[Qemu-devel] [PATCH v5 2/3] utils: provide size_to_str()

[Peter Xu <peterx@redhat.com>]

I stole the algorithm from print_type_size(). I didn't generalize it
since that's using [KM...]iB while here we need [KM...]B to finally
be able to stands for page sizes (and even more general).

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/qemu-common.h |  1 +
 util/cutils.c         | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/qemu-common.h b/include/qemu-common.h
index d218821..d7d0448 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -145,6 +145,7 @@ void qemu_hexdump(const char *buf, FILE *fp, const char *prefix, size_t size);
 int parse_debug_env(const char *name, int max, int initial);
 
 const char *qemu_ether_ntoa(const MACAddr *mac);
+char *size_to_str(double val);
 void page_size_init(void);
 
 /* returns non-zero if dump is in progress, otherwise zero is
diff --git a/util/cutils.c b/util/cutils.c
index 50ad179..5aaf370 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -619,3 +619,29 @@ const char *qemu_ether_ntoa(const MACAddr *mac)
 
     return ret;
 }
+
+/*
+ * Sample output:
+ *
+ * 1          -> "1 B"
+ * 528        -> "0.516 KB"
+ * 4096       -> "4 KB"
+ * 2402958    -> "2.29 MB"
+ * 1073741824 -> "1 GB"
+ *
+ * Please free the buffer after use.
+ */
+char *size_to_str(double val)
+{
+    static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
+    unsigned long div;
+    int i;
+
+    frexp(val, &i);
+    i /= 10;
+    assert(i < sizeof(suffixes));
+    div = 1ULL << (i * 10);
+
+    return g_strdup_printf("%0.3g %c%s", val / div,
+                           suffixes[i], i ? "B" : "");
+}
-- 
2.7.4