Howdy, Your aligning by 16 byte paragraph
On Fri, Sep 20, 2019 at 7:45 PM Quinton Cook <[email protected]> wrote: > Hello all, > > I have recently taken an academic interest in the freedos project. My > current goal is to understand how the kernel was implemented. > > While reading the kernel.asm file located > in freedos-svn/kernel/branches/jhall/kernel I have inferred that the > routine "kernel_start" is calculating the overall memory available to the > system. but I came across a snippet of code that confused me. Starting on > line 128 > it goes > > mov dx,init_end+15 > mov cl,4 > shr dx,cl > sub ax,dx > > why is 15 added to the end of the address of the symbol init_end if you > just shift the value right by 4, doesn't that just undo the addition? Is it > related to memory addresses having to be divisible by 16? Segmentation or > something like that? > > Also is that last sub calculating the amount of room needed for the kernel? > > I hope all is well and get back to me when it is convenient for you, thanks > -- > *Quinton Cook* > _______________________________________________ > Freedos-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freedos-devel >
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