Add primitive printf functionality to the USART.

1 files changed, 24 insertions, 6 deletions

diff --git a/03-refactor/src/main.c b/03-refactor/src/main.c
index 0545087..562fda9 100644
--- a/03-refactor/src/main.c
+++ b/03-refactor/src/main.c
@@ -73,21 +73,39 @@ int enable_usart1(uint32_t baud_rate)
   asm volatile(" cpsie i ");
 }
 
+void dwn() {
+  int val = 19;
+
+  while (val > 1) {
+    usart_printf(&USART2, "Value: 0x%02x\r\n", val);
+    if ((val & 1) == 0) {
+      val /= 2;
+    } else {
+      val = val * 3 + 1;
+    }
+  }
+  usart_printf(&USART2, "Value: 0x%02x\r\n", val);
+}
+
 /* Main function. This gets executed from the interrupt vector defined above. */
 int main()
 {
   /* Enable the GPIO port B. */
-
-  __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
-  gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
-  gpio_output_pin_t pin1 = set_gpio_pin_output(port_b, PIN_1);
+  // __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
+  // gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
+  // gpio_output_pin_t pin1 = set_gpio_pin_output(port_b, PIN_1);
 
   /* Enable a higher clock frequency. */
   set_system_clock_MHz(80);
 
   enable_usart2(115200);
 
-  pin_on(pin3);
-  usart_transmit_str(&USART2, "Hello, World\n");
+  // pin_on(pin3);
+  dwn();
+  usart_printf(&USART2, "Hello, %d!\r\n", -15);
   for(;;);
 }
+
+void do_thing(void(*fn)()) {
+  fn();
+}