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-rw-r--r--src/mess/audio/socrates.c165
1 files changed, 165 insertions, 0 deletions
diff --git a/src/mess/audio/socrates.c b/src/mess/audio/socrates.c
new file mode 100644
index 00000000000..1fde923d002
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+++ b/src/mess/audio/socrates.c
@@ -0,0 +1,165 @@
+/***************************************************************************
+
+ audio/socrates.c
+
+ This handles the two squarewaves (plus the one weird wave) channels
+ on the V-tech Socrates system 27-0769 ASIC.
+
+****************************************************************************/
+
+#include "emu.h"
+#include "socrates.h"
+
+typedef struct
+{
+ sound_stream *stream;
+ UINT8 freq[2]; /* channel 1,2 frequencies */
+ UINT8 vol[2]; /* channel 1,2 volume */
+ UINT8 enable[2]; /* channel 1,2 enable */
+ UINT8 channel3; /* channel 3 weird register */
+ UINT8 state[3]; /* output states for channels 1,2,3 */
+ UINT8 accum[3]; /* accumulators for channels 1,2,3 */
+ UINT16 DAC_output; /* output */
+} SocratesASIC;
+
+
+INLINE SocratesASIC *get_safe_token(device_t *device)
+{
+ assert(device != NULL);
+ assert(device->type() == SOCRATES);
+ return (SocratesASIC *)downcast<legacy_device_base *>(device)->token();
+}
+
+static const UINT8 volumeLUT[16] =
+{
+0, 61, 100, 132, 158, 183, 201, 218,
+233, 242, 253, 255, 250, 240, 224, 211
+}; // this table is actually quite weird on the real console.
+// 0, 0.033, 0.055, 0.07175, 0.086, 0.1, 0.11, 0.119, 0.127, 0.132, 0.138, 0.139, 0.136, 0.131, 0.122, 0.115 are the voltage amplitudes for the steps on channel 2. the last four are particularly bizarre, probably caused by some sort of internal clipping.
+static void socrates_snd_clock(SocratesASIC *chip) /* called once per clock */
+{
+ int channel;
+ for (channel = 0; channel < 2; channel++)
+ {
+ if ((chip->accum[channel] == 0) && chip->enable[channel])
+ {
+ chip->state[channel] = (chip->state[channel]^0x1);
+ chip->accum[channel] = chip->freq[channel];
+ }
+ else if (chip->enable[channel])
+ {
+ chip->accum[channel]--;
+ }
+ else
+ {
+ chip->accum[channel] = 0; // channel is disabled
+ chip->state[channel] = 0;
+ }
+ }
+ // handle channel 3 here
+ chip->DAC_output = (chip->state[0]?(volumeLUT[chip->vol[0]]*9.4):0); // channel 1 is ~2.4 times as loud as channel 2
+ chip->DAC_output += (chip->state[1]?(volumeLUT[chip->vol[1]]<<2):0);
+ // add channel 3 to dac output here
+}
+
+/*************************************
+ *
+ * Stream updater
+ *
+ *************************************/
+static STREAM_UPDATE( socrates_snd_pcm_update )
+{
+ SocratesASIC *chip = (SocratesASIC *)param;
+ int i;
+
+ for (i = 0; i < samples; i++)
+ {
+ socrates_snd_clock(chip);
+ outputs[0][i] = ((int)chip->DAC_output<<4);
+ }
+}
+
+
+
+/*************************************
+ *
+ * Sound handler start
+ *
+ *************************************/
+
+static DEVICE_START( socrates_snd )
+{
+ SocratesASIC *chip = get_safe_token(device);
+ chip->freq[0] = chip->freq[1] = 0xff; /* channel 1,2 frequency */
+ chip->vol[0] = chip->vol[1] = 0x07; /* channel 1,2 volume */
+ chip->enable[0] = chip->enable[1] = 0x01; /* channel 1,2 enable */
+ chip->channel3 = 0x00; /* channel 3 weird register */
+ chip->DAC_output = 0x00; /* output */
+ chip->state[0] = chip->state[1] = chip->state[2] = 0;
+ chip->accum[0] = chip->accum[1] = chip->accum[2] = 0xFF;
+ chip->stream = device->machine().sound().stream_alloc(*device, 0, 1, device->clock() ? device->clock() : device->machine().sample_rate(), chip, socrates_snd_pcm_update);
+}
+
+
+void socrates_snd_reg0_w(device_t *device, int data)
+{
+ SocratesASIC *chip = get_safe_token(device);
+ chip->stream->update();
+ chip->freq[0] = data;
+}
+
+void socrates_snd_reg1_w(device_t *device, int data)
+{
+ SocratesASIC *chip = get_safe_token(device);
+ chip->stream->update();
+ chip->freq[1] = data;
+}
+
+void socrates_snd_reg2_w(device_t *device, int data)
+{
+ SocratesASIC *chip = get_safe_token(device);
+ chip->stream->update();
+ chip->vol[0] = data&0xF;
+ chip->enable[0] = (data&0x10)>>4;
+}
+
+void socrates_snd_reg3_w(device_t *device, int data)
+{
+ SocratesASIC *chip = get_safe_token(device);
+ chip->stream->update();
+ chip->vol[1] = data&0xF;
+ chip->enable[1] = (data&0x10)>>4;
+}
+
+void socrates_snd_reg4_w(device_t *device, int data)
+{
+ SocratesASIC *chip = get_safe_token(device);
+ chip->stream->update();
+ chip->channel3 = data;
+}
+
+
+/**************************************************************************
+ * Generic get_info
+ **************************************************************************/
+
+DEVICE_GET_INFO( socrates_snd )
+{
+ switch (state)
+ {
+ /* --- the following bits of info are returned as 64-bit signed integers --- */
+ case DEVINFO_INT_TOKEN_BYTES: info->i = sizeof(SocratesASIC); break;
+
+ /* --- the following bits of info are returned as pointers to data or functions --- */
+ case DEVINFO_FCT_START: info->start = DEVICE_START_NAME( socrates_snd ); break;
+
+ /* --- the following bits of info are returned as NULL-terminated strings --- */
+ case DEVINFO_STR_NAME: strcpy(info->s, "Socrates Sound"); break;
+ case DEVINFO_STR_FAMILY: strcpy(info->s, "Socrates Sound"); 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 Jonathan Gevaryahu and The MESS Team"); break;
+ }
+}
+
+DEFINE_LEGACY_SOUND_DEVICE(SOCRATES, socrates_snd);