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/* -*- c++ -*- */
/* $Id: i2c.c 395 2011-07-17 22:02:55Z mueller $ */
/*-----------------------------------------------------------------------------
 * I2C read/write functions for FX2
 *-----------------------------------------------------------------------------
 * Code taken from USRP2 firmware (GNU Radio Project), version 3.0.2,
 * Copyright 2003 Free Software Foundation, Inc.
 *-----------------------------------------------------------------------------
 * This code is part of usbjtag. usbjtag 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. usbjtag 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 General Public License for more details.  You should have received a
 * copy of the GNU General Public License along with this program in the file
 * COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin
 * St, Fifth Floor, Boston, MA  02110-1301  USA
 *-----------------------------------------------------------------------------
 */
 
#include "i2c.h"
#include "fx2regs.h"
#include <string.h>
 
 
// issue a stop bus cycle and wait for completion
 
 
// returns non-zero if successful, else 0
unsigned char
i2c_read (unsigned char addr, xdata unsigned char *buf, unsigned char len)
{
  volatile unsigned char	junk;
 
  if (len == 0)			// reading zero bytes always works
    return 1;
 
  while (I2CS & bmSTOP)		// wait for stop to clear
    ;
 
  I2CS = bmSTART;
  I2DAT = (addr << 1) | 1;	// write address and direction (1's the read bit)
 
  while ((I2CS & bmDONE) == 0)
    ;
 
  if ((I2CS & bmBERR) || (I2CS & bmACK) == 0)	// no device answered...
    goto fail;
 
  if (len == 1)
    I2CS |= bmLASTRD;		
 
  junk = I2DAT;			// trigger the first read cycle
 
  while (--len != 0){
    while ((I2CS & bmDONE) == 0)
      ;
 
    if (I2CS & bmBERR)
      goto fail;
 
    if (len == 1)
      I2CS |= bmLASTRD;
 
    *buf++ = I2DAT;		// get data, trigger another read
  }
 
  // wait for final byte
 
  while ((I2CS & bmDONE) == 0)
    ;
 
  if (I2CS & bmBERR)
    goto fail;
 
  I2CS |= bmSTOP;
  *buf = I2DAT;
 
  return 1;
 
 fail:
  I2CS |= bmSTOP;
  return 0;
}
 
 
 
// returns non-zero if successful, else 0
unsigned char
i2c_write (unsigned char addr, xdata const unsigned char *buf, unsigned char len)
{
  while (I2CS & bmSTOP)		// wait for stop to clear
    ;
 
  I2CS = bmSTART;
  I2DAT = (addr << 1) | 0;	// write address and direction (0's the write bit)
 
  while ((I2CS & bmDONE) == 0)
    ;
 
  if ((I2CS & bmBERR) || (I2CS & bmACK) == 0)	// no device answered...
    goto fail;
 
  while (len > 0){
    I2DAT = *buf++;
    len--;
 
    while ((I2CS & bmDONE) == 0)
      ;
 
    if ((I2CS & bmBERR) || (I2CS & bmACK) == 0)	// no device answered...
      goto fail;
  }
 
  I2CS |= bmSTOP;
  return 1;
 
 fail:
  I2CS |= bmSTOP;
  return 0;
}