src/audio/arts/SDL_artsaudio.c
changeset 0 74212992fb08
child 252 e8157fcb3114
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/audio/arts/SDL_artsaudio.c	Thu Apr 26 16:45:43 2001 +0000
@@ -0,0 +1,247 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
+
+    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 library 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
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+    Sam Lantinga
+    slouken@devolution.com
+*/
+
+#ifdef SAVE_RCSID
+static char rcsid =
+ "@(#) $Id$";
+#endif
+
+/* Allow access to a raw mixing buffer */
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include "SDL_audio.h"
+#include "SDL_error.h"
+#include "SDL_audiomem.h"
+#include "SDL_audio_c.h"
+#include "SDL_timer.h"
+#include "SDL_audiodev_c.h"
+#include "SDL_artsaudio.h"
+
+/* The tag name used by artsc audio */
+#define ARTSC_DRIVER_NAME         "artsc"
+
+/* Audio driver functions */
+static int ARTSC_OpenAudio(_THIS, SDL_AudioSpec *spec);
+static void ARTSC_WaitAudio(_THIS);
+static void ARTSC_PlayAudio(_THIS);
+static Uint8 *ARTSC_GetAudioBuf(_THIS);
+static void ARTSC_CloseAudio(_THIS);
+
+/* Audio driver bootstrap functions */
+
+static int Audio_Available(void)
+{
+	if(arts_init())
+		return 0;
+	else
+		return 1;
+}
+
+static void Audio_DeleteDevice(SDL_AudioDevice *device)
+{
+	free(device->hidden);
+	free(device);
+}
+
+static SDL_AudioDevice *Audio_CreateDevice(int devindex)
+{
+	SDL_AudioDevice *this;
+
+	/* Initialize all variables that we clean on shutdown */
+	this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
+	if ( this ) {
+		memset(this, 0, (sizeof *this));
+		this->hidden = (struct SDL_PrivateAudioData *)
+				malloc((sizeof *this->hidden));
+	}
+	if ( (this == NULL) || (this->hidden == NULL) ) {
+		SDL_OutOfMemory();
+		if ( this ) {
+			free(this);
+		}
+		return(0);
+	}
+	memset(this->hidden, 0, (sizeof *this->hidden));
+	stream = 0;
+
+	/* Set the function pointers */
+	this->OpenAudio = ARTSC_OpenAudio;
+	this->WaitAudio = ARTSC_WaitAudio;
+	this->PlayAudio = ARTSC_PlayAudio;
+	this->GetAudioBuf = ARTSC_GetAudioBuf;
+	this->CloseAudio = ARTSC_CloseAudio;
+
+	this->free = Audio_DeleteDevice;
+
+	return this;
+}
+
+AudioBootStrap ARTSC_bootstrap = {
+	ARTSC_DRIVER_NAME, "Analog Realtime Synthesizer",
+	Audio_Available, Audio_CreateDevice
+};
+
+/* This function waits until it is possible to write a full sound buffer */
+static void ARTSC_WaitAudio(_THIS)
+{
+	Sint32 ticks;
+
+	/* Check to see if the thread-parent process is still alive */
+	{ static int cnt = 0;
+		/* Note that this only works with thread implementations 
+		   that use a different process id for each thread.
+		*/
+		if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
+			if ( kill(parent, 0) < 0 ) {
+				this->enabled = 0;
+			}
+		}
+	}
+
+	/* Use timer for general audio synchronization */
+	ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
+	if ( ticks > 0 ) {
+		SDL_Delay(ticks);
+	}
+}
+
+static void ARTSC_PlayAudio(_THIS)
+{
+	int written;
+
+	/* Write the audio data */
+	written = arts_write(stream, mixbuf, mixlen);
+	
+	/* If timer synchronization is enabled, set the next write frame */
+	if ( frame_ticks ) {
+		next_frame += frame_ticks;
+	}
+
+	/* If we couldn't write, assume fatal error for now */
+	if ( written < 0 ) {
+		this->enabled = 0;
+	}
+#ifdef DEBUG_AUDIO
+	fprintf(stderr, "Wrote %d bytes of audio data\n", written);
+#endif
+}
+
+static Uint8 *ARTSC_GetAudioBuf(_THIS)
+{
+	return(mixbuf);
+}
+
+static void ARTSC_CloseAudio(_THIS)
+{
+	if ( mixbuf != NULL ) {
+		SDL_FreeAudioMem(mixbuf);
+		mixbuf = NULL;
+	}
+	if ( stream ) {
+		arts_close_stream(stream);
+		stream = 0;
+	}
+}
+
+static int ARTSC_OpenAudio(_THIS, SDL_AudioSpec *spec)
+{
+	int bits, frag_spec;
+	Uint16 test_format, format;
+
+	/* Reset the timer synchronization flag */
+	frame_ticks = 0.0;
+
+	mixbuf = NULL;
+
+	/* Try for a closest match on audio format */
+	format = 0;
+	bits = 0;
+	for ( test_format = SDL_FirstAudioFormat(spec->format);
+						! format && test_format; ) {
+#ifdef DEBUG_AUDIO
+		fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
+#endif
+		switch ( test_format ) {
+			case AUDIO_U8:
+				bits = 8;
+				format = 1;
+				break;
+			case AUDIO_S16LSB:
+				bits = 16;
+				format = 1;
+				break;
+			default:
+				format = 0;
+				break;
+		}
+		if ( ! format ) {
+			test_format = SDL_NextAudioFormat();
+		}
+	}
+	if ( format == 0 ) {
+		SDL_SetError("Couldn't find any hardware audio formats");
+		return(-1);
+	}
+	spec->format = test_format;
+
+	stream = arts_play_stream(spec->freq, bits, spec->channels, "SDL");
+
+	/* Calculate the final parameters for this audio specification */
+	SDL_CalculateAudioSpec(spec);
+
+	/* Determine the power of two of the fragment size */
+	for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
+	if ( (0x01<<frag_spec) != spec->size ) {
+		SDL_SetError("Fragment size must be a power of two");
+		return(-1);
+	}
+	frag_spec |= 0x00020000;	/* two fragments, for low latency */
+
+#ifdef ARTS_P_PACKET_SETTINGS
+	arts_stream_set(stream, ARTS_P_PACKET_SETTINGS, frag_spec);
+#else
+	arts_stream_set(stream, ARTS_P_PACKET_SIZE, frag_spec&0xffff);
+	arts_stream_set(stream, ARTS_P_PACKET_COUNT, frag_spec>>16);
+#endif
+	spec->size = arts_stream_get(stream, ARTS_P_PACKET_SIZE);
+
+	/* Allocate mixing buffer */
+	mixlen = spec->size;
+	mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
+	if ( mixbuf == NULL ) {
+		return(-1);
+	}
+	memset(mixbuf, spec->silence, spec->size);
+
+	/* Get the parent process id (we're the parent of the audio thread) */
+	parent = getpid();
+
+	/* We're ready to rock and roll. :-) */
+	return(0);
+}