function, pointer to an instance

Code C - [expand]
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/**
 * Set the I2C bus speed in conjunction with the clock frequency.
 * param p_twi Pointer to a TWI instance.
 * ul_speed: The desired I2C bus speed (in Hz) (ul_speed to DesiredClock)
 * ul_mck: Main clock of the device (in Hz). (ul_mck to MainClock)
 * return value PASS\Fail New speed setting is accepted\rejected
 */
uint32_t twi_set_speed(Twi *p_twi, uint32_t ul_speed, uint32_t ul_mck)
{
    uint32_t ckdiv = 0;
    uint32_t c_lh_div;
 
    if (ul_speed > I2C_FAST_MODE_SPEED) {
        return FAIL;
    }
 
    c_lh_div = ul_mck / (ul_speed * TWI_CLK_DIVIDER) - TWI_CLK_CALC_ARGU;
 
    /* cldiv must fit in 8 bits, ckdiv must fit in 3 bits */
    while ((c_lh_div > TWI_CLK_DIV_MAX) && (ckdiv < TWI_CLK_DIV_MIN)) {
        /* Increase clock divider */
        ckdiv++;
        /* Divide cldiv value */
        c_lh_div /= TWI_CLK_DIVIDER;
    }
 
    /* set clock waveform generator register */
    p_twi->TWI_CWGR =
            TWI_CWGR_CLDIV(c_lh_div) | TWI_CWGR_CHDIV(c_lh_div) |
            TWI_CWGR_CKDIV(ckdiv);
 
    return PASS;
}