timing_test.cpp

#include <3ds.h>
#include <stdio.h>

#include <cstdint>
#include <string>
#include <string_view>
#include <utility>
#include <vector>

static s64 base_tick;
static std::vector<std::pair<std::string_view, s64>> thread_order;

static volatile bool request_done = false;

static u64 first_tick = 0;
static u64 last_tick = 0;

int main(int argc, char **argv)
{
	gfxInitDefault();

	//Initialize console on top screen. Using NULL as the second argument tells the console library to use the internal console structure as current one
	consoleInit(GFX_TOP, NULL);

	y2rInit();

	printf("Timing test\n\n");

	svcSetThreadPriority(CUR_THREAD_HANDLE, 0x18);

	base_tick = svcGetSystemTick();

	int times = 0;

	FILE *dataSet = fopen("busy_loop_data.txt", "w");

	while (times++ < 10000) {

		Thread t = threadCreate([](void *arg) {
			last_tick = first_tick = svcGetSystemTick();

			// Busy looping low priority background thread
			// thread_order.emplace_back("Low priority background thread start", first_tick - base_tick);

			while (!request_done) {
				// Record the current tick
				last_tick = svcGetSystemTick();

				// Yield the thread to another thread
				svcSleepThread(0);
			}

			// thread_order.emplace_back("Low priority background thread done", svcGetSystemTick() - base_tick);
		}, nullptr, 0x1000, 0x19, 0, false);
		// thread_order.emplace_back("Created Low priority background thread", svcGetSystemTick() - base_tick);

		// thread_order.emplace_back("Call Performed", svcGetSystemTick() - base_tick);
		GSPGPU_SetLcdForceBlack(0);
		request_done = true; // Allow the thread to terminate whenever it gets rescheduled
		// thread_order.emplace_back("Call Done", svcGetSystemTick() - base_tick);

		threadJoin(t, U64_MAX);
		threadFree(t);

		// printf("Low Priority Thread Run Time: %lld - %lld\n", first_tick - base_tick, last_tick - base_tick);
		// printf("Low Priority Thread Run Duration: %lld\n", last_tick - first_tick);
		fprintf(dataSet, "%lld\n", last_tick - first_tick);

		hidScanInput();
		if (hidKeysDown() & KEY_START) break;

		request_done = false;

	}

	fclose(dataSet);

	printf("\nTimeline: \n");

	std::string str;
	for (auto &sv : thread_order) {
		str = sv.first;
		printf("%s: %lld\n", str.c_str(), sv.second);
	}

	printf("Press Start to exit.\n");

	// Main loop
	while (aptMainLoop())
	{
		//Scan all the inputs. This should be done once for each frame
		hidScanInput();

		//hidKeysDown returns information about which buttons have been just pressed (and they weren't in the previous frame)
		u32 kDown = hidKeysDown();

		if (kDown & KEY_START) break; // break in order to return to hbmenu

		// Flush and swap framebuffers
		gfxFlushBuffers();
		gfxSwapBuffers();

		//Wait for VBlank
		gspWaitForVBlank();
	}

	y2rExit();
	gfxExit();

	return 0;
}