1 files changed, 77 insertions, 11 deletions
diff --git a/libmaple/usart.h b/libmaple/usart.h
index 02fb6e0..beffa89 100644
--- a/libmaple/usart.h
+++ b/libmaple/usart.h
@@ -23,32 +23,98 @@
  * ****************************************************************************/
 
 /**
- *  @file usart.h
- *
- *  @brief USART Definitions
+ *  @brief USART definitions and prototypes
  */
 
 #ifndef _USART_H_
 #define _USART_H_
 
-#define NR_USARTS           0x3
+#include "ring_buffer.h"
 
 #ifdef __cplusplus
 extern "C"{
 #endif
 
-#define USART_MAX_BAUD      225000
+#define USART_TXE           BIT(7)
+
+/* usart device numbers  */
+enum {
+   USART1,
+   USART2,
+   USART3,
+};
+
+/* peripheral register struct  */
+typedef struct usart_port {
+    volatile uint32 SR;       // Status register
+    volatile uint32 DR;       // Data register
+    volatile uint32 BRR;      // Baud rate register
+    volatile uint32 CR1;      // Control register 1
+    volatile uint32 CR2;      // Control register 2
+    volatile uint32 CR3;      // Control register 3
+    volatile uint32 GTPR;     // Guard time and prescaler register
+} usart_port;
+
+/* usart descriptor  */
+struct usart_dev {
+   usart_port *base;
+   ring_buffer rb;
+   uint8 rx_buf[64];
+   const uint8 rcc_dev_num;
+   const uint8 nvic_dev_num;
+};
+
+extern struct usart_dev usart_dev_table[];
+
+
+/**
+ * @brief send one character on a usart
+ * @param usart_num usart to send on
+ * @param byte byte to send
+ */
+static inline void usart_putc(uint8 usart_num, uint8 byte) {
+    usart_port *port = usart_dev_table[usart_num].base;
+
+    port->DR = byte;
+
+    /* Wait for transmission to complete  */
+    while ((port->SR & USART_TXE) == 0)
+        ;
+}
+
+
+/**
+ * @brief read one character from a usart
+ * @param usart_num usart to read from
+ * @return byte read
+ */
+static inline uint8 usart_getc(uint8 usart_num) {
+    return rb_remove(&usart_dev_table[usart_num].rb);
+}
+
+
+/**
+ * @brief return the amount of data available in the rx buffer
+ * @param usart_num which usart to check
+ * @return number of bytes in the rx buffer
+ */
+static inline uint32 usart_data_available(uint8 usart_num) {
+    return rb_full_count(&usart_dev_table[usart_num].rb);
+}
+
+
+/**
+ * @brief removes the contents of the rx fifo
+ * @param usart_num which usart to reset
+ */
+static inline void usart_reset_rx(uint8 usart_num) {
+    rb_reset(&usart_dev_table[usart_num].rb);
+}
 
 void usart_init(uint8 usart_num, uint32 baud);
 void usart_disable(uint8 usart_num);
-
 void usart_putstr(uint8 usart_num, const char*);
 void usart_putudec(uint8 usart_num, uint32 val);
-void usart_putc(uint8 usart_num, uint8 ch);
-
-uint32 usart_data_available(uint8 usart_num);
-uint8 usart_getc(uint8 usart_num);
-void usart_clear_buffer(uint8 usart_num);
 
 #ifdef __cplusplus
 } // extern "C"