/*****************************************************************************
 *
 * Filename:
 * ---------
 *   soft_i2c.c
 *
 *
 * Description:
 * ------------
 *   Use GPIO simulate I2C interface.
 *
 * Author:
 * -------
 *   jimmy.li
 ****************************************************************************/
#define uint32
#define uint16
#define uint8
#define int32
#define int16
#define int8  

/* GPIO setting */
#define SDA_GPIO
#define SCL_GPIO 

/* set GPIO function as general output/input */
#define SET_SDA_FN_0
#define SET_SCL_FN_0  

#define SET_SDA_OUTPUT
#define SET_SDA_INPUT
#define SET_SCL_OUTPUT  

/* read SDA status */
#define GET_SDA_VALUE  

/* pull SDA/SCL high or low */
#define SEND_SDA_VALUE(x)
#define PULL_SDA_LOW
#define PULL_SDA_HIGH
#define PULL_SCL_LOW
#define PULL_SCL_HIGH  

/* delay */
#define I2C_DUMMY_DELAY  \
do{\
   uint16  i2c_dummy_cnt; \
   ; i2c_dummy_cnt!=; i2c_dummy_cnt--); \
})

/*************************************************************************
* FUNCTION
* I2C_Init
*
* DESCRIPTION
* Prepare to control I2C bus, set SCL, SDA normal GPIO mode.
*
* PARAMETERS
* None.
*
* RETURNS
* None
*
*************************************************************************/
void I2C_Init(void)
{
     /* set SCL, SDA normal GPIO mode */
     SET_SDA_FN_0;
     SET_SCL_FN_0;
}

/*************************************************************************
* FUNCTION
*     I2C_Release
*
* DESCRIPTION
*     Release I2C bus.
*
* PARAMETERS
*     None.
*
* RETURNS
*     None
*
*************************************************************************/
void I2C_Release(void)
{
     /* set SCL, SDA high */
     PULL_SCL_HIGH;
     PULL_SDA_HIGH;
}

/*************************************************************************
* FUNCTION
*     I2C_Start
*
* DESCRIPTION
*     Initiate a START condition.
*     A High to Low transition on the SDA line while SCL is High defines a START condition.
*
* SCL --- ---
*            |___
* SDA ---
*        |___ ___
*
* PARAMETERS
*     None.
*
* RETURNS
*     None
*
*************************************************************************/
void I2C_Start(void)
{
     SET_SCL_OUTPUT;
     SET_SDA_OUTPUT;

     PULL_SCL_HIGH;
     PULL_SDA_HIGH;
     I2C_DUMMY_DELAY;

     PULL_SDA_LOW;
     I2C_DUMMY_DELAY;

     PULL_SCL_LOW;
     I2C_DUMMY_DELAY;
}

/*************************************************************************
* FUNCTION
*     I2C_Stop
*
* DESCRIPTION
*     Generate a Stop condition.
*     A Low to High transition on the SDA line while SCL is High defines a START condition.
*
* SCL     --- ---
*     ___|
* SDA         ---
*     ___ ___|
*
* PARAMETERS
*     None.
*
* RETURNS
*     None
*
*************************************************************************/
void I2C_Stop(void)
{
     SET_SCL_OUTPUT;
     SET_SDA_OUTPUT;

     PULL_SCL_LOW;
     PULL_SDA_LOW;
     I2C_DUMMY_DELAY;

     PULL_SCL_HIGH;
     I2C_DUMMY_DELAY;

     PULL_SDA_HIGH;
     I2C_DUMMY_DELAY;
}

/*************************************************************************
* FUNCTION
*     I2C_TxByte
*
* DESCRIPTION
*     Send a byte to I2C bus.
*
* PARAMETERS
*     @uint8 data  data to be send.
*
* RETURNS
*     ack received from I2C slave device.
*
*************************************************************************/
uint8 I2C_TxByte(uint8 data)
{
     int8 i, ack;
     SET_SCL_OUTPUT;
     SET_SDA_OUTPUT;

     // send 8bits data, MSB first
     ; --i>=; ){
          if((data>>i)& 0x01)
               PULL_SDA_HIGH;
          else
               PULL_SDA_LOW;
          I2C_DUMMY_DELAY;
          PULL_SCL_HIGH;
          I2C_DUMMY_DELAY;
          PULL_SCL_LOW;
          I2C_DUMMY_DELAY;
    }

     // receive ack
     SET_SDA_INPUT;

     PULL_SCL_HIGH;
     I2C_DUMMY_DELAY;
     ack = GET_SDA_VALUE; // read ack when HIGH period of the SCL
     PULL_SCL_LOW;

     SET_SDA_OUTPUT;
     return ack;
}

/*************************************************************************
* FUNCTION
*     I2C_RxByte
*
* DESCRIPTION
*     Receive a byte from I2C bus.
*
* PARAMETERS
*     @uint8 *data  store received data.
*     @uint8 ack  ack send to I2C slave device after receive a byte.
*                        ACK -- 0
*                        NACK -- 1
* RETURNS
*     None.
*
*************************************************************************/
void I2C_RxByte(uint8 *data, uint8 ack)
{
     int16 i;
    uint32 dataCache;
    dataCache = ;

    SET_SDA_INPUT;

    // receive 8bits data
    ; --i>=; ){
        dataCache <<= ;
        PULL_SCL_HIGH;
        I2C_DUMMY_DELAY;
        dataCache |= GET_SDA_VALUE;
        PULL_SCL_LOW;
       I2C_DUMMY_DELAY;
    }

     SET_SDA_OUTPUT;
    // send ack
    if(ack)
         PULL_SDA_HIGH;
    else
         PULL_SDA_LOW;
    I2C_DUMMY_DELAY;
    PULL_SCL_HIGH;
    I2C_DUMMY_DELAY;
    PULL_SCL_LOW;

    *data = (uint8)dataCache;
}