diff options
| author | Richard Henderson <rth@twiddle.net> | 2013-07-30 08:20:43 -1000 |
|---|---|---|
| committer | Anthony Liguori <aliguori@us.ibm.com> | 2013-07-31 07:54:21 -0500 |
| commit | 1197cbb9eda1dc82e2fa1815ca62bc3de158353e (patch) | |
| tree | 5bc0d98905c692aba8aa93de764bb9b8114c5591 | |
| parent | e76c756fd3d3b652c6a65ebe16f2bfb25b8d025e (diff) | |
qdev: Use clz in print_size
We can compute a floor log2 value with clz rather than a division loop.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-id: 1375208443-17288-3-git-send-email-rth@twiddle.net
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
| -rw-r--r-- | hw/core/qdev-properties.c | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c index d6d10c980e..dc8ae6958c 100644 --- a/hw/core/qdev-properties.c +++ b/hw/core/qdev-properties.c @@ -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 = { |