TCA9535: Doubt Regarding switch interface with I/O Expander.

uint32_t i2c_dataread(uint16_t addrs, uint16_t byte_val)
				{
				uint8_t addrs_count = 2, re_read_limit = 0;
				uint8_t Read_Write_Error = 0;
				uint8_t byte_count = 0;
				uint8_t re_write_limit = 0;	//For re-writing address byte
				uint32_t read_value = 0, hold_time = 0;
				uint8_t data_byte[4] = {0, 0, 0, 0}, addr_byte[2] = {0, 0};

			//addr_byte[0] =(addrs >> 8) & 0xFF;
				addr_byte[0] =(addrs >> 0) & 0xFF;

				if((addrs >= 65535) && (byte_val > 1))
				{
				Read_Write_Error = 1;
				}
        
				i2c_start(WRITE_BIT);

				for(byte_count = 1;((byte_count < addrs_count) && !Read_Write_Error); byte_count++)
				{
				//Waiting to enable the MSTPENDING bit to be set internally in status register
				//then only write possible in MSTCTL register
				while((I2C4->STAT & 0x01U) == 0)
				{
				hold_time++;
				if(hold_time > 1000)
				{
				hold_time = 0;
				break;
				}
				}
	//		PRINTF("write hold_time %d\n", hold_time);
				
				if(I2C4->STAT == 0x805U)	//Checks MASTER ready to transmitt or not
				{
				I2C4->MSTDAT = addr_byte[byte_count-1];		//Writing address bytes as msb and lsb
				I2C4->MSTCTL = 0x01U;
				}
				
				else
				{
				i2c_Stop();
				delay1ms()
				re_write_limit++;
			  byte_count = 0;
				if(re_write_limit > 4)
				{
				Read_Write_Error = 1;
				}
				i2c_start(WRITE_BIT);
				}
       			  }
				
				
        i2c_start(READ_BIT);
				hold_time = 0;
				
				for(byte_count = 1; ((byte_count < (byte_val+1)) && !Read_Write_Error); byte_count++)
				{
				//Waiting to enable the MSTPENDING bit to be set internally in status register
				//then only write possible in MSTCTL register
			  while((I2C4->STAT & 0x01U) == 0)
				{
				hold_time++;
				if(hold_time > 1000)
				{
				hold_time = 0;
				break;
				}
				}
				//		PRINTF("write hold_time %d\n", hold_time);
				if(I2C4->STAT == 0x803U)	//Checks MASTER ready to receive or not
				{
				data_byte[byte_count-1] = I2C4->MSTDAT;
				I2C4->MSTCTL = 0x01U;
				}
				else
			  {
			  i2c_Stop();
				delay1ms()
				if(re_read_limit > 4)
				{
				Read_Write_Error = 1;
				}
				re_read_limit++;
				byte_count = 0;
			//Re-send start condition with read bit if master is other than pending and receive status
				i2c_start(READ_BIT);
				}
				}
				
				i2c_Stop();
				read_value = 0;

				//(((byte_val-1)-byte_count)*8) - logic is for shifting data_byte values and retun as a complete no of  bytes readed
				//				here (bytes_val - 1) - is for 0 to 3(if 4 bytes) - no. of bytes - 1
				//				(- byte_count) - is for getting 0 when writing msb as first byte
				//				* 8 means left shifting 8 bytes from actual byte value
				for(byte_count = 0; byte_count < byte_val; byte_count++)
				{
				read_value = read_value + (data_byte[byte_count]<<(((byte_val-1)-byte_count)*8));
	//		PRINTF("0x%2x\t", data_byte[byte_count]);
				}
	//	  PRINTF("\r\n\r\n");
				return read_value;
				}