[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PULL 14/14] qapi: refine human printing of sizes
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 14/14] qapi: refine human printing of sizes |
Date: |
Sat, 8 Feb 2014 11:01:57 +0100 |
This fixes several bugs or shortcomings of the previous pretty-printer.
In particular:
* use PRIu64 instead of casting to long long
* the exact value is included too
* the correct unit of measure (MiB, GiB, etc.) is used. PiB and EiB
are added too.
* due to an off-by-one error, 512*2^30 was printed as 0.500MiB rather than
512MiB. floor(log2(val)) is equal to 63 - clz(val), while the code used 64.
* The desired specification is %g rather than %f, which always uses three
decimals in the current code. However %g would switch to scientific
notation when the integer part is >= 1000 (e.g. 1000*2^30). To keep the
code simple, switch to the higher power when the integer part is >= 1000;
overflow is avoided by using frexp instead of clz.
Suggested-by: Eric Blake <address@hidden>
Reviewed-by: Igor Mammedov <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
qapi/string-output-visitor.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 67a8798..fb1d2e8 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -15,6 +15,7 @@
#include "qapi/visitor-impl.h"
#include "qapi/qmp/qerror.h"
#include "qemu/host-utils.h"
+#include <math.h>
struct StringOutputVisitor
{
@@ -47,30 +48,30 @@ static void print_type_size(Visitor *v, uint64_t *obj,
const char *name,
Error **errp)
{
StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
- static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T' };
+ static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
uint64_t div, val;
char *out;
int i;
if (!sov->human) {
- out = g_strdup_printf("%llu", (long long) *obj);
+ out = g_strdup_printf("%"PRIu64, *obj);
string_output_set(sov, out);
return;
}
val = *obj;
- /* 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;
- }
+ /* The exponent (returned in i) minus one gives us
+ * floor(log2(val * 1024 / 1000). The correction makes us
+ * switch to the higher power when the integer part is >= 1000.
+ */
+ frexp(val / (1000.0 / 1024.0), &i);
+ i = (i - 1) / 10;
+ assert(i < ARRAY_SIZE(suffixes));
div = 1ULL << (i * 10);
- out = g_strdup_printf("%0.03f%c", (double)val/div, suffixes[i]);
+ out = g_strdup_printf("%"PRIu64" (%0.3g %c%s)", val,
+ (double)val/div, suffixes[i], i ? "iB" : "");
string_output_set(sov, out);
}
--
1.8.5.3
- [Qemu-devel] [PULL 03/14] qdev: remove legacy parsers for hex8/32/64, (continued)
- [Qemu-devel] [PULL 03/14] qdev: remove legacy parsers for hex8/32/64, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 04/14] qdev: legacy properties are now read-only, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 05/14] qdev: legacy properties are just strings, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 06/14] qdev: inline qdev_prop_parse, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 08/14] qdev: use human mode in "info qtree", Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 09/14] qdev: remove most legacy printers, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 10/14] qdev: remove hex8/32/64 property types, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 11/14] block: handle "rechs" and "large" translation options, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 12/14] qdev: add enum property types to QAPI schema, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 13/14] qdev: use QAPI type names for properties, Paolo Bonzini, 2014/02/08
- [Qemu-devel] [PULL 14/14] qapi: refine human printing of sizes,
Paolo Bonzini <=
- [Qemu-devel] [PULL 07/14] qapi: add human mode to StringOutputVisitor, Paolo Bonzini, 2014/02/08
- Re: [Qemu-devel] [PULL 00/14] Cleanup qdev legacy properties, Andreas Färber, 2014/02/08