b8d43d4dfb
Uses arithmetic that can be identified more trivially by compilers for
optimizations. e.g. Rather than shifting the halves of the value and
then swapping and combining them, we can swap them in place.
e.g. for the original swap32 code on x86-64, clang 8.0 would generate:
mov ecx, edi
rol cx, 8
shl ecx, 16
shr edi, 16
rol di, 8
movzx eax, di
or eax, ecx
ret
while GCC 8.3 would generate the ideal:
mov eax, edi
bswap eax
ret
now both generate the same optimal output.
MSVC used to generate the following with the old code:
mov eax, ecx
rol cx, 8
shr eax, 16
rol ax, 8
movzx ecx, cx
movzx eax, ax
shl ecx, 16
or eax, ecx
ret 0
Now MSVC also generates a similar, but equally optimal result as clang/GCC:
bswap ecx
mov eax, ecx
ret 0
====
In the swap64 case, for the original code, clang 8.0 would generate:
mov eax, edi
bswap eax
shl rax, 32
shr rdi, 32
bswap edi
or rax, rdi
ret
(almost there, but still missing the mark)
while, again, GCC 8.3 would generate the more ideal:
mov rax, rdi
bswap rax
ret
now clang also generates the optimal sequence for this fallback as well.
This is a case where MSVC unfortunately falls short, despite the new
code, this one still generates a doozy of an output.
mov r8, rcx
mov r9, rcx
mov rax, 71776119061217280
mov rdx, r8
and r9, rax
and edx, 65280
mov rax, rcx
shr rax, 16
or r9, rax
mov rax, rcx
shr r9, 16
mov rcx, 280375465082880
and rax, rcx
mov rcx, 1095216660480
or r9, rax
mov rax, r8
and rax, rcx
shr r9, 16
or r9, rax
mov rcx, r8
mov rax, r8
shr r9, 8
shl rax, 16
and ecx, 16711680
or rdx, rax
mov eax, -16777216
and rax, r8
shl rdx, 16
or rdx, rcx
shl rdx, 16
or rax, rdx
shl rax, 8
or rax, r9
ret 0
which is pretty unfortunate.
|
||
|---|---|---|
| .appveyor | ||
| .github | ||
| .travis | ||
| CMakeModules | ||
| dist | ||
| externals | ||
| hooks | ||
| src | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .travis.yml | ||
| appveyor.yml | ||
| bitrise.yml | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| Doxyfile | ||
| keys.tar.enc | ||
| license.txt | ||
| README.md | ||
BEFORE FILING AN ISSUE, READ THE RELEVANT SECTION IN THE CONTRIBUTING FILE!!!
Citra
Citra is an experimental open-source Nintendo 3DS emulator/debugger written in C++. It is written with portability in mind, with builds actively maintained for Windows, Linux and macOS.
Citra emulates a subset of 3DS hardware and therefore is useful for running/debugging homebrew applications, and it is also able to run many commercial games! Some of these do not run at a playable state, but we are working every day to advance the project forward. (Playable here means compatibility of at least "Okay" on our game compatibility list.)
Citra is licensed under the GPLv2 (or any later version). Refer to the license.txt file included. Please read the FAQ before getting started with the project.
Check out our website!
For development discussion, please join us at #citra-dev on freenode.
Development
Most of the development happens on GitHub. It's also where our central repository is hosted.
If you want to contribute please take a look at the Contributor's Guide and Developer Information. You should as well contact any of the developers in the forum in order to know about the current state of the emulator because the TODO list isn't maintained anymore.
If you want to contribute to the user interface translation, please checkout citra project on transifex. We centralize the translation work there, and periodically upstream translation.
Building
- Windows: Windows Build
- Linux: Linux Build
- macOS: macOS Build
Support
We happily accept monetary donations or donated games and hardware. Please see our donations page for more information on how you can contribute to Citra. Any donations received will go towards things like:
- 3DS consoles for developers to explore the hardware
- 3DS games for testing
- Any equipment required for homebrew
- Infrastructure setup
- Eventually 3D displays to get proper 3D output working
We also more than gladly accept used 3DS consoles, preferably ones with firmware 4.5 or lower! If you would like to give yours away, don't hesitate to join our IRC channel #citra on Freenode and talk to neobrain or bunnei. Mind you, IRC is slow-paced, so it might be a while until people reply. If you're in a hurry you can just leave contact details in the channel or via private message and we'll get back to you.