From 76305e7e6bc5ee232201d11b7622f2d84e265e19 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Tue, 14 Jun 2005 05:37:26 +0000
Subject: [PATCH] attempt to fix choppy audio in alsa caused by non-power-of 2
 buffer size

---
 include/alsa_funcs_list.h     |  1 +
 libs/audio/targets/snd_alsa.c | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/include/alsa_funcs_list.h b/include/alsa_funcs_list.h
index ce376e6a6..4bb2921b0 100644
--- a/include/alsa_funcs_list.h
+++ b/include/alsa_funcs_list.h
@@ -45,6 +45,7 @@ QF_ALSA_NEED (snd_pcm_uframes_t, snd_pcm_hw_params_set_period_size_near, (snd_pc
 QF_ALSA_NEED (unsigned int, snd_pcm_hw_params_set_rate_near, (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int *dir))
 #else
 QF_ALSA_NEED (int, snd_pcm_hw_params_get_buffer_size, (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val))
+QF_ALSA_NEED (int, snd_pcm_hw_params_set_buffer_size, (snd_pcm_t *pcm, const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val))
 QF_ALSA_NEED (int, snd_pcm_hw_params_get_period_size, (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir))
 QF_ALSA_NEED (int, snd_pcm_hw_params_set_access, (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t access))
 QF_ALSA_NEED (int, snd_pcm_hw_params_set_period_size_near, (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir))
diff --git a/libs/audio/targets/snd_alsa.c b/libs/audio/targets/snd_alsa.c
index 47f88be78..b9327d7bf 100644
--- a/libs/audio/targets/snd_alsa.c
+++ b/libs/audio/targets/snd_alsa.c
@@ -106,6 +106,18 @@ SNDDMA_Init_Cvars (void)
 
 static int SNDDMA_GetDMAPos (void);
 
+static snd_pcm_uframes_t
+round_buffer_size (snd_pcm_uframes_t sz)
+{
+	snd_pcm_uframes_t mask = ~0;
+
+	while (sz & mask) {
+		sz &= mask;
+		mask <<= 1;
+	}
+	return sz;
+}
+
 static volatile dma_t *
 SNDDMA_Init (void)
 {
@@ -325,6 +337,15 @@ SNDDMA_Init (void)
 					qfsnd_strerror (err));
 		goto error;
 	}
+	if (buffer_size != round_buffer_size (buffer_size)) {
+		buffer_size = round_buffer_size (buffer_size);
+		err = qfsnd_pcm_hw_params_set_buffer_size (pcm, hw, &buffer_size);
+		if (0 > err) {
+			Sys_Printf ("ALSA: unable to set buffer size. %s\n",
+						qfsnd_strerror (err));
+			goto error;
+		}
+	}
 
 	sn.samples = buffer_size * sn.channels;		// mono samples in buffer
 	sn.speed = rate;