RE: why use memcpy when memmove is there?

From: David Schwartz
Date: Tue Aug 14 2007 - 18:16:39 EST



> Hi, All
>
> We were looking at "[kernel]/lib/string.c"
> (http://lxr.linux.no/source/lib/string.c#L500)
>
> memcpy copies a part of memory to some other location
> but It will not work for all cases of overlapping
> blocks.(if the start of destination block falls
> between the source block)
>
> while memove copes with overlapping areas.
>
> then why is memcpy present in the sources can't we
> simply do
>
> "#define memcpy memmove" in include/linux/string.h
>
> or am I missing something?

Suppose you have two vehicles, an economy car and a semi truck. The truck
can go everyplace the car can go, and the truck can carry a bigger load. So
why would you ever use the car? Answer: The car uses less gas and you don't
always need a truck.

Think about what it takes to be able to copy one block of memory to another
location when those locations might overlap. You don't always need that.

DS


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