src/joystick/hidapi/SDL_hidapi_rumble.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2023 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_JOYSTICK_HIDAPI

/* Handle rumble on a separate thread so it doesn't block the application */

#include "SDL_thread.h"
#include "SDL_timer.h"
#include "SDL_hidapijoystick_c.h"
#include "SDL_hidapi_rumble.h"
#include "../../thread/SDL_systhread.h"


typedef struct SDL_HIDAPI_RumbleRequest
{
    SDL_HIDAPI_Device *device;
    Uint8 data[2*USB_PACKET_LENGTH]; /* need enough space for the biggest report: dualshock4 is 78 bytes */
    int size;
    SDL_HIDAPI_RumbleSentCallback callback;
    void *userdata;
    struct SDL_HIDAPI_RumbleRequest *prev;

} SDL_HIDAPI_RumbleRequest;

typedef struct SDL_HIDAPI_RumbleContext
{
    SDL_atomic_t initialized;
    SDL_atomic_t running;
    SDL_Thread *thread;
    SDL_mutex *lock;
    SDL_sem *request_sem;
    SDL_HIDAPI_RumbleRequest *requests_head;
    SDL_HIDAPI_RumbleRequest *requests_tail;
} SDL_HIDAPI_RumbleContext;

static SDL_HIDAPI_RumbleContext rumble_context;

static int SDLCALL SDL_HIDAPI_RumbleThread(void *data)
{
    SDL_HIDAPI_RumbleContext *ctx = (SDL_HIDAPI_RumbleContext *)data;

    SDL_SetThreadPriority(SDL_THREAD_PRIORITY_HIGH);

    while (SDL_AtomicGet(&ctx->running)) {
        SDL_HIDAPI_RumbleRequest *request = NULL;

        SDL_SemWait(ctx->request_sem);

        SDL_LockMutex(ctx->lock);
        request = ctx->requests_tail;
        if (request) {
            if (request == ctx->requests_head) {
                ctx->requests_head = NULL;
            }
            ctx->requests_tail = request->prev;
        }
        SDL_UnlockMutex(ctx->lock);

        if (request) {
            SDL_LockMutex(request->device->dev_lock);
            if (request->device->dev) {
#ifdef DEBUG_RUMBLE
                HIDAPI_DumpPacket("Rumble packet: size = %d", request->data, request->size);
#endif
                SDL_hid_write(request->device->dev, request->data, request->size);
            }
            SDL_UnlockMutex(request->device->dev_lock);
            if (request->callback) {
                request->callback(request->userdata);
            }
            (void)SDL_AtomicDecRef(&request->device->rumble_pending);
            SDL_free(request);

            /* Make sure we're not starving report reads when there's lots of rumble */
            SDL_Delay(10);
        }
    }
    return 0;
}

static void
SDL_HIDAPI_StopRumbleThread(SDL_HIDAPI_RumbleContext *ctx)
{
    SDL_HIDAPI_RumbleRequest *request;

    SDL_AtomicSet(&ctx->running, SDL_FALSE);

    if (ctx->thread) {
        int result;

        SDL_SemPost(ctx->request_sem);
        SDL_WaitThread(ctx->thread, &result);
        ctx->thread = NULL;
    }

    SDL_LockMutex(ctx->lock);
    while (ctx->requests_tail) {
        request = ctx->requests_tail;
        if (request == ctx->requests_head) {
            ctx->requests_head = NULL;
        }
        ctx->requests_tail = request->prev;

        if (request->callback) {
            request->callback(request->userdata);
        }
        (void)SDL_AtomicDecRef(&request->device->rumble_pending);
        SDL_free(request);
    }
    SDL_UnlockMutex(ctx->lock);

    if (ctx->request_sem) {
        SDL_DestroySemaphore(ctx->request_sem);
        ctx->request_sem = NULL;
    }

    if (ctx->lock) {
        SDL_DestroyMutex(ctx->lock);
        ctx->lock = NULL;
    }

    SDL_AtomicSet(&ctx->initialized, SDL_FALSE);
}

static int
SDL_HIDAPI_StartRumbleThread(SDL_HIDAPI_RumbleContext *ctx)
{
    ctx->lock = SDL_CreateMutex();
    if (!ctx->lock) {
        SDL_HIDAPI_StopRumbleThread(ctx);
        return -1;
    }

    ctx->request_sem = SDL_CreateSemaphore(0);
    if (!ctx->request_sem) {
        SDL_HIDAPI_StopRumbleThread(ctx);
        return -1;
    }

    SDL_AtomicSet(&ctx->running, SDL_TRUE);
    ctx->thread = SDL_CreateThreadInternal(SDL_HIDAPI_RumbleThread, "HIDAPI Rumble", 0, ctx);
    if (!ctx->thread) {
        SDL_HIDAPI_StopRumbleThread(ctx);
        return -1;
    }
    return 0;
}

int SDL_HIDAPI_LockRumble(void)
{
    SDL_HIDAPI_RumbleContext *ctx = &rumble_context;

    if (SDL_AtomicCAS(&ctx->initialized, SDL_FALSE, SDL_TRUE)) {
        if (SDL_HIDAPI_StartRumbleThread(ctx) < 0) {
            return -1;
        }
    }

    return SDL_LockMutex(ctx->lock);
}

SDL_bool SDL_HIDAPI_GetPendingRumbleLocked(SDL_HIDAPI_Device *device, Uint8 **data, int **size, int *maximum_size)
{
    SDL_HIDAPI_RumbleContext *ctx = &rumble_context;
    SDL_HIDAPI_RumbleRequest *request, *found;

    found = NULL;
    for (request = ctx->requests_tail; request; request = request->prev) {
        if (request->device == device) {
            found = request;
        }
    }
    if (found) {
        *data = found->data;
        *size = &found->size;
        *maximum_size = sizeof(found->data);
        return SDL_TRUE;
    }
    return SDL_FALSE;
}

int SDL_HIDAPI_SendRumbleAndUnlock(SDL_HIDAPI_Device *device, const Uint8 *data, int size)
{
    return SDL_HIDAPI_SendRumbleWithCallbackAndUnlock(device, data, size, NULL, NULL);
}

int SDL_HIDAPI_SendRumbleWithCallbackAndUnlock(SDL_HIDAPI_Device *device, const Uint8 *data, int size, SDL_HIDAPI_RumbleSentCallback callback, void *userdata)
{
    SDL_HIDAPI_RumbleContext *ctx = &rumble_context;
    SDL_HIDAPI_RumbleRequest *request;

    if (size > sizeof(request->data)) {
        SDL_HIDAPI_UnlockRumble();
        return SDL_SetError("Couldn't send rumble, size %d is greater than %d", size, (int)sizeof(request->data));
    }

    request = (SDL_HIDAPI_RumbleRequest *)SDL_calloc(1, sizeof(*request));
    if (!request) {
        SDL_HIDAPI_UnlockRumble();
        return SDL_OutOfMemory();
    }
    request->device = device;
    SDL_memcpy(request->data, data, size);
    request->size = size;
    request->callback = callback;
    request->userdata = userdata;

    SDL_AtomicIncRef(&device->rumble_pending);
    
    if (ctx->requests_head) {
        ctx->requests_head->prev = request;
    } else {
        ctx->requests_tail = request;
    }
    ctx->requests_head = request;

    /* Make sure we unlock before posting the semaphore so the rumble thread can run immediately */
    SDL_HIDAPI_UnlockRumble();

    SDL_SemPost(ctx->request_sem);

    return size;
}

void SDL_HIDAPI_UnlockRumble(void)
{
    SDL_HIDAPI_RumbleContext *ctx = &rumble_context;

    SDL_UnlockMutex(ctx->lock);
}

int SDL_HIDAPI_SendRumble(SDL_HIDAPI_Device *device, const Uint8 *data, int size)
{
    Uint8 *pending_data;
    int *pending_size;
    int maximum_size;

    if (size <= 0) {
        return SDL_SetError("Tried to send rumble with invalid size");
    }

    if (SDL_HIDAPI_LockRumble() < 0) {
        return -1;
    }

    /* check if there is a pending request for the device and update it */
    if (SDL_HIDAPI_GetPendingRumbleLocked(device, &pending_data, &pending_size, &maximum_size) &&
        size == *pending_size && data[0] == pending_data[0]) {
        SDL_memcpy(pending_data, data, size);
        SDL_HIDAPI_UnlockRumble();
        return size;
    }

    return SDL_HIDAPI_SendRumbleAndUnlock(device, data, size);
}

void SDL_HIDAPI_QuitRumble(void)
{
    SDL_HIDAPI_RumbleContext *ctx = &rumble_context;

    if (SDL_AtomicGet(&ctx->running)) {
        SDL_HIDAPI_StopRumbleThread(ctx);
    }
}

#endif /* SDL_JOYSTICK_HIDAPI */

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