qemu/qapi/string-output-visitor.c
Paolo Bonzini e41b509d68 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>
2014-02-14 21:12:05 +01:00

140 lines
3.6 KiB
C

/*
* String printing Visitor
*
* Copyright Red Hat, Inc. 2012
*
* Author: Paolo Bonzini <pbonzini@redhat.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu-common.h"
#include "qapi/string-output-visitor.h"
#include "qapi/visitor-impl.h"
#include "qapi/qmp/qerror.h"
#include "qemu/host-utils.h"
#include <math.h>
struct StringOutputVisitor
{
Visitor visitor;
bool human;
char *string;
};
static void string_output_set(StringOutputVisitor *sov, char *string)
{
g_free(sov->string);
sov->string = string;
}
static void print_type_int(Visitor *v, int64_t *obj, const char *name,
Error **errp)
{
StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
char *out;
if (sov->human) {
out = g_strdup_printf("%lld (%#llx)", (long long) *obj, (long long) *obj);
} else {
out = g_strdup_printf("%lld", (long long) *obj);
}
string_output_set(sov, out);
}
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', 'P', 'E' };
uint64_t div, val;
char *out;
int i;
if (!sov->human) {
out = g_strdup_printf("%"PRIu64, *obj);
string_output_set(sov, out);
return;
}
val = *obj;
/* 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("%"PRIu64" (%0.3g %c%s)", val,
(double)val/div, suffixes[i], i ? "iB" : "");
string_output_set(sov, out);
}
static void print_type_bool(Visitor *v, bool *obj, const char *name,
Error **errp)
{
StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
string_output_set(sov, g_strdup(*obj ? "true" : "false"));
}
static void print_type_str(Visitor *v, char **obj, const char *name,
Error **errp)
{
StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
char *out;
if (sov->human) {
out = *obj ? g_strdup_printf("\"%s\"", *obj) : g_strdup("<null>");
} else {
out = g_strdup(*obj ? *obj : "");
}
string_output_set(sov, out);
}
static void print_type_number(Visitor *v, double *obj, const char *name,
Error **errp)
{
StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
string_output_set(sov, g_strdup_printf("%f", *obj));
}
char *string_output_get_string(StringOutputVisitor *sov)
{
char *string = sov->string;
sov->string = NULL;
return string;
}
Visitor *string_output_get_visitor(StringOutputVisitor *sov)
{
return &sov->visitor;
}
void string_output_visitor_cleanup(StringOutputVisitor *sov)
{
g_free(sov->string);
g_free(sov);
}
StringOutputVisitor *string_output_visitor_new(bool human)
{
StringOutputVisitor *v;
v = g_malloc0(sizeof(*v));
v->human = human;
v->visitor.type_enum = output_type_enum;
v->visitor.type_int = print_type_int;
v->visitor.type_size = print_type_size;
v->visitor.type_bool = print_type_bool;
v->visitor.type_str = print_type_str;
v->visitor.type_number = print_type_number;
return v;
}