From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 29 Mar 2005 14:13:04 +0000 (+0000)
Subject: Generic architecture support
X-Git-Tag: v1.0.9rc3~30
X-Git-Url: https://git.alsa-project.org/?a=commitdiff_plain;h=920780491270d10f2563700e683883e1be683541;p=alsa-lib.git

Generic architecture support

Support dmix on generic architectures without atomic operations but
using a semaphore to avoid concurrent accesses.  This is less effective
than atomic operations but should work on every system.
---

diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
index 06e82159..290459dd 100644
--- a/src/pcm/pcm_dmix.c
+++ b/src/pcm/pcm_dmix.c
@@ -228,8 +228,15 @@ static void snd_pcm_dmix_sync_area(snd_pcm_t *pcm, snd_pcm_uframes_t size)
 		transfer = appl_ptr + size > pcm->buffer_size ? pcm->buffer_size - appl_ptr : size;
 		if (slave_appl_ptr + transfer > dmix->shmptr->s.buffer_size)
 			transfer = dmix->shmptr->s.buffer_size - slave_appl_ptr;
-		if (transfer)
+		if (transfer) {
+#ifdef NO_CONCURRENT_ACCESS
+			snd_pcm_direct_semaphore_down(dmix, DIRECT_IPC_SEM_CLIENT);
+#endif
 			mix_areas(dmix, src_areas, dst_areas, appl_ptr, slave_appl_ptr, transfer);
+#ifdef NO_CONCURRENT_ACCESS
+			snd_pcm_direct_semaphore_up(dmix, DIRECT_IPC_SEM_CLIENT);
+#endif
+		}
 		if (transfer >= size)
 			return;
 		size -= transfer;
diff --git a/src/pcm/pcm_dmix_generic.c b/src/pcm/pcm_dmix_generic.c
index 4ce77598..dfd327fb 100644
--- a/src/pcm/pcm_dmix_generic.c
+++ b/src/pcm/pcm_dmix_generic.c
@@ -1,4 +1,5 @@
-#if defined(__i386__) || defined(__x86_64__)
+#if 0
+//#if defined(__i386__) || defined(__x86_64__)
 #define LOCK_PREFIX "lock ; "
 #define ARCH_ADD(p,a)					\
 	__asm__ __volatile__(LOCK_PREFIX "addl %1,%0"	\
@@ -36,12 +37,14 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 #define ARCH_CMPXCHG(ptr,o,n)\
 	((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 					(unsigned long)(n),sizeof(*(ptr))))
+#define IS_CONCURRENT	1	/* check race */
 #endif
 
 #ifndef ARCH_ADD
-#warning Please, define atomic ADD and CMPXCHG for your architecture...
 #define ARCH_ADD(p,a) (*(p) += (a))
 #define ARCH_CMPXCHG(p,a,b) (*(p)) /* fake */
+#define NO_CONCURRENT_ACCESS	/* use semaphore to avoid race */
+#define IS_CONCURRENT	0	/* no race check */
 #endif
 
 static void mix_areas1(unsigned int size,
@@ -69,7 +72,7 @@ static void mix_areas1(unsigned int size,
 			else
 				sample = old_sample;
 			*dst = sample;
-		} while (*sum != old_sample);
+		} while (IS_CONCURRENT && *sum != old_sample);
 		if (!--size)
 			return;
 		src += src_step;
@@ -103,7 +106,7 @@ static void mix_areas2(unsigned int size,
 			else
 				sample = old_sample * 256;
 			*dst = sample;
-		} while (*sum != old_sample);
+		} while (IS_CONCURRENT && *sum != old_sample);
 		if (!--size)
 			return;
 		src += src_step;