Fix wrong offset calculation in snd_pcm_{read|write}_mmap()

The offset used in snd_pcm_{read|write}_mmap() is not the linear offset
but the offset in a ring buffer.  It has to be rounded.

diff --git a/src/pcm/pcm_mmap.c b/src/pcm/pcm_mmap.c
index d07a0806898eddc4bfe8e423c4bce9bc519b4183..4621fe6f0955832d0f057ebe80d015a7483f4cc6 100644 (file)
--- a/src/pcm/pcm_mmap.c
+++ b/src/pcm/pcm_mmap.c
@@ -575,7 +575,7 @@ snd_pcm_sframes_t snd_pcm_write_mmap(snd_pcm_t *pcm, snd_pcm_uframes_t offset,
                if (err < 0)
                        break;
                xfer += frames;
-               offset += frames;
+               offset = (offset + frames) % pcm->buffer_size;
        }
        if (xfer > 0)
                return xfer;
@@ -625,7 +625,7 @@ snd_pcm_sframes_t snd_pcm_read_mmap(snd_pcm_t *pcm, snd_pcm_uframes_t offset,
                if (err < 0)
                        break;
                xfer += frames;
-               offset += frames;
+               offset = (offset + frames) % pcm->buffer_size;
        }
        if (xfer > 0)
                return xfer;