Explanation required for Linux source code [setup.s]

[osdevkid]

Dear All,

I have attached a linux boot sector file [bootsect.s]

I have read the code several times, but few lines I cant able to understand, can you please help me ?

Line numbers from 172 to 174.

[Tosi]

Shifting an unsigned value left by 9 effectively multiplies it by 2^9, which is 512, the size of a sector. So it is converting a number of sectors into the size of those sectors in bytes, and adding bx, which is explained above as "bx is starting address within segment".

[Combuster]

Its a left shift by 9 bits, in other words, a multiplication by 512. In this case it looks like they are converting sectors to bytes.

[osdevkid]

Oh god, how simple it is, I cant able to get it.

Thank you very much for Tosi and Cumbuster.