From 88f30b10db36934145be2971f18a346ac557950c Mon Sep 17 00:00:00 2001
From: Jaroslav Kysela <perex@perex.cz>
Date: Tue, 10 Nov 1998 13:26:03 +0000
Subject: [PATCH] Added pcm_loopback...

---
 src/pcm/Makefile       |   4 +-
 src/pcm/pcm_loopback.c | 125 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+), 2 deletions(-)
 create mode 100644 src/pcm/pcm_loopback.c

diff --git a/src/pcm/Makefile b/src/pcm/Makefile
index 0825c683..8bc28fbc 100644
--- a/src/pcm/Makefile
+++ b/src/pcm/Makefile
@@ -7,8 +7,8 @@ include ../../Makefile.conf
 
 TARGET=libpcm.a
 STARGET=libpcm.Sa
-OBJECTS=pcm.o
-SOBJECTS=pcm.So
+OBJECTS=pcm.o pcm_loopback.o
+SOBJECTS=pcm.So pcm_loopback.So
 TARGETS=$(TARGET) $(STARGET)
 
 .SUFFIXES: .c .s .S .o .So .a .Sa
diff --git a/src/pcm/pcm_loopback.c b/src/pcm/pcm_loopback.c
new file mode 100644
index 00000000..ca9a1272
--- /dev/null
+++ b/src/pcm/pcm_loopback.c
@@ -0,0 +1,125 @@
+/*
+ *  PCM LoopBack Interface - main file
+ *  Copyright (c) 1998 by Jaroslav Kysela <perex@jcu.cz>
+ *
+ *
+ *   This library is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Library General Public License as
+ *   published by the Free Software Foundation; either version 2 of
+ *   the License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU Library General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Library General Public
+ *   License along with this library; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include "asoundlib.h"
+
+#define SND_FILE_PCM_LB		"/proc/asound/%i/pcm%i%s"
+#define SND_PCM_LB_VERSION_MAX	SND_PROTOCOL_VERSION( 1, 0, 0 )
+ 
+typedef struct {
+  int card;
+  int device;
+  int fd;
+} snd_pcm_loopback_t;
+ 
+int snd_pcm_loopback_open( void **handle, int card, int device, int mode )
+{
+  int fd, ver;
+  char filename[32];
+  snd_pcm_loopback_t *lb;
+
+  *handle = NULL;
+  if ( card < 0 || card >= SND_CARDS ) return -EINVAL;
+  sprintf( filename, SND_FILE_PCM_LB, card, device,
+  	   mode == SND_PCM_LB_OPEN_RECORD ? "r" : "p" );
+  if ( (fd = open( filename, mode )) < 0 ) return -errno;
+  if ( ioctl( fd, SND_PCM_IOCTL_PVERSION, &ver ) < 0 ) {
+    close( fd );
+    return -errno;
+  }
+  if ( SND_PROTOCOL_UNCOMPATIBLE( ver, SND_PCM_LB_VERSION_MAX ) ) {
+    close( fd );
+    return -SND_ERROR_UNCOMPATIBLE_VERSION;
+  }
+  lb = (snd_pcm_loopback_t *)calloc( 1, sizeof( snd_pcm_loopback_t ) );
+  if ( lb == NULL ) {
+    close( fd );
+    return -ENOMEM;
+  }
+  lb -> card = card;
+  lb -> device = device;
+  lb -> fd = fd;
+  *handle = lb;
+  return 0;
+}
+
+int snd_pcm_loopback_close( void *handle )
+{
+  snd_pcm_loopback_t *lb;
+  int res;
+  
+  lb = (snd_pcm_loopback_t *)handle;
+  if ( !lb ) return -EINVAL;
+  res = close( lb -> fd ) < 0 ? -errno : 0;
+  free( lb );
+  return res;
+}
+
+int snd_pcm_loopback_file_descriptor( void *handle )
+{
+  snd_pcm_loopback_t *lb;
+  
+  lb = (snd_pcm_loopback_t *)handle;
+  if ( !lb ) return -EINVAL;
+  return lb -> fd;
+}
+
+int snd_pcm_loopback_stream_mode( void *handle, int mode )
+{
+  snd_pcm_loopback_t *lb;
+  long lmode = mode;
+  
+  lb = (snd_pcm_loopback_t *)handle;
+  if ( !lb ) return -EINVAL;
+  if ( ioctl( lb -> fd, SND_PCM_LB_IOCTL_STREAM_MODE, &lmode ) < 0 )
+    return -errno;
+  return 0;
+}
+
+int snd_pcm_loopback_format( void *handle, snd_pcm_format_t *format )
+{
+  snd_pcm_loopback_t *lb;
+  
+  lb = (snd_pcm_loopback_t *)handle;
+  if ( !lb ) return -EINVAL;
+  if ( ioctl( lb -> fd, SND_PCM_LB_IOCTL_FORMAT, format ) < 0 )
+    return -errno;
+  return 0;
+}
+
+ssize_t snd_pcm_loopback_read( void *handle, void *buffer, size_t size )
+{
+  snd_pcm_loopback_t *lb;
+  ssize_t result;
+  
+  lb = (snd_pcm_loopback_t *)handle;
+  if ( !lb ) return -EINVAL;
+  result = read( lb -> fd, buffer, size );
+  if ( result < 0 ) return -errno;
+  return result;
+}
-- 
2.47.1