Commit 1197cbb9 authored by Richard Henderson's avatar Richard Henderson Committed by Anthony Liguori
Browse files

qdev: Use clz in print_size 



We can compute a floor log2 value with clz rather than a division loop.

Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
Message-id: 1375208443-17288-3-git-send-email-rth@twiddle.net
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent e76c756f

hw/core/qdev-properties.c

+13 −7
Original line number Diff line number Diff line
@@ -1172,15 +1172,21 @@ static int parse_size(DeviceState *dev, Property *prop, const char *str) 


static int print_size(DeviceState *dev, Property *prop, char *dest, size_t len)

{

    uint64_t *ptr = qdev_get_prop_ptr(dev, prop);

    char suffixes[] = {'T', 'G', 'M', 'K', 'B'};

    int i = 0;

    uint64_t div;

    static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T' };

    uint64_t div, val = *(uint64_t *)qdev_get_prop_ptr(dev, prop);

    int i;



    for (div = 1ULL << 40; !(*ptr / div) ; div >>= 10) {

        i++;

    /* Compute floor(log2(val)).  */

    i = 64 - clz64(val);



    /* Find the power of 1024 that we'll display as the units.  */

    i /= 10;

    if (i >= ARRAY_SIZE(suffixes)) {

        i = ARRAY_SIZE(suffixes) - 1;

    }

    return snprintf(dest, len, "%0.03f%c", (double)*ptr/div, suffixes[i]);

    div = 1ULL << (i * 10);



    return snprintf(dest, len, "%0.03f%c", (double)val/div, suffixes[i]);

}



PropertyInfo qdev_prop_size = {