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using a unique low level semaphore to prevent simultaneous access to pixel data #82

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using a unique low level semaphore to prevent simultaneous access to pixel data #82

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7bfb747
using a unique low level semaphore to prevent simultaneous access to …
limpkin Dec 23, 2025
9fa7a3d
Merge branch 'main' of https://github.com/limpkin/MoonLight
limpkin Dec 23, 2025
bca9991
actually use semaphores for what they're intended
limpkin Dec 23, 2025
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35 changes: 19 additions & 16 deletions src/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -114,8 +114,7 @@ ModuleLiveScripts moduleLiveScripts = ModuleLiveScripts(&server, &esp32sveltekit
ModuleChannels moduleChannels = ModuleChannels(&server, &esp32sveltekit);
ModuleMoonLightInfo moduleMoonLightInfo = ModuleMoonLightInfo(&server, &esp32sveltekit);

volatile xSemaphoreHandle effectSemaphore = xSemaphoreCreateBinary();
volatile xSemaphoreHandle driverSemaphore = xSemaphoreCreateBinary();
volatile xSemaphoreHandle lowLevelSemaphore = xSemaphoreCreateBinary();

TaskHandle_t effectTaskHandle = NULL;
TaskHandle_t driverTaskHandle = NULL;
Expand All @@ -128,20 +127,22 @@ void effectTask(void* pvParameters) {
for (;;) {
esp32sveltekit.lps++; // 🌙 todo: not moonlight specific?

if (xSemaphoreTake(effectSemaphore, pdMS_TO_TICKS(100)) == pdFALSE) {
if (xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100)) == pdFALSE) {
// EXT_LOGW(ML_TAG, "effectSemaphore wait too long"); //happens if no driver!, but let effects continue (for monitor) at 10 fps
//EXT_LOGW(ML_TAG, "effect: semaphore wait too long");
}
else {
layerP.loop(); // run all the effects of all virtual layers (currently only one layer)

layerP.loop(); // run all the effects of all virtual layers (currently only one layer)
static unsigned long last20ms = 0;
if (millis() - last20ms >= 20) {
last20ms = millis();
layerP.loop20ms();
}

static unsigned long last20ms = 0;
if (millis() - last20ms >= 20) {
last20ms = millis();
layerP.loop20ms();
xSemaphoreGive(lowLevelSemaphore);
}

xSemaphoreGive(driverSemaphore);

vTaskDelay(1); // yield to other tasks, 1 tick (~1ms)
}
}
Expand All @@ -152,12 +153,14 @@ void driverTask(void* pvParameters) {
// layerP.setup() done in effectTask

for (;;) {
xSemaphoreTake(driverSemaphore, pdMS_TO_TICKS(100));

layerP.loopDrivers();

xSemaphoreGive(effectSemaphore);
if (xSemaphoreTake(lowLevelSemaphore, pdMS_TO_TICKS(100)) == pdFALSE) {
//EXT_LOGW(ML_TAG, "driver: semaphore wait too long");
}
else {
layerP.loopDrivers();

xSemaphoreGive(lowLevelSemaphore);
}
vTaskDelay(1); // yield to other tasks, 1 tick (~1ms)
}
}
Expand Down Expand Up @@ -325,7 +328,7 @@ void setup() {
false);
#endif

xSemaphoreGive(effectSemaphore); // Allow effectTask to run first
xSemaphoreGive(lowLevelSemaphore);

// 🌙
xTaskCreateUniversal(effectTask, // task function
Expand Down