/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2009 by Bertrik Sikken
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/

#include "config.h"
#include "as3525.h"
#include "dbop-as3525.h"

#define DBOP_IDLE_VALUE 0xE0FF

static int dbop_locked = 0;
static short int dbop_input_value = DBOP_IDLE_VALUE;

/* read the DBOP data pins */
static unsigned short dbop_read_input(void)
{
unsigned int dbop_ctrl_old = DBOP_CTRL;
unsigned int dbop_timpol23_old = DBOP_TIMPOL_23;
unsigned short value;

/* make sure that the DBOP FIFO is empty */
while ((DBOP_STAT & (1<<10)) == 0);

/* write DBOP_DOUT to pre-charge DBOP data lines with a high level */
DBOP_TIMPOL_23 = 0xe167006e; /* no strobe towards lcd */

if (dbop_locked <= 0)
{ /* can't write to dbop while updating */
DBOP_CTRL = (1 << 16) | /* enw=1 (enable write) */
(1 << 12); /* ow=1 (16-bit data width) */
DBOP_DOUT = DBOP_IDLE_VALUE; /* all pins high */
while ((DBOP_STAT & (1<<10)) == 0);
}

/* perform a DBOP read */
DBOP_CTRL = (1 << 15) | /* strd=1 (start read) */
(1 << 12) | /* ow=1 (16-bit data width) */
(31 << 0); /* rs_t=31 (read DBOP at end of cycle) */
while ((DBOP_STAT & (1<<16)) == 0);
value = DBOP_DIN;

/* restore previous values */
DBOP_TIMPOL_23 = dbop_timpol23_old;
DBOP_CTRL = dbop_ctrl_old;

if (dbop_locked > 0)
{ /* if we were blocked, use cached data partly */
int old_value = value;
value = dbop_input_value & ~(1<<14|1<<13);
value |= old_value & (1<<14|1<<13);
}
return value;
}

/* get the DBOP input value, either directly or cached if DBOP is busy */
unsigned short int dbop_input(void)
{
return (dbop_input_value = dbop_read_input());
}

/* increase dbop lock count, if not locked yet a DBOP input sample is taken */
void dbop_lock(void)
{
dbop_input();
dbop_locked++;
}

/* decrease dbop lock count */
void dbop_unlock(void)
{
dbop_locked--;
}