audio: replace open-coded buffer arithmetic

Replace open-coded buffer arithmetic with the new function
audio_ring_posb(). That's the position in backward direction
of a given point at a given distance.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Message-Id: <20220301191311.26695-1-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/audio/coreaudio.c b/audio/coreaudio.c
index d8a21d3e50..1fdd1d4b14 100644
--- a/audio/coreaudio.c
+++ b/audio/coreaudio.c
@@ -333,12 +333,10 @@ static OSStatus audioDeviceIOProc(
 
     len = frameCount * hw->info.bytes_per_frame;
     while (len) {
-        size_t write_len;
-        ssize_t start = ((ssize_t) hw->pos_emul) - hw->pending_emul;
-        if (start < 0) {
-            start += hw->size_emul;
-        }
-        assert(start >= 0 && start < hw->size_emul);
+        size_t write_len, start;
+
+        start = audio_ring_posb(hw->pos_emul, hw->pending_emul, hw->size_emul);
+        assert(start < hw->size_emul);
 
         write_len = MIN(MIN(hw->pending_emul, len),
                         hw->size_emul - start);