On 05/07/2015 11:51 AM, John Snow wrote: > Instead of converting each byte one-at-a-time and then sending each byte > over the wire, use sprintf() to pre-compute all of the hex nibs into a > single buffer, then send the entire buffer all at once. > > This gives a moderate speed boost to memread() and memwrite() functions. > > Signed-off-by: John Snow <js...@redhat.com> > ---
> - qtest_send_prefix(chr);
> - qtest_send(chr, "OK 0x");
> + enc = g_malloc(2 * len + 1);
> for (i = 0; i < len; i++) {
> - qtest_sendf(chr, "%02x", data[i]);
> + sprintf(&enc[i * 2], "%02x", data[i]);
Making a function call to sprintf() has a lot of overhead. Isn't it
even faster to open-code the conversion, something like:
for (i = 0; i < len; i++) {
const char digits[] = "0123456789abcdef";
enc[i * 2] = digits[data[i] >> 4];
enc[i * 2 + 1] = digits[data[i] & 0xf];
}
enc[len * 2] = '\0';
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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