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authorPaolo Bonzini <pbonzini@redhat.com>2014-02-08 11:01:57 +0100
committerAndreas Färber <afaerber@suse.de>2014-02-14 21:12:05 +0100
commite41b509d68afb1f329c8558b6edfe2fcbac88e66 (patch)
tree3885701adcfc6f88b28cec652e52c8a95517887f /qapi
parent85ca1202d1227b3a816c714db6c8e19b613172c5 (diff)
downloadqemu-arm-e41b509d68afb1f329c8558b6edfe2fcbac88e66.tar.gz
qapi: Refine human printing of sizes
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 <eblake@redhat.com> Reviewed-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Andreas Färber <afaerber@suse.de>
Diffstat (limited to 'qapi')
-rw-r--r--qapi/string-output-visitor.c23
1 files changed, 12 insertions, 11 deletions
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 67a8798292..fb1d2e806d 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);
}