fps limit

inc/lzy.h

@@ -7,7 +7,7 @@ extern "C" {
 
 #define LZY_UNUSED(x) (void)(x)
 
-int LZY_Init(const char *title);
+int LZY_Init(const char *title, int target_fps);
 void LZY_Quit(void);
 int LZY_DrawBegin(void);
 int LZY_DrawEnd(void);
@@ -56,19 +56,40 @@ enum LZY_ScanCode {
 #endif
 
 #ifdef FXCG50
+#include <gint/cpu.h>
 #include <gint/display.h>
 #include <gint/keyboard.h>
+#include <gint/timer.h>
 #include <stdint.h>
 
 static color_t draw_color = C_BLACK;
 static int should_quit = 0;
+static int timer = 0;
+static volatile int has_ticked = 0;
 
-int LZY_Init(const char *title) {
+static int timer_callback(volatile int *);
+
+int LZY_Init(const char *title, int target_fps) {
 	LZY_UNUSED(title);
+	if (target_fps > 0) {
+		timer = timer_configure(TIMER_ANY, 1000000 / target_fps,
+		                        GINT_CALL(timer_callback, &has_ticked));
+		timer_start(timer);
+	}
 	return 0;
 }
 
-void LZY_Quit(void) {}
+static int timer_callback(volatile int *arg) {
+	*arg += 1;
+	return 0;
+}
+
+void LZY_Quit(void) {
+	if (timer) {
+		timer_stop(timer);
+		timer = 0;
+	}
+}
 
 int LZY_DrawBegin(void) {
 	return 0;
@@ -76,11 +97,14 @@ int LZY_DrawBegin(void) {
 
 int LZY_DrawEnd(void) {
 	dupdate();
+	while (timer && !has_ticked)
+		sleep();
+	has_ticked = 0;
 	return 0;
 }
 
 void LZY_DrawSetColor(uint8_t r, uint8_t g, uint8_t b) {
-	draw_color = C_RGB(r << 3, g << 3, b << 3);
+	draw_color = C_RGB(r / 8, g / 8, b / 8);
 }
 
 void LZY_DrawSetColorNone(void) {
@@ -122,8 +146,11 @@ static SDL_Window *window = NULL;
 static SDL_Renderer *renderer = NULL;
 static int should_quit = 0;
 static int input[LZYK_COUNT] = {0};
+static int fps_limiter = 0;
+static uint64_t min_dt;
+static uint64_t next_time;
 
-int LZY_Init(const char *title) {
+int LZY_Init(const char *title, int target_fps) {
 	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
 		error = SDL_GetError();
 		return 1;
@@ -147,6 +174,12 @@ int LZY_Init(const char *title) {
 		return 3;
 	}
 
+	fps_limiter = target_fps > 0;
+	if (fps_limiter) {
+		min_dt = 1000 / target_fps;
+		next_time = SDL_GetTicks64();
+	}
+
 	return 0;
 }
 
@@ -165,11 +198,21 @@ void LZY_Quit(void) {
 }
 
 int LZY_DrawBegin(void) {
+	if (fps_limiter)
+		next_time += min_dt;
 	return 0;
 }
 
 int LZY_DrawEnd(void) {
 	SDL_RenderPresent(renderer);
+
+	if (fps_limiter) {
+		const uint64_t cur_time = SDL_GetTicks64();
+		if (next_time <= cur_time)
+			next_time = cur_time;
+		else
+			SDL_Delay(next_time - cur_time);
+	}
 	return 0;
 }
 

src/main.c

@@ -1,26 +1,28 @@
 #define LZY_IMPLEMENTATION
 #include "lzy.h"
+#include <stdint.h>
 
 int main(void) {
-	if (LZY_Init("lzy example")) {
+	uint8_t c = 0;
+
+	if (LZY_Init("lzy example", 30)) {
 		LZY_Log(LZY_GetError());
 		LZY_Quit();
 		return 1;
 	}
 	LZY_Log("init was great success!");
 
-	LZY_DrawSetColor(0xff, 0xff, 0x00);
-
-	LZY_DrawBegin();
-	LZY_DrawClear();
-	LZY_DrawEnd();
-
 	do {
 		LZY_CycleEvents();
 		if (LZY_KeyDown(LZYK_LEFT))
-			LZY_Log("pressing left");
+			c -= 8;
 		if (LZY_KeyDown(LZYK_RIGHT))
-			LZY_Log("pressing right");
+			c += 8;
+
+		LZY_DrawBegin();
+		LZY_DrawSetColor(c, c, c);
+		LZY_DrawClear();
+		LZY_DrawEnd();
 	} while (!LZY_ShouldQuit());
 
 	LZY_Log("cya");