1 files changed, 80 insertions, 0 deletions
diff --git a/02.5-collatz/src/usart.c b/02.5-collatz/src/usart.c
new file mode 100644
index 0000000..eddfbe7
--- /dev/null
+++ b/02.5-collatz/src/usart.c
@@ -0,0 +1,80 @@
+#include "usart.h"
+#include "delay.h"
+
+void set_usart1_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src)
+{
+  rcc->ccip_r = rcc->ccip_r & (~0x03) | usart_clk_src;
+}
+
+void set_usart2_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src)
+{
+  rcc->ccip_r = rcc->ccip_r & ~(0x03 << 2) | (usart_clk_src << 2);
+}
+
+void set_usart2_clock_enabled(__IO rcc_t* rcc, bool enable)
+{
+  if (enable) {
+    rcc->apb1en1_r |= BIT(17);
+  } else {
+    rcc->apb1en1_r &= ~BIT(17);
+  }
+}
+
+void set_usart1_clock_enabled(__IO rcc_t* rcc, bool enable)
+{
+  if (enable) {
+    rcc->apb2en_r |= BIT(14);
+  } else {
+    rcc->apb2en_r &= ~BIT(14);
+  }
+}
+
+void usart_set_parity(__IO usart_t* usart, usart_parity_t parity)
+{
+  uint32_t c_r1 = usart->c_r1;
+  c_r1 &= ~(0x3 << 9);
+  c_r1 |= parity;
+  usart->c_r1 = c_r1;
+}
+
+void usart_set_enabled(__IO usart_t* usart, usart_enable_t enabled)
+{
+  uint32_t c_r1 = usart->c_r1;
+
+  if (!enabled) {
+    usart->c1_bf.ue = 0;
+  } else {
+    /* Set the rx enabled. */
+    usart->c1_bf.re = !!(enabled & USART_ENABLE_RX);
+    usart->c1_bf.te = !!(enabled & USART_ENABLE_TX);
+    usart->c1_bf.ue = 1;
+  }
+}
+
+void usart_transmit_byte(__IO usart_t* usart, uint8_t byte)
+{
+  usart->td_r = byte;
+  /* Per the manual, when bit 7 of the IS register is set, then the usart
+   * data has been sent to the shift register.
+   *
+   * This bit is cleared by writing to the TD register. */
+  while (!(usart->is_r & BIT(7)))
+    ;
+}
+
+void usart_transmit_bytes(__IO usart_t* usart, const uint8_t* bytes, uint32_t n)
+{
+  while (n --) {
+    usart_transmit_byte(usart, *(bytes ++));
+  }
+}
+
+void usart_transmit_str(__IO usart_t* usart, const char* str)
+{
+  while (*str) {
+    if (*str == '\n') {
+      usart_transmit_byte(usart, '\r');
+    }
+    usart_transmit_byte(usart, *(str ++));
+  }
+}