwi r12, 0xC8

bne- default_instruction



#Keep Celia's health at 0xC8

mr r3, r12



#Default Instruction, update the Health

default_instruction:

stw r3, 0x0014 (r29)

Code:

addi r12, r29, 0x0014 #increment r29's mem address by value of 0x0014

andi. r12, r12, 0xF

cmpwi r12, 0x4

bne- default_instruction

li r3, 0xC8

default_instruction:

stw r3, 0x0014 (r29)