> A downward-growing stack is more intuitive. To access items on a downward-growing stack, you use positive offsets; for instance, sp+0x10 could be the second stack-passed argument to a function. For an upward-growing stack, you have to use negative offsets.
Why would one use negative offsets with the stack pointer instead of positive offsets with the base pointer?
Using the stack pointer, I can never dynamically push something onto the stack without changing the offsets.
Re:The x86 architecture is the weirdo, part 2
by GPerson on Friday April 22, 2022 @08:53AM
(#31121010)
“ A downward-growing stack is more intuitive. To access items on a downward-growing stack, you use positive offsets; for instance, sp+0x10 could be the second stack-passed argument to a function. For an upward-growing stack, you have to use negative offsets.”
I would expect you to use negative offsets to access the previous elements.
A downward-growing stack is more intuitive. To access items on a downward-growing stack, you use positive offsets; for instance, sp+0x10 could be the second stack-passed argument to a function. For an upward-growing stack, you have to use negative offsets.
> Hard disagree, big-endian is right and little-endian is wrong.
Little-endian is more natural. With little-endian numbers, the byte b at offset n has value b*256**n; with big-endian numbers, the byte b at offset n has value b*256**(l-n-1).
> And remember that network byte order is big-endian.
That's mostly by historical accident; the architectures originally used to implement the network protocols we use nowadays were big-endian. It makes sense in some situations to have on-wire numbers be big-endian, especially network addresses, since it allows the hardware to decide before the whole number arrives; that is less relevant nowadays because not only networks are much faster, but also it's more common to read the whole header to a buffer before making these decisions.