Some of the C library string functions have an unknown provenance.
Reimplement all such functions to avoid potential licensing
uncertainty.

Remove the inline-assembler versions of strlen(), memswap(), and
strncmp(); these save a minimal amount of space (around 40 bytes in
total) and are not performance-critical.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Make memswap() behave correctly if called with a length of zero.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Typical saving is 5-20 bytes in each file using strlen().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Typical saving is 20-30 bytes in each file using strncmp().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Typical saving is 15-20 bytes in each file using memmove().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Suggested-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

The "rep" prefix can be used with an iteration count of zero, which
allows the variable-length memcpy() to be implemented without using
any conditional jumps.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

Currently the only supported platform for x86_64 is EFI.

Building an EFI64 gPXE requires a version of gcc that supports
__attribute__((ms_abi)).  This currently means a development build of
gcc; the feature should be present when gcc 4.4 is released.

In the meantime; you can grab a suitable gcc tree from

  git://git.etherboot.org/scm/people/mcb30/gcc/.git