[LCP]stdio.h reference

[Santosh.Kawade at eyield.com]

The reason for aligning data w.r.t at boundaries is related to architecture of
the microprocessor. The microprocessor fetches data in terms of WORD size  (same
 as the width of the data bus ).
For e.g a 32 bit machine can fetch 32 bits of data from memory in one machine
cycle. If the data is not aligned at WORD boundaries it will have to generate
two fetches to access the data. Hence it doubles the fetch time. 

For e.g an int i is stored in memory at location 0X0032. Suppose it takes 4
bytes (32 bit ) of storage. The microprocessor will fetch data in terms at WORD
boundaries ( multiples of 32 ). If it is aligned it will fetch it in one go, but
suppose if it soted at 0X0020 there will be 2 machine cycles to fetch this data
one at 0X0000 and 0X0032.




____________________Reply Separator____________________
Subject:    Re: [LCP]stdio.h reference
Author: linuxcprogramming at lists.linux.org.au
Date:       1/7/02 9:06 PM

This is more of a conceptual question.
We know that multibyte data must be aligned on a
natural boundary.That is four byte dta on a four byte
boundary and two byte data on two byte boundary and so
forth.But what is the reason behind this.CAn anyone
please explain.What will be the problem if the data is
not aligned???



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