uart: add dedicated FPS for TX

include/nvboard.h

@@ -9,6 +9,7 @@
 #include <SDL_image.h>
 
 void set_redraw();
+uint64_t nvboard_get_time();
 
 void init_render(SDL_Renderer *renderer);
 SDL_Texture* load_pic_texture(SDL_Renderer *renderer, std::string path);

src/nvboard.cpp

@@ -2,25 +2,10 @@
 #include <keyboard.h>
 #include <vga.h>
 #include <uart.h>
-#include <sys/time.h>
 #include <stdarg.h>
 
 #define FPS 60
 
-static uint64_t boot_time = 0;
-
-static uint64_t get_time_internal() {
-  struct timeval now;
-  gettimeofday(&now, NULL);
-  uint64_t us = now.tv_sec * 1000000 + now.tv_usec;
-  return us;
-}
-
-static uint64_t get_time() {
-  uint64_t now = get_time_internal();
-  return now - boot_time;
-}
-
 static SDL_Window *main_window = nullptr;
 static SDL_Renderer *main_renderer = nullptr;
 PinNode pin_array[NR_PINS];
@@ -45,7 +30,7 @@ void nvboard_update() {
   static int cpf = 1; // count per frame
   static int cnt = 0;
   if ((-- cnt) < 0) {
-    uint64_t now = get_time();
+    uint64_t now = nvboard_get_time();
     uint64_t diff = now - last;
     int cpf_new = ((uint64_t)cpf * 1000000) / ((uint64_t)diff * FPS); // adjust cpf
     cnt += cpf_new - cpf;
@@ -95,9 +80,11 @@ void nvboard_init(int vga_clk_cycle) {
     init_components(main_renderer);
     init_gui(main_renderer);
 
+    void init_nvboard_timer();
+    init_nvboard_timer();
+
     update_components(main_renderer);
 
-    boot_time = get_time_internal();
     extern void vga_set_clk_cycle(int cycle);
     vga_set_clk_cycle(vga_clk_cycle);
 }

src/timer.cpp

@@ -0,0 +1,20 @@
+#include <nvboard.h>
+#include <sys/time.h>
+
+static uint64_t boot_time = 0;
+
+static uint64_t get_time_internal() {
+  struct timeval now;
+  gettimeofday(&now, NULL);
+  uint64_t us = now.tv_sec * 1000000 + now.tv_usec;
+  return us;
+}
+
+uint64_t nvboard_get_time() {
+  uint64_t now = get_time_internal();
+  return now - boot_time;
+}
+
+void init_nvboard_timer() {
+  boot_time = get_time_internal();
+}

src/uart.cpp

@@ -1,6 +1,9 @@
 #include <nvboard.h>
 #include <uart.h>
 
+// There is no need to update TX too frequently
+#define UART_TX_FPS 5
+
 UART* uart = NULL;
 int16_t uart_divisor_cnt = 0;
 
@@ -45,8 +48,13 @@ void UART::check_tx() {
 
 void UART::update_state() {
   if (need_update_gui) {
-    need_update_gui = false;
-    update_gui();
+    static uint64_t last = 0;
+    uint64_t now = nvboard_get_time();
+    if (now - last > 1000000 / UART_TX_FPS) {
+      last = now;
+      need_update_gui = false;
+      update_gui();
+    }
   }
 }