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-rw-r--r--trunk/src/emu/sound/dac.c166
1 files changed, 166 insertions, 0 deletions
diff --git a/trunk/src/emu/sound/dac.c b/trunk/src/emu/sound/dac.c
new file mode 100644
index 00000000000..c18bb00cdcc
--- /dev/null
+++ b/trunk/src/emu/sound/dac.c
@@ -0,0 +1,166 @@
+#include "emu.h"
+#include "dac.h"
+
+
+/* default to 4x oversampling */
+#define DEFAULT_SAMPLE_RATE (48000 * 4)
+
+
+typedef struct _dac_state dac_state;
+struct _dac_state
+{
+ sound_stream *channel;
+ INT16 output;
+ INT16 UnsignedVolTable[256];
+ INT16 SignedVolTable[256];
+};
+
+
+INLINE dac_state *get_safe_token(device_t *device)
+{
+ assert(device != NULL);
+ assert(device->type() == DAC);
+ return (dac_state *)downcast<legacy_device_base *>(device)->token();
+}
+
+
+static STREAM_UPDATE( DAC_update )
+{
+ dac_state *info = (dac_state *)param;
+ stream_sample_t *buffer = outputs[0];
+ INT16 out = info->output;
+
+ while (samples--) *(buffer++) = out;
+}
+
+
+void dac_data_w(device_t *device, UINT8 data)
+{
+ dac_state *info = get_safe_token(device);
+ INT16 out = info->UnsignedVolTable[data];
+
+ if (info->output != out)
+ {
+ /* update the output buffer before changing the registers */
+ info->channel->update();
+ info->output = out;
+ }
+}
+
+
+void dac_signed_data_w(device_t *device, UINT8 data)
+{
+ dac_state *info = get_safe_token(device);
+ INT16 out = info->SignedVolTable[data];
+
+ if (info->output != out)
+ {
+ /* update the output buffer before changing the registers */
+ info->channel->update();
+ info->output = out;
+ }
+}
+
+
+void dac_data_16_w(device_t *device, UINT16 data)
+{
+ dac_state *info = get_safe_token(device);
+ INT16 out = data >> 1; /* range 0..32767 */
+
+ if (info->output != out)
+ {
+ /* update the output buffer before changing the registers */
+ info->channel->update();
+ info->output = out;
+ }
+}
+
+
+void dac_signed_data_16_w(device_t *device, UINT16 data)
+{
+ dac_state *info = get_safe_token(device);
+ INT16 out = (INT32)data - (INT32)0x08000; /* range -32768..32767 */
+ /* casts avoid potential overflow on some ABIs */
+
+ if (info->output != out)
+ {
+ /* update the output buffer before changing the registers */
+ info->channel->update();
+ info->output = out;
+ }
+}
+
+
+INT16 dac_output(device_t *device)
+{
+ dac_state *info = get_safe_token(device);
+ return info->output;
+}
+
+
+static void DAC_build_voltable(dac_state *info)
+{
+ int i;
+
+ /* build volume table (linear) */
+ for (i = 0;i < 256;i++)
+ {
+ info->UnsignedVolTable[i] = i * 0x101 / 2; /* range 0..32767 */
+ info->SignedVolTable[i] = i * 0x101 - 0x8000; /* range -32768..32767 */
+ }
+}
+
+
+static DEVICE_START( dac )
+{
+ dac_state *info = get_safe_token(device);
+
+ DAC_build_voltable(info);
+
+ info->channel = device->machine().sound().stream_alloc(*device,0,1,device->clock() ? device->clock() : DEFAULT_SAMPLE_RATE,info,DAC_update);
+ info->output = 0;
+
+ device->save_item(NAME(info->output));
+}
+
+
+
+WRITE8_DEVICE_HANDLER( dac_w )
+{
+ dac_data_w(device, data);
+}
+
+WRITE8_DEVICE_HANDLER( dac_signed_w )
+{
+ dac_signed_data_w(device, data);
+}
+
+
+
+/**************************************************************************
+ * Generic get_info
+ **************************************************************************/
+
+DEVICE_GET_INFO( dac )
+{
+ switch (state)
+ {
+ /* --- the following bits of info are returned as 64-bit signed integers --- */
+ case DEVINFO_INT_TOKEN_BYTES: info->i = sizeof(dac_state); break;
+
+ /* --- the following bits of info are returned as pointers to data or functions --- */
+ case DEVINFO_FCT_START: info->start = DEVICE_START_NAME( dac ); break;
+ case DEVINFO_FCT_STOP: /* nothing */ break;
+ case DEVINFO_FCT_RESET: /* nothing */ break;
+
+ /* --- the following bits of info are returned as NULL-terminated strings --- */
+ case DEVINFO_STR_NAME: strcpy(info->s, "DAC"); break;
+ case DEVINFO_STR_FAMILY: strcpy(info->s, "DAC"); break;
+ case DEVINFO_STR_VERSION: strcpy(info->s, "1.0"); break;
+ case DEVINFO_STR_SOURCE_FILE: strcpy(info->s, __FILE__); break;
+ case DEVINFO_STR_CREDITS: strcpy(info->s, "Copyright Nicola Salmoria and the MAME Team"); break;
+ }
+}
+
+
+DEFINE_LEGACY_SOUND_DEVICE(DAC, dac);