Joerg Sonnenberger wrote:
On Mon, Nov 03, 2008 at 11:49:50PM +0100, Christoph Mallon wrote:
You may want to make cmd[] static and/or const, so the compiler really
just puts the bytes in the data section instead of generating code,
which pretty much is the same as the assignments you just removed.
I didn't make it const originally as I am not sure if the USB stack will
never modify the buffer.
GCC generates 31 movb instructions to initialise the array on entry of
the function. Every movb is 5 Bytes long (opcode + mod r/m + sib +
offset + immediate). 31 * 5 = 155 Bytes. It is only sensible to use
static initialisation for a local array, which contains lots of zeroes,
if it can be made static or const (GCC is clever enough to turn a const
array into a static one). Yes, GCC could be more clever and use movl
instead of movb, but it isn't.
Christoph
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
