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control: add snd_ctl_elem_id_compare_numid() function

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Idea for the function prototype by Takashi Sakamoto.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2021-03-23 17:43:30 +01:00
parent 6f4b96ecc9
commit 83e4c1ab77
2 changed files with 27 additions and 0 deletions
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26
src/control/control.c
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@ -1819,6 +1819,32 @@ void snd_ctl_elem_id_copy(snd_ctl_elem_id_t *dst, const snd_ctl_elem_id_t *src)
*dst = *src;
}
/**
* \brief compare one #snd_ctl_elem_id_t to another using numid
* \param id1 pointer to first id
* \param id2 pointer to second id
* \retval zero when values are identical, other value on a difference (like strcmp)
*
* This comparison ignores the set of fields part.
*
* The return value can be used for sorting like qsort(). It gives persistent
* results.
*/
int snd_ctl_elem_id_compare_numid(const snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2)
{
int64_t d;
assert(id1 && id2);
d = (int64_t)id1->numid - (int64_t)id2->numid;
if (d & ((int64_t)INT_MAX + 1)) { /* fast path */
if (d > INT_MAX)
d = INT_MAX;
else if (d < INT_MIN)
d = INT_MIN;
}
return d;
}
/**
* \brief compare one #snd_ctl_elem_id_t to another
* \param id1 pointer to first id