Function Engine_stepFrameCables

src/engine/Engine.cpp:352–423

static void Engine_stepFrameCables(Engine* that) {
	auto finitize = [](float x) {
		return std::isfinite(x) ? x : 0.f;
	};

	// Iterate each cable input group, since `cables` is sorted by input
	auto firstIt = that->internal->cables.begin();
	while (firstIt != that->internal->cables.end()) {
		Cable* firstCable = *firstIt;
		Input* input = &firstCable->inputModule->inputs[firstCable->inputId];

		// Find end of input group
		auto endIt = firstIt;
		while (++endIt != that->internal->cables.end()) {
			Cable* endCable = *endIt;
			// Check inputId first since it changes more frequently between cables
			if (!(endCable->inputId == firstCable->inputId && endCable->inputModule == firstCable->inputModule))
				break;
		}

		// Since stackable inputs are uncommon, only use stackable input logic if there are multiple cables in input group.
		if (endIt - firstIt == 1) {
			Output* output = &firstCable->outputModule->outputs[firstCable->outputId];
			// Copy all voltages from output to input
			for (uint8_t c = 0; c < output->channels; c++) {
				input->voltages[c] = finitize(output->voltages[c]);
			}
			// Set higher channel voltages to 0
			for (uint8_t c = output->channels; c < input->channels; c++) {
				input->voltages[c] = 0.f;
			}
			input->channels = output->channels;
		}
		else {
			// Calculate max output channels
			uint8_t channels = 0;
			for (auto it = firstIt; it < endIt; ++it) {
				Cable* cable = *it;
				Output* output = &cable->outputModule->outputs[cable->outputId];
				channels = std::max(channels, output->channels);
			}

			// Clear input channels, including old channels
			for (uint8_t c = 0; c < std::max(channels, input->channels); c++) {
				input->voltages[c] = 0.f;
			}
			input->channels = channels;

			// Sum outputs of cables
			for (auto it = firstIt; it < endIt; ++it) {
				Cable* cable = *it;
				Output* output = &cable->outputModule->outputs[cable->outputId];

				// Sum monophonic value to all input channels
				if (output->channels == 1) {
					float value = finitize(output->voltages[0]);
					for (uint8_t c = 0; c < channels; c++) {
						input->voltages[c] += value;