// UART communication code
//written by BRL4

#pragma regalloc-      //need this to ensure no reg variables
char uart_recv_index ;  
char uart_send_index ; 
char* uart_send_ptr ;  
char* uart_recv_ptr ;
aos_semaphore *sem_uart_xmit;	/* Semaphore for writing UART */ 
aos_semaphore *sem_uart_recv;	/* Semaphore for reading UART */
//variable set by break and <cntl-c> 
unsigned char aos_break_id;
#pragma regalloc+

/**********************************************************/
//macros to package up semaphores and hide interrupts
#define aos_puts(str) \ 
	do{               \
	aos_wait(sem_uart_xmit); \
	uart_send_index = 0; \
	uart_send_ptr = &str[0]; \
	if (str[0]>0)    \
	{       \
   		putchar(str[0]); \
   		UCSRB.5=1;  \
   		aos_wait(sem_uart_xmit); \  
 	}  ;     \
	aos_signal(sem_uart_xmit); \
	}while(0) 

 #define aos_gets(str)  \
 	do{               \
	aos_wait(sem_uart_recv);\
	uart_recv_index=0; UCSRB.7=1;\
	uart_recv_ptr = str;  \
	aos_wait(sem_uart_recv);\
	aos_signal(sem_uart_recv);\
	}while(0) 	  

//macro to force entry into cmd shell 
//break resumes cmd task, and
//freezes ISRs and clocks 
//It is defined here because of the tight relationship with
//receive complete ISR
#define aos_break(id) \\ 
	do{      			\\
	aos_break_id = id;        \\
	aos_resume_task(cmd_tcb); \\
	}while(0) 
		      
/**********************************************************/ 
//define the structures and turn on the UART		
void aos_init_uart(long baud)
{
	sem_uart_xmit = (aos_semaphore *)aos_sem_create( 1 );
	sem_uart_recv = (aos_semaphore *)aos_sem_create( 1 );
   	UCSRB=0x18; // activate UART
   	//uses the clock freq set in the config dialog box
 	UBRRL= _MCU_CLOCK_FREQUENCY_ /(baud*16L) - 1L; 
 	UCSRB.7=1;
}
		
//receive ISR
//**********************************************************
//UART character-ready ISR
interrupt [USART_RXC] void uart_rec(void)
{
	char r_char;
	r_char=UDR;   //get a char
	//build the input string
	if ((r_char=='\r') || (r_char=='\n'))
	{
		//	putchar('\n');  //use putchar to aoid overwrite 
	   	uart_recv_ptr[uart_recv_index] = 0x00 ; //zero terminate  
		//UCSRB.7=0; //stop ISR after <CR>
		aos_signal(sem_uart_recv);	
	}
	else if (r_char==0x03)     //cntl-c
		aos_break(255);
	else
		uart_recv_ptr[uart_recv_index++] = r_char;
}
 
/**********************************************************/
//UART xmit-empty ISR
interrupt [USART_DRE] void uart_send(void)
{
	char t_char;
	t_char = uart_send_ptr[++uart_send_index];
	if (t_char == 0) 	
	{
		UCSRB.5=0; //kill isr 
		aos_signal(sem_uart_xmit); 
	}
	else  
	{
   		putchar(t_char);     //send the char 
   	}			
}
/**********************************************************/