#include <inttypes.h>
#include "i2c_sw.h"

/* Send data byte out on bang i2c, return false if ack
 * Assumes start has been set up or a next byte
 * so  both lines are assumed low
 * **Lower byte of 'data' is sent**
 */
unsigned char i2c_send( register unsigned int data )
{
    volatile unsigned int i= 0; /* will be register */
    /* output eight bits of 'data' */
    for( ; i < 8; ++i )
    {
        /* send the data bit */
        if( data & 0x80 )
            I2C_DIR&= ~I2C_SDA;
        else
            I2C_DIR|= I2C_SDA;

        /* shift next data bit */
        data<<= 1;

        /* Toggle SCL, first high */
        I2C_DIR&= ~I2C_SCL;

#ifdef I2C_UDLY
        brief_pause( I2C_DDLY );
#endif /* I2C_UDLY */

        /* Set SCL Low */
        I2C_DIR|= I2C_SCL;
    }

    /* make sure SDA inputs */
    I2C_DIR&= ~I2C_SDA;

    /* Set  SCL High */
    I2C_DIR&= ~I2C_SCL;

    /* get the ack bit, true if ack */
    uint16_t ack= !( I2C_IN & I2C_SDA );

    if( ack ) /* leave SDA in last state! */
        I2C_DIR|= I2C_SDA;

    /* Set SCL Low */
    I2C_DIR|= I2C_SCL;

    return ack;
}

/* Assumes the IC2_MASTER_SCL is low */
void i2c_receive( unsigned char* buf, int count )
{
    unsigned char data;
    for( ; count--; )
    {
        data= 0;
        /* Release SDA */
        I2C_DIR&= ~I2C_SDA;

        volatile unsigned int i= 0;
        for( ; i < 8; ++i )
        {
            /* Set Clock High */
            I2C_DIR&= ~I2C_SCL;

            /* shift the bit over */
            data= data << 1;

            if( I2C_IN & I2C_SDA )
                data|= 0x01;

            /* Set Clock Low */
            I2C_DIR|= I2C_SCL;
        }
        /* put the input data byte into the buffer, inc buffer pointer */
        *buf++= data;

        /* No Ack after last byte */
        if( count )
            I2C_DIR|= I2C_SDA;

        /* Toggle SCL, first high */
        I2C_DIR&= ~I2C_SCL;

#ifdef I2C_UDLY
        brief_pause( I2C_DDLY );
#endif /* I2C_UDLY */

        /* Set SCL Low */
        I2C_DIR|= I2C_SCL;
    }
}

void i2c_start( void )
{
    /* Make sure both pins are high */
    I2C_DIR&= ~( I2C_SDA | I2C_SCL );
    /* Set output low here so'I2C Master Init' is not needed */
    I2C_OUT&= ~( I2C_SDA | I2C_SCL );

    /* Set SDALow, pause in case both pins were not high */
    brief_pause( I2C_SDLY );
    I2C_DIR|= I2C_SDA;

    /* Set SCL Low */
    brief_pause( I2C_SDLY );
    I2C_DIR|= I2C_SCL;
}

/* Assumes SCL is low */
void i2c_stop( void )
{
    /* make sure SDA is low */
    I2C_DIR|= I2C_SDA;

    /* SCL to high, pause in case SDA was high */
    brief_pause( I2C_SDLY );
    I2C_DIR&= ~I2C_SCL;
    /* SDA to high */
    brief_pause( I2C_SDLY );
    I2C_DIR&= ~I2C_SDA;
}