#include "stm32f10x.h"
#include "serial.h"

/* Private variables ---------------------------------------------------------*/
unsigned char buffer_rx[64];
unsigned char buffer_rx_len;
unsigned char serial_enable;

/* unbuffered USART write */
void serial_putchar (unsigned char c)
{
	while (!(USART1->SR & USART_FLAG_TXE));

	USART_SendData (USART1, c);
}

void serial_send (char *s)
{
	while (*s)
		serial_putchar (*s ++);
}

void serial_send_len (char *s, unsigned short l)
{
	unsigned short i;
	for (i = 0; i < l; i ++)
		serial_putchar (s[i]);
}

unsigned char serial_available ()
{
	return buffer_rx_len ? 1 : 0;
}

unsigned char serial_getchar ()
{
	if (buffer_rx_len > 0)
		return buffer_rx[-- buffer_rx_len];

	return 0;
}

/**
  * @brief  This function handles USART1 global interrupt request.
  * @param  None
  * @retval None
  */
void USART1_IRQHandler (void)
{
	if (USART_GetITStatus (USART1, USART_IT_RXNE) != RESET) {
		/* Read one byte from the receive data register */
		if (buffer_rx_len < sizeof (buffer_rx))
			buffer_rx[buffer_rx_len ++] = USART_ReceiveData (USART1);
	}
}

/**
 * @brief Configure the USART interface
 * @param baudrate Assign baudrate
 * @retval None
 */
static void usart_conf (unsigned short baudrate)
{
	USART_InitTypeDef usart;

	/* USART1 configured as follow:
	      - BaudRate = 115200 baud
	      - Word Length = 8 Bits
	      - One Stop Bit
	      - No parity
	      - Hardware flow control disabled (RTS and CTS signals)
	      - Receive and transmit enabled
	*/

	usart.USART_BaudRate = baudrate;
	usart.USART_WordLength = USART_WordLength_8b;
	usart.USART_StopBits = USART_StopBits_1;
	usart.USART_Parity = USART_Parity_No;
	usart.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	usart.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

	USART_Init (USART1, &usart);

	/* Enable USARTy Receive and Transmit interrupts */
	USART_ITConfig (USART1, USART_IT_RXNE, ENABLE);

	USART_Cmd (USART1, ENABLE);

	buffer_rx_len = 0;
}

/**
 * @brief Configure the used I/O ports pin
 * @param None
 * @retval None
 */
static void gpio_conf (void)
{
	/*GPIO_InitTypeDef *gpio = (GPIO_InitTypeDef *) mem_alloc (sizeof (GPIO_InitTypeDef));

	if (!gpio)
		return;*/

	NVIC_InitTypeDef NVIC_InitStructure;

	/* Configure the NVIC Preemption Priority Bits */
	NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

	/* Enable the USARTy Interrupt */
	NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);


	GPIO_InitTypeDef gpio;

	/* Configure USART Rx as input floating */
	gpio.GPIO_Pin = GPIO_Pin_10;
	gpio.GPIO_Mode = GPIO_Mode_IPU;

	GPIO_Init (GPIOA, &gpio);

	/* Configure USART1 Tx as alternate function push-pull */
	gpio.GPIO_Pin = GPIO_Pin_9;
	gpio.GPIO_Speed = GPIO_Speed_50MHz;
	gpio.GPIO_Mode = GPIO_Mode_AF_PP;

	GPIO_Init (GPIOA, &gpio);
}
int serial_init ()
{
	gpio_conf ();
	usart_conf (115200);

	return 0;
}