From a063c943dc918684d11ab33cb9bf217d75989f3d Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Sat, 30 Sep 2023 12:31:45 -0400
Subject: [PATCH] pulseaudio: Use pa_stream_begin_write to avoid an extra
buffer copy.
---
src/audio/pulseaudio/SDL_pulseaudio.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/src/audio/pulseaudio/SDL_pulseaudio.c b/src/audio/pulseaudio/SDL_pulseaudio.c
index d8246460104b..4d9c8cd072c3 100644
--- a/src/audio/pulseaudio/SDL_pulseaudio.c
+++ b/src/audio/pulseaudio/SDL_pulseaudio.c
@@ -104,6 +104,7 @@ static size_t (*PULSEAUDIO_pa_stream_writable_size)(const pa_stream *);
static size_t (*PULSEAUDIO_pa_stream_readable_size)(const pa_stream *);
static int (*PULSEAUDIO_pa_stream_write)(pa_stream *, const void *, size_t,
pa_free_cb_t, int64_t, pa_seek_mode_t);
+static int (*PULSEAUDIO_pa_stream_begin_write)(pa_stream *, void **, size_t *);
static pa_operation *(*PULSEAUDIO_pa_stream_drain)(pa_stream *,
pa_stream_success_cb_t, void *);
static int (*PULSEAUDIO_pa_stream_peek)(pa_stream *, const void **, size_t *);
@@ -216,6 +217,7 @@ static int load_pulseaudio_syms(void)
SDL_PULSEAUDIO_SYM(pa_stream_get_state);
SDL_PULSEAUDIO_SYM(pa_stream_writable_size);
SDL_PULSEAUDIO_SYM(pa_stream_readable_size);
+ SDL_PULSEAUDIO_SYM(pa_stream_begin_write);
SDL_PULSEAUDIO_SYM(pa_stream_write);
SDL_PULSEAUDIO_SYM(pa_stream_drain);
SDL_PULSEAUDIO_SYM(pa_stream_disconnect);
@@ -441,7 +443,16 @@ static int PULSEAUDIO_PlayDevice(SDL_AudioDevice *device, const Uint8 *buffer, i
static Uint8 *PULSEAUDIO_GetDeviceBuf(SDL_AudioDevice *device, int *buffer_size)
{
struct SDL_PrivateAudioData *h = device->hidden;
- *buffer_size = SDL_min(*buffer_size, h->bytes_requested);
+ const size_t reqsize = (size_t) SDL_min(*buffer_size, h->bytes_requested);
+ size_t nbytes = reqsize;
+ void *data = NULL;
+ if (PULSEAUDIO_pa_stream_begin_write(h->stream, &data, &nbytes) == 0) {
+ *buffer_size = (int) nbytes;
+ return (Uint8 *) data;
+ }
+
+ // don't know why this would fail, but we'll fall back just in case.
+ *buffer_size = (int) reqsize;
return device->hidden->mixbuf;
}