Initial commit

backends/platform/dc/audio.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <common/scummsys.h>
+#include "engines/engine.h"
+#include "audio/mixer_intern.h"
+#include "dc.h"
+
+EXTERN_C void *memcpy4s(void *s1, const void *s2, unsigned int n);
+
+uint OSystem_Dreamcast::initSound()
+{
+  stop_sound();
+  do_sound_command(CMD_SET_FREQ_EXP(FREQ_22050_EXP));
+  do_sound_command(CMD_SET_STEREO(1));
+  do_sound_command(CMD_SET_BUFFER(SOUND_BUFFER_SHIFT));
+  return read_sound_int(&SOUNDSTATUS->freq);
+}
+
+void OSystem_Dreamcast::checkSound()
+{
+  int n;
+  int curr_ring_buffer_samples;
+
+  if (!_mixer)
+	return;
+
+  if (read_sound_int(&SOUNDSTATUS->mode) != MODE_PLAY)
+	start_sound();
+
+  curr_ring_buffer_samples = read_sound_int(&SOUNDSTATUS->ring_length);
+
+  n = read_sound_int(&SOUNDSTATUS->samplepos);
+
+  if ((n-=fillpos)<0)
+	n += curr_ring_buffer_samples;
+
+  n = ADJUST_BUFFER_SIZE(n-10);
+
+  if (n<100)
+	return;
+
+  _mixer->mixCallback((byte *)temp_sound_buffer,
+		      2*SAMPLES_TO_BYTES(n));
+
+  if (fillpos+n > curr_ring_buffer_samples) {
+	int r = curr_ring_buffer_samples - fillpos;
+	memcpy4s(RING_BUF+fillpos, temp_sound_buffer, SAMPLES_TO_BYTES(r));
+	fillpos = 0;
+	n -= r;
+	memcpy4s(RING_BUF, temp_sound_buffer+r, SAMPLES_TO_BYTES(n));
+  } else {
+	memcpy4s(RING_BUF+fillpos, temp_sound_buffer, SAMPLES_TO_BYTES(n));
+  }
+  if ((fillpos += n) >= curr_ring_buffer_samples)
+	fillpos = 0;
+}