[PATCH 1/3] util/cutils: Introduce freq_to_str() to display Hertz units

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

Introduce freq_to_str() to convert frequency values in human
friendly units using the SI units for Hertz.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 include/qemu/cutils.h | 12 ++++++++++++
 util/cutils.c         | 10 ++++++++++
 2 files changed, 22 insertions(+)

diff --git a/include/qemu/cutils.h b/include/qemu/cutils.h
index eb59852dfdf..0186c846e9c 100644
--- a/include/qemu/cutils.h
+++ b/include/qemu/cutils.h
@@ -158,6 +158,18 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result);
 
 char *size_to_str(uint64_t val);
 
+/**
+ * freq_to_str:
+ * @freq_hz: frequency to stringify
+ *
+ * Return human readable string for frequency @freq_hz.
+ * Use SI units like KHz, MHz, and so forth.
+ *
+ * The caller is responsible for releasing the value returned with g_free()
+ * after use.
+ */
+char *freq_to_str(uint64_t freq_hz);
+
 /* used to print char* safely */
 #define STR_OR_NULL(str) ((str) ? (str) : "null")
 
diff --git a/util/cutils.c b/util/cutils.c
index 36ce712271f..dab837fd8b8 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -885,6 +885,16 @@ char *size_to_str(uint64_t val)
     return g_strdup_printf("%0.3g %sB", (double)val / div, suffixes[i]);
 }
 
+char *freq_to_str(uint64_t freq_hz)
+{
+    static const char *suffixes[] = { "", "K", "M", "G", "T", "P", "E" };
+    unsigned unit_index = log10(freq_hz) / 3;
+
+    return g_strdup_printf("%0.3g %sHz",
+                           freq_hz / pow(10.0, unit_index * 3.0),
+                           suffixes[unit_index]);
+}
+
 int qemu_pstrcmp0(const char **str1, const char **str2)
 {
     return g_strcmp0(*str1, *str2);
-- 
2.26.2