Can someone please explain to me what the instructions mtctr and dcbst mean Because i have been trying to reverse this mtctr r4 and dcbst r0, r3 Please Help.
mtctr is the move to count register instruction. It's moving the value in r4 to the count register. Regarding the count register, the PowerPC User Instruction Set Architecture Book 1 says:
The Count Register (CTR) is a 64-bit register. It can be used to hold a loop count that can be decremented dur- ing execution of Branch instructions that contain an appropriately coded BO field.
So, if you are trying to translate from assembly to C/C++ this instruction could be associated with a for loop or other looping mechanism with a count.
dcbst is the data cache block store instruction. This instruction is used to manage the data cache (versus the instruction cache) of the processor. If the effective address calculated with r0 and r3 specified is in a local data cache of any processor, then it will be written out to storage. It could be part of services provided by an operating system. For more detail, see the PowerPC User Instruction Set Architecture Book 2.