/**
 * Copyright (C) 2009 Ubixum, Inc. 
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 **/


#include <fx2regs.h>
#include <fx2macros.h>
#include <serial.h>


/**
 * using the comp port implies that timer 2 will be used as
 * a baud rate generator.  (Don't use timer 2)
 **/
void
sio0_init(WORD baud_rate)
    __critical
{				// baud_rate max should be 57600 since int=2 bytes

	WORD hl;		// hl value for reload     
	BYTE mult;		// multiplier for clock speed
	DWORD tmp;		// scratch for mult/divide

	// 0 = 12mhz, 1=24mhz, 2=48mhz    
	mult = CPUFREQ == CLK_12M ? 1 : CPUFREQ == CLK_24M ? 2 : 4;	// since only 3 clock speeds, fast switch instead of doing 2^clock speed pow(2,clkspd)

	// set the clock rate
	// use clock 2
	RCLK = 1;
	TCLK = 1;

//    RCAP2H:L = 0xFFFF - CLKOUT / 32 x baud_rate

	// in order to round to nearest value..
	// tmp * 2 // double
	// tmp / rate // do the divide
	// tmp + 1 // add one (which is like adding 1/2)
	// tmp / 2 // back to original rounded 
	tmp = mult * 375000L * 2;
	tmp /= baud_rate;
	tmp += 1;
	tmp /= 2;

	hl = 0xFFFF - (WORD) tmp;

	RCAP2H = MSB(hl);
	// seems that the 24/48mhz calculations are always one less than suggested values    
	// trm table 14-16
	RCAP2L = LSB(hl) + (mult > 0 ? 1 : 0);
	TR2 = 1;		// start the timer

	// set up the serial port       
	SM0 = 0;
	SM1 = 1;		// serial mode 1 (asyncronous)   
	SM2 = 0;		// has to do with receiving
	REN = 1;		// to enable receiving
	PCON |= 0x80;		// SET SMOD0, baud rate doubler
	TI = 1;			// we send initial byte

}

char
getchar()
{
	char c;
	while (!RI);
	c = SBUF0;
	RI = 0;
	return c;
}

void
_transchar(char c)
{
	while (!TI);		// wait for TI=1 
	TI = 0;
	SBUF0 = c;
}

void
putchar(char c)
{
	if (c == '\n')
		_transchar('\r');	// transmit \r\n
	_transchar(c);
	if (c == '\r')
		_transchar('\n');	// transmit \r\n
}