utils: provide size_to_str()

Moving the algorithm from print_type_size() into size_to_str() so that
other component can also leverage it. With that, refactor
print_type_size().

The assert() in that logic is removed though, since even UINT64_MAX
would not overflow.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1494562661-9063-3-git-send-email-peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 6 insertions, 16 deletions

diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 94ac8211d1..53c2175d81 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -211,10 +211,8 @@ static void print_type_size(Visitor *v, const char *name, uint64_t *obj,
                             Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
-    static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
-    uint64_t div, val;
-    char *out;
-    int i;
+    uint64_t val;
+    char *out, *psize;
 
     if (!sov->human) {
         out = g_strdup_printf("%"PRIu64, *obj);
@@ -223,19 +221,11 @@ static void print_type_size(Visitor *v, const char *name, uint64_t *obj,
     }
 
     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" : "");
+    psize = size_to_str(val);
+    out = g_strdup_printf("%"PRIu64" (%s)", val, psize);
     string_output_set(sov, out);
+
+    g_free(psize);
 }
 
 static void print_type_bool(Visitor *v, const char *name, bool *obj,