Source Code for memcpy()

[smnoff]

How does one get the source code for memcpy()?

[Naresh]

smnoff wrote:

How does one get the source code for memcpy()?

google ;)

[Vladimir Oka]

smnoff wrote:

How does one get the source code for memcpy()?

By going to:

www.google.com

or, if one is slightly more informed:

www.gnu.org

or, even better still (advanced users only):

www.gnu.org/software/libc/

or, (for experts only):

by actually writing it

[Chris Dollin]

smnoff wrote:

How does one get the source code for memcpy()?

Why does one want the source code for memcpy?

[Not that there aren't reasons, but I'm curious as to what they are.]

Note that there is no "the" source code for memcpy. There will be
many sources: some cunningly optimised for a particular environment,
some written to make the intended effect clear; some written in ISO C,
some written in GNU C, some written in assembler ...

Was the Vax C runtime library written in C or Bliss or whatever?

--
Chris "the x. x member {}" Dollin
"Reaching out for mirrors hidden in the web." - Renaissance, /Running Hard/

[Suman]

smnoff wrote:

How does one get the source code for memcpy()?

<url:
http://cvs.opensolaris.org/source/xr.../util/memcpy.c
/>

[Richard Heathfield]

Suman said:

smnoff wrote:

How does one get the source code for memcpy()?

<url:
http://cvs.opensolaris.org/source/xr.../util/memcpy.c
/>

A very portable implementation.

I'd expect machine-specific implementations to box a bit more cleverly,
though - e.g. copying a word at a time rather than a byte as far as
possible, or using dedicated machine instructions where that's relevant.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)

[Tim Prince]

Richard Heathfield wrote:

Suman said:

smnoff wrote:

How does one get the source code for memcpy()?

<url:
http://cvs.opensolaris.org/source/xr.../util/memcpy.c
/>

A very portable implementation.

I'd expect machine-specific implementations to box a bit more cleverly,
though - e.g. copying a word at a time rather than a byte as far as
possible, or using dedicated machine instructions where that's relevant.

Some even check for specific CPU hardware variants, to work around
performance issues with certain instruction sequences. Implementations
for SSE surely will look for aligned runs which can be dealt with by
16-byte loads and stores.

[Suman]

Richard Heathfield wrote:

Suman said:

smnoff wrote:

How does one get the source code for memcpy()?

<url:
http://cvs.opensolaris.org/source/xr.../util/memcpy.c
/>

A very portable implementation.

I'd expect machine-specific implementations to box a bit more cleverly,
though - e.g. copying a word at a time rather than a byte as far as
possible, or using dedicated machine instructions where that's relevant.

<OT?>
<url:
http://cvs.opensolaris.org/source/xr...6/gen/memcpy.s
/>
</OT>

[pete]

Richard Heathfield wrote:

Suman said:

smnoff wrote:

How does one get the source code for memcpy()?

<url:
http://cvs.opensolaris.org/source/xr.../util/memcpy.c
/>

A very portable implementation.

I think the pointer types should be (unsigned char *) instead.

--
pete

[Richard Heathfield]

pete said:

Richard Heathfield wrote:

Suman said:

> smnoff wrote:
>> How does one get the source code for memcpy()?
>
> <url:
> http://cvs.opensolaris.org/source/xr.../util/memcpy.c
> />

A very portable implementation.

I think the pointer types should be (unsigned char *) instead.

On reflection, <aol>.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)

[Malcolm]

"Richard Heathfield" <in*****@invalid.invalid> wrote

Suman said:

smnoff wrote:

How does one get the source code for memcpy()?

<url:
http://cvs.opensolaris.org/source/xr.../util/memcpy.c
/>

A very portable implementation.

Though not strictly conforming.
Arbitrary data must be cast to unsigned char, not plain char.
--
Buy my book 12 Common Atheist Arguments (refuted)
$1.25 download or $7.20 paper, available www.lulu.com/bgy1mm

[Malcolm]

"smnoff" <rh******@hotmail.com> wrote in message

How does one get the source code for memcpy()?

The string library functions are generally pretty easy to implement with
reasonable efficiency.
memcpy() can be just a bte-copying loop, for instnace.

They are standard library functions for convenience, and because a clever
machine-specific implementation can take advantage of 32-bit copies and the
like. Sometimes the function call might even be inlined by the compiler.
--
Buy my book 12 Common Atheist Arguments (refuted)
$1.25 download or $7.20 paper, available www.lulu.com/bgy1mm