sound blaster code doesn't work yet

Author: jtsiomb

.gitattributes

@@ -1,2 +1,3 @@
 *.raw filter=lfs diff=lfs merge=lfs -text
 *.pal filter=lfs diff=lfs merge=lfs -text
+*.pcm filter=lfs diff=lfs merge=lfs -text

Makefile

@@ -1,5 +1,5 @@
 csrc = $(wildcard src/*.c) $(wildcard src/libc/*.c) $(wildcard src/test/*.c)
-ssrc = $(wildcard src/*.s) $(wildcard src/libc/*.s) $(wildcard src/boot/*.s)
+ssrc = $(wildcard src/*.s) $(wildcard src/libc/*.s) $(wildcard src/boot/*.s) $(wildcard src/test/*.s)
 Ssrc = $(wildcard src/*.S)
 obj = $(csrc:.c=.o) $(ssrc:.s=.o) $(Ssrc:.S=.o)
 dep = $(obj:.o=.d)

click-s8_mono.pcm

@@ -19,6 +19,8 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include "audio.h"
 #include "au_sb.h"
 #include "asmops.h"
+#include "intr.h"
+#include "dma.h"
 
 #define REG_MIXPORT		(base_port + 0x4)
 #define REG_MIXDATA		(base_port + 0x5)
@@ -33,20 +35,49 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #define WSTAT_BUSY		0x80
 #define RSTAT_RDY		0x80
 
-#define CMD_SET_RATE	0x41
-#define CMD_PLAY_PCM	0xa6
-#define CMD_STOP_PCM	0xd9
-#define CMD_GET_VER		0xe1
+#define CMD_RATE			0x40
+#define CMD_SB16_OUT_RATE	0x41
+#define CMD_SB16_IN_RATE	0x42
+#define CMD_GET_VER			0xe1
+
+/* start DMA playback/recording. combine with fifo/auto/input flags */
+#define CMD_START_DMA8		0xc0
+#define CMD_START_DMA16		0xb0
+#define CMD_FIFO			0x02
+#define CMD_AUTO			0x04
+#define CMD_INPUT			0x08
+
+/* immediately pause/continue */
+#define CMD_PAUSE_DMA8		0xd0
+#define CMD_CONT_DMA8		0xd4
+#define CMD_PAUSE_DMA16		0xd5
+#define CMD_CONT_DMA16		0xd6
+
+/* end the playback at the end of the current buffer */
+#define CMD_END_DMA16		0xd9
+#define CMD_END_DMA8		0xda
+
+/* transfer mode commands */
+#define CMD_MODE_SIGNED		0x10
+#define CMD_MODE_STEREO		0x20
 
 #define VER_MAJOR(x)	((x) >> 8)
 #define VER_MINOR(x)	((x) & 0xff)
 
+static void intr_handler();
+static void start_dma_transfer(uint32_t addr, int size);
 static void write_dsp(unsigned char val);
 static unsigned char read_dsp(void);
 static int get_dsp_version(void);
 static const char *sbname(int ver);
 
+extern unsigned char low_mem_buffer[];
+
 static int base_port;
+static int irq, dma_chan;
+static int sb16;
+static void *buffer;
+static int xfer_mode;
 
 int sb_detect(void)
 {
@@ -56,12 +87,17 @@ int sb_detect(void)
 		base_port = 0x200 + ((i + 1) << 4);
 		if(sb_reset_dsp() == 0) {
 			ver = get_dsp_version();
+			sb16 = VER_MAJOR(ver) >= 4;
 			printf("sb_detect: found %s (DSP v%d.%02d) at port %xh\n", sbname(ver),
 					VER_MAJOR(ver), VER_MINOR(ver), base_port);
 			return 1;
 		}
 	}
 
+	/* TODO: detect these somehow? */
+	irq = 5;
+	dma_chan = 1;
+
 	return 0;
 }
 
@@ -84,6 +120,101 @@ int sb_reset_dsp(void)
 	return -1;
 }
 
+void sb_set_output_rate(int rate)
+{
+	if(sb16) {
+		write_dsp(CMD_SB16_OUT_RATE);
+		write_dsp(rate >> 8);
+		write_dsp(rate & 0xff);
+	} else {
+		int tcon = 256 - 1000000 / rate;
+		write_dsp(CMD_RATE);
+		write_dsp(tcon);
+	}
+}
+
+void *sb_buffer(int *size)
+{
+	*size = 65536;
+	return buffer;
+}
+
+void sb_start(int rate, int nchan)
+{
+	uint32_t addr;
+	int size;
+
+	/* for now just use the are after boot2. it's only used by the second stage
+	 * loader and the VBE init code, none of which should overlap with audio playback.
+	 * It's not necessary to use low memory. We can use up to the first 16mb for this,
+	 * so if this becomes an issue, I'll make a DMA buffer allocator over 1mb.
+	 * start the buffer from the next 64k boundary.
+	 */
+	addr = ((uint32_t)low_mem_buffer + 0xffff) & 0xffff0000;
+	buffer = (void*)addr;
+
+	xfer_mode = CMD_MODE_SIGNED;
+	if(nchan > 1) {
+		xfer_mode |= CMD_MODE_STEREO;
+	}
+
+	if(!(size = audio_callback(buffer, 65536))) {
+		return;
+	}
+
+	interrupt(IRQ_TO_INTR(irq), intr_handler);
+
+	start_dma_transfer(addr, size);
+}
+
+void sb_pause(void)
+{
+	write_dsp(CMD_PAUSE_DMA8);
+}
+
+void sb_continue(void)
+{
+	write_dsp(CMD_CONT_DMA8);
+}
+
+void sb_stop(void)
+{
+	write_dsp(CMD_END_DMA8);
+}
+
+void sb_volume(int vol)
+{
+	/* TODO */
+}
+
+static void intr_handler()
+{
+	int size;
+
+	/* ask for more data */
+	if(!(size = audio_callback(buffer, 65536))) {
+		sb_stop();
+		return;
+	}
+	start_dma_transfer((uint32_t)buffer, size);
+
+	/* acknowledge the interrupt */
+	inb(REG_INTACK);
+}
+
+static void start_dma_transfer(uint32_t addr, int size)
+{
+	/* set up the next DMA transfer */
+	dma_out(dma_chan, addr, size, DMA_SINGLE);
+
+	/* program the DSP to accept the DMA transfer */
+	write_dsp(CMD_START_DMA8 | CMD_FIFO);
+	write_dsp(xfer_mode);
+	size--;
+	write_dsp(size & 0xff);
+	write_dsp((size >> 8) & 0xff);
+}
+
 static void write_dsp(unsigned char val)
 {
 	while(inb(REG_WSTAT) & WSTAT_BUSY);

src/au_sb.c

@@ -28,4 +28,15 @@ int sb_detect(void);
  */
 int sb_reset_dsp(void);
 
+void *sb_buffer(int *size);
+
+void sb_set_output_rate(int rate);
+
+void sb_start(int rate, int nchan);
+void sb_pause(void);
+void sb_continue(void);
+void sb_stop(void);
+
+void sb_volume(int vol);
+
 #endif	/* AU_SB_H_ */

src/au_sb.h

@@ -19,12 +19,70 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include "audio.h"
 #include "au_sb.h"
 
-void init_audio(void)
+struct audrv {
+	void *(*get_buffer)(int *size);
+	void (*start)(int rate, int nchan);
+	void (*pause)(void);
+	void (*cont)(void);
+	void (*stop)(void);
+	void (*volume)(int vol);
+};
+
+static struct audrv drv;
+
+static audio_callback_func cbfunc;
+static void *cbcls;
+
+void audio_init(void)
 {
 	if(sb_detect()) {
-		/* TODO use the sound blaster */
+		drv.get_buffer = sb_buffer;
+		drv.start = sb_start;
+		drv.pause = sb_pause;
+		drv.cont = sb_continue;
+		drv.stop = sb_stop;
+		drv.volume = sb_volume;
 		return;
 	}
 
 	printf("No supported audio device detected\n");
 }
+
+void audio_set_callback(audio_callback_func func, void *cls)
+{
+	cbfunc = func;
+	cbcls = cls;
+}
+
+int audio_callback(void *buf, int sz)
+{
+	if(!cbfunc) {
+		return 0;
+	}
+	return cbfunc(buf, sz, cbcls);
+}
+
+void audio_play(int rate, int nchan)
+{
+	drv.start(rate, nchan);
+}
+
+void audio_pause(void)
+{
+	drv.pause();
+}
+
+void audio_resume(void)
+{
+	drv.cont();
+}
+
+void audio_stop(void)
+{
+	drv.stop();
+}
+
+void audio_volume(int vol)
+{
+	drv.volume(vol);
+}

src/audio.c

@@ -18,6 +18,18 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #ifndef AUDIO_H_
 #define AUDIO_H_
 
-void init_audio(void);
+typedef int (*audio_callback_func)(void *buffer, int size, void *cls);
+
+void audio_init(void);
+
+void audio_set_callback(audio_callback_func func, void *cls);
+int audio_callback(void *buf, int sz);
+
+void audio_play(int rate, int nchan);
+void audio_pause(void);
+void audio_resume(void);
+void audio_stop(void);
+
+void audio_volume(int vol);
 
 #endif	/* AUDIO_H_ */