Sorry but I am new to the 8051, i am writing a C program which I am going to cross compile to assembly.

I want to read the bit on the serial data line.
basically i want to write;
if((bit on SDL)&0x01)

i read the 8051 manual and noticed that as part of the I2c control register there is a bit called MDI,
is it correct to write:

if((MDI)&0x01)
{
//input bit
}
else
{
//input 0
}