mirror
/
SDL
mirror of https://github.com/libsdl-org/SDL.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Delete src/thread/n3ds/SDL_syscond.c 

This PR removes the incorrect implementation of `SDL_cond` currently included with the 3DS port.

Pseudocode of the incorrect implementation of `SDL_CondWait` this PR removes:

* Receive an `SDL_cond` backed by a `libctru` `CondVar` and an `SDL_mutex` backed by a `libctru` `RecursiveLock`.
* Want to call `libctru` function `CondVar_Wait` which expects a `CondVar` and a `LightLock` (non-recursive lock)
* Do so by calling this function with the internal (inadequately protected) `LightLock` member of the `RecursiveLock` (`&mutex->lock.lock` on line 105), without updating any internal thread or lock count fields of the `RecursiveLock`.

Happy to discuss or test some examples. My own use case works much better with the generic cond logic, and this seems like a safe fix to me given that the generic logic is well-tested and this seems not to be.

If you like the PR I'll send another one for the SDL2 branch.
This commit is contained in:
ds-sloth 2025-01-28 23:14:56 -05:00 committed by Sam Lantinga
parent 7af17f874c
commit 2ced6b09fc
1 changed files with 0 additions and 111 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

111
src/thread/n3ds/SDL_syscond.c
View File

@ -1,111 +0,0 @@
/*
Simple DirectMedia Layer
Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_internal.h"
#ifdef SDL_THREAD_N3DS
// An implementation of condition variables using libctru's CondVar
#include "SDL_sysmutex_c.h"
struct SDL_Condition
{
CondVar cond_variable;
};
// Create a condition variable
SDL_Condition *SDL_CreateCondition(void)
{
SDL_Condition *cond = (SDL_Condition *)SDL_malloc(sizeof(SDL_Condition));
if (cond) {
CondVar_Init(&cond->cond_variable);
}
return cond;
}
// Destroy a condition variable
void SDL_DestroyCondition(SDL_Condition *cond)
{
if (cond) {
SDL_free(cond);
}
}
// Restart one of the threads that are waiting on the condition variable
void SDL_SignalCondition(SDL_Condition *cond)
{
if (!cond) {
return;
}
CondVar_Signal(&cond->cond_variable);
}
// Restart all threads that are waiting on the condition variable
void SDL_BroadcastCondition(SDL_Condition *cond)
{
if (!cond) {
return;
}
CondVar_Broadcast(&cond->cond_variable);
}
/* Wait on the condition variable for at most 'timeoutNS' nanoseconds.
The mutex must be locked before entering this function!
The mutex is unlocked during the wait, and locked again after the wait.
Typical use:
Thread A:
SDL_LockMutex(lock);
while ( ! condition ) {
SDL_WaitCondition(cond, lock);
}
SDL_UnlockMutex(lock);
Thread B:
SDL_LockMutex(lock);
...
condition = true;
...
SDL_SignalCondition(cond);
SDL_UnlockMutex(lock);
*/
bool SDL_WaitConditionTimeoutNS(SDL_Condition *cond, SDL_Mutex *mutex, Sint64 timeoutNS)
{
Result res;
if (!cond || !mutex) {
return true;
}
res = 0;
if (timeoutNS < 0) {
CondVar_Wait(&cond->cond_variable, &mutex->lock.lock);
} else {
res = CondVar_WaitTimeout(&cond->cond_variable, &mutex->lock.lock, timeoutNS);
}
return R_SUCCEEDED(res);
}
#endif // SDL_THREAD_N3DS