The samples are the input to convert to u64. As we should
not modify them, mark the argument const.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 audio/audio.h  | 2 +-
 audio/mixeng.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/audio/audio.h b/audio/audio.h
index 0db3c7dd5e..f27a12298f 100644
--- a/audio/audio.h
+++ b/audio/audio.h
@@ -163,7 +163,7 @@ int wav_start_capture(AudioState *state, CaptureState *s, const char *path,
 bool audio_is_cleaning_up(void);
 void audio_cleanup(void);
 
-void audio_sample_to_uint64(void *samples, int pos,
+void audio_sample_to_uint64(const void *samples, int pos,
                             uint64_t *left, uint64_t *right);
 void audio_sample_from_uint64(void *samples, int pos,
                             uint64_t left, uint64_t right);
diff --git a/audio/mixeng.c b/audio/mixeng.c
index 739a500449..75f000e49f 100644
--- a/audio/mixeng.c
+++ b/audio/mixeng.c
@@ -338,10 +338,10 @@ f_sample *mixeng_clip_float[2] = {
     clip_natural_float_from_stereo,
 };
 
-void audio_sample_to_uint64(void *samples, int pos,
+void audio_sample_to_uint64(const void *samples, int pos,
                             uint64_t *left, uint64_t *right)
 {
-    struct st_sample *sample = samples;
+    const struct st_sample *sample = samples;
     sample += pos;
 #ifdef FLOAT_MIXENG
     error_report(
-- 
2.21.3