On 9/28/20 9:50 AM, Luc Michel wrote:
> Hi Philippe,
>
> On 11:08 Sun 27 Sep , Philippe Mathieu-Daudé wrote:
>> Introduce freq_to_str() to convert frequency values in human
>> friendly units using the SI units for Hertz.
>>
>> Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
>> ---
>> 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]);
>
> You could end up going out of your 'suffixes' array if freq_hz is very
> high.
Oh, good point.
> Also, to avoid the complexity of log10/pow, maybe something like:
>
> double freq = freq_hz;
> size_t idx = 0;
>
> while (freq >= 1000.0 && idx < ARRAY_LENGTH(suffixes)) {
> freq /= 1000.0;
> idx++;
> }
KISS, I like it :)
>
> return g_strdup_printf("%0.3g %sHz", freq, suffixes[idx]);
>
> is enough?
>
I'll respin, thanks!
Phil.
