Typically when someone uses GetPointer, it's because they want to read
from a range of memory. GetPointer is unsafe to use for this. While it
does check that the passed-in address is valid, it doesn't know the size
of the range that will be accessed, so it can't check that the end
address is valid. The safer alternative GetPointerForRange should be
used instead.
Note that there is still the problem of many callers not checking for
nullptr.
This is the first part of a series of changes that will remove the usage
of GetPointer in different parts of the code base. This commit gets rid
of every GetPointer call from our IOS code except for a particularly
tricky one in BluetoothEmuDevice.
Not sure if the behavior I'm implementing here is what real hardware
does, but since this is a buffer overflow, I'd like to get it fixed
quickly. Hardware verification can happen later.
https://bugs.dolphin-emu.org/issues/13506
Having to look up macros that are defined elsewhere makes the code
harder to reason about. The macros don't remove enough repetition to
justify their existence in my opinion.
When the divisor is a constant value, we can emit more efficient code.
For powers of two, we can use bit shifts. For other values, we can
instead use a multiplication by magic constant method.
- Example 1 - Division by 16 (power of two)
Before:
mov w24, #0x10 ; =16
udiv w27, w25, w24
After:
lsr w27, w25, #4
- Example 2 - Division by 10 (fast)
Before:
mov w25, #0xa ; =10
udiv w27, w26, w25
After:
mov w27, #0xcccd ; =52429
movk w27, #0xcccc, lsl #16
umull x27, w26, w27
lsr x27, x27, #35
- Example 3 - Division by 127 (slow)
Before:
mov w26, #0x7f ; =127
udiv w27, w27, w26
After:
mov w26, #0x408 ; =1032
movk w26, #0x8102, lsl #16
umaddl x27, w27, w26, x26
lsr x27, x27, #38
This implements the GameCube modem adapter. This implementation is stable but not perfect; it drops frames if the receive FIFO length is exceeded. This is probably due to the unimplemented interrupt mentioned in the comments. If the tapserver end of the connection is aware of this limitation, it's easily circumvented by lowering the MTU of the link, but ideally this wouldn't be necessary.
This has been tested with a couple of different versions of Phantasy Star Online, including Episodes 1 & 2 Trial Edition. The Trial Edition is the only version of the game that supports the Modem Adapter and not the Broadband Adapter, which is what made this commit necessary in the first place.
This expands the tapserver BBA interface to be available on all platforms. tapserver itself is still macOS-only, but newserv (the PSO server) is not, and it can directly accept local and remote tapserver connections as well. This makes the tapserver interface potentially useful on all platforms.