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-rw-r--r--src/mess/audio/gb.c775
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diff --git a/src/mess/audio/gb.c b/src/mess/audio/gb.c
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+/**************************************************************************************
+* Game Boy sound emulation (c) Anthony Kruize (trandor@labyrinth.net.au)
+*
+* Anyways, sound on the Game Boy consists of 4 separate 'channels'
+* Sound1 = Quadrangular waves with SWEEP and ENVELOPE functions (NR10,11,12,13,14)
+* Sound2 = Quadrangular waves with ENVELOPE functions (NR21,22,23,24)
+* Sound3 = Wave patterns from WaveRAM (NR30,31,32,33,34)
+* Sound4 = White noise with an envelope (NR41,42,43,44)
+*
+* Each sound channel has 2 modes, namely ON and OFF... whoa
+*
+* These tend to be the two most important equations in
+* converting between Hertz and GB frequency registers:
+* (Sounds will have a 2.4% higher frequency on Super GB.)
+* gb = 2048 - (131072 / Hz)
+* Hz = 131072 / (2048 - gb)
+*
+* Changes:
+*
+* 10/2/2002 AK - Preliminary sound code.
+* 13/2/2002 AK - Added a hack for mode 4, other fixes.
+* 23/2/2002 AK - Use lookup tables, added sweep to mode 1. Re-wrote the square
+* wave generation.
+* 13/3/2002 AK - Added mode 3, better lookup tables, other adjustments.
+* 15/3/2002 AK - Mode 4 can now change frequencies.
+* 31/3/2002 AK - Accidently forgot to handle counter/consecutive for mode 1.
+* 3/4/2002 AK - Mode 1 sweep can still occur if shift is 0. Don't let frequency
+* go past the maximum allowed value. Fixed Mode 3 length table.
+* Slight adjustment to Mode 4's period table generation.
+* 5/4/2002 AK - Mode 4 is done correctly, using a polynomial counter instead
+* of being a total hack.
+* 6/4/2002 AK - Slight tweak to mode 3's frequency calculation.
+* 13/4/2002 AK - Reset envelope value when sound is initialized.
+* 21/4/2002 AK - Backed out the mode 3 frequency calculation change.
+* Merged init functions into gameboy_sound_w().
+* 14/5/2002 AK - Removed magic numbers in the fixed point math.
+* 12/6/2002 AK - Merged SOUNDx structs into one SOUND struct.
+* 26/10/2002 AK - Finally fixed channel 3!
+*
+***************************************************************************************/
+
+#include "emu.h"
+#include "gb.h"
+
+
+/***************************************************************************
+ CONSTANTS
+***************************************************************************/
+
+#define NR10 0x00
+#define NR11 0x01
+#define NR12 0x02
+#define NR13 0x03
+#define NR14 0x04
+#define NR21 0x06
+#define NR22 0x07
+#define NR23 0x08
+#define NR24 0x09
+#define NR30 0x0A
+#define NR31 0x0B
+#define NR32 0x0C
+#define NR33 0x0D
+#define NR34 0x0E
+#define NR41 0x10
+#define NR42 0x11
+#define NR43 0x12
+#define NR44 0x13
+#define NR50 0x14
+#define NR51 0x15
+#define NR52 0x16
+#define AUD3W0 0x20
+#define AUD3W1 0x21
+#define AUD3W2 0x22
+#define AUD3W3 0x23
+#define AUD3W4 0x24
+#define AUD3W5 0x25
+#define AUD3W6 0x26
+#define AUD3W7 0x27
+#define AUD3W8 0x28
+#define AUD3W9 0x29
+#define AUD3WA 0x2A
+#define AUD3WB 0x2B
+#define AUD3WC 0x2C
+#define AUD3WD 0x2D
+#define AUD3WE 0x2E
+#define AUD3WF 0x2F
+
+#define LEFT 1
+#define RIGHT 2
+#define MAX_FREQUENCIES 2048
+#define FIXED_POINT 16
+
+/* Represents wave duties of 12.5%, 25%, 50% and 75% */
+static const float wave_duty_table[4] = { 8.0f, 4.0f, 2.0f, 1.33f };
+
+
+/***************************************************************************
+ TYPE DEFINITIONS
+***************************************************************************/
+
+struct SOUND
+{
+ /* Common */
+ UINT8 on;
+ UINT8 channel;
+ INT32 length;
+ INT32 pos;
+ UINT32 period;
+ INT32 count;
+ INT8 mode;
+ /* Mode 1, 2, 3 */
+ INT8 duty;
+ /* Mode 1, 2, 4 */
+ INT32 env_value;
+ INT8 env_direction;
+ INT32 env_length;
+ INT32 env_count;
+ INT8 signal;
+ /* Mode 1 */
+ UINT32 frequency;
+ INT32 swp_shift;
+ INT32 swp_direction;
+ INT32 swp_time;
+ INT32 swp_count;
+ /* Mode 3 */
+ INT8 level;
+ UINT8 offset;
+ UINT32 dutycount;
+ /* Mode 4 */
+ INT32 ply_step;
+ INT16 ply_value;
+};
+
+struct SOUNDC
+{
+ UINT8 on;
+ UINT8 vol_left;
+ UINT8 vol_right;
+ UINT8 mode1_left;
+ UINT8 mode1_right;
+ UINT8 mode2_left;
+ UINT8 mode2_right;
+ UINT8 mode3_left;
+ UINT8 mode3_right;
+ UINT8 mode4_left;
+ UINT8 mode4_right;
+};
+
+
+typedef struct _gb_sound_t gb_sound_t;
+struct _gb_sound_t
+{
+ sound_stream *channel;
+ int rate;
+
+ INT32 env_length_table[8];
+ INT32 swp_time_table[8];
+ UINT32 period_table[MAX_FREQUENCIES];
+ UINT32 period_mode3_table[MAX_FREQUENCIES];
+ UINT32 period_mode4_table[8][16];
+ UINT32 length_table[64];
+ UINT32 length_mode3_table[256];
+
+ struct SOUND snd_1;
+ struct SOUND snd_2;
+ struct SOUND snd_3;
+ struct SOUND snd_4;
+ struct SOUNDC snd_control;
+
+ UINT8 snd_regs[0x30];
+};
+
+
+
+/***************************************************************************
+ INLINE FUNCTIONS
+***************************************************************************/
+
+INLINE gb_sound_t *get_token(device_t *device)
+{
+ assert(device != NULL);
+ assert(device->type() == GAMEBOY);
+ return (gb_sound_t *) downcast<legacy_device_base *>(device)->token();
+}
+
+
+/***************************************************************************
+ PROTOTYPES
+***************************************************************************/
+
+static STREAM_UPDATE( gameboy_update );
+
+
+/***************************************************************************
+ IMPLEMENTATION
+***************************************************************************/
+
+READ8_DEVICE_HANDLER( gb_wave_r )
+{
+ gb_sound_t *gb = get_token(device);
+
+ /* TODO: properly emulate scrambling of wave ram area when playback is active */
+ return ( gb->snd_regs[ AUD3W0 + offset ] | gb->snd_3.on );
+}
+
+WRITE8_DEVICE_HANDLER( gb_wave_w )
+{
+ gb_sound_t *gb = get_token(device);
+ gb->snd_regs[ AUD3W0 + offset ] = data;
+}
+
+READ8_DEVICE_HANDLER( gb_sound_r )
+{
+ gb_sound_t *gb = get_token(device);
+
+ switch( offset ) {
+ case 0x05:
+ case 0x0F:
+ return 0xFF;
+ case NR52:
+ return 0x70 | gb->snd_regs[offset];
+ default:
+ return gb->snd_regs[offset];
+ }
+}
+
+static void gb_sound_w_internal(device_t *device, int offset, UINT8 data )
+{
+ gb_sound_t *gb = get_token(device);
+
+ /* Store the value */
+ gb->snd_regs[offset] = data;
+
+ switch( offset )
+ {
+ /*MODE 1 */
+ case NR10: /* Sweep (R/W) */
+ gb->snd_1.swp_shift = data & 0x7;
+ gb->snd_1.swp_direction = (data & 0x8) >> 3;
+ gb->snd_1.swp_direction |= gb->snd_1.swp_direction - 1;
+ gb->snd_1.swp_time = gb->swp_time_table[ (data & 0x70) >> 4 ];
+ break;
+ case NR11: /* Sound length/Wave pattern duty (R/W) */
+ gb->snd_1.duty = (data & 0xC0) >> 6;
+ gb->snd_1.length = gb->length_table[data & 0x3F];
+ break;
+ case NR12: /* Envelope (R/W) */
+ gb->snd_1.env_value = data >> 4;
+ gb->snd_1.env_direction = (data & 0x8) >> 3;
+ gb->snd_1.env_direction |= gb->snd_1.env_direction - 1;
+ gb->snd_1.env_length = gb->env_length_table[data & 0x7];
+ break;
+ case NR13: /* Frequency lo (R/W) */
+ gb->snd_1.frequency = ((gb->snd_regs[NR14]&0x7)<<8) | gb->snd_regs[NR13];
+ gb->snd_1.period = gb->period_table[gb->snd_1.frequency];
+ break;
+ case NR14: /* Frequency hi / Initialize (R/W) */
+ gb->snd_1.mode = (data & 0x40) >> 6;
+ gb->snd_1.frequency = ((gb->snd_regs[NR14]&0x7)<<8) | gb->snd_regs[NR13];
+ gb->snd_1.period = gb->period_table[gb->snd_1.frequency];
+ if( data & 0x80 )
+ {
+ if( !gb->snd_1.on )
+ gb->snd_1.pos = 0;
+ gb->snd_1.on = 1;
+ gb->snd_1.count = 0;
+ gb->snd_1.env_value = gb->snd_regs[NR12] >> 4;
+ gb->snd_1.env_count = 0;
+ gb->snd_1.swp_count = 0;
+ gb->snd_1.signal = 0x1;
+ gb->snd_regs[NR52] |= 0x1;
+ }
+ break;
+
+ /*MODE 2 */
+ case NR21: /* Sound length/Wave pattern duty (R/W) */
+ gb->snd_2.duty = (data & 0xC0) >> 6;
+ gb->snd_2.length = gb->length_table[data & 0x3F];
+ break;
+ case NR22: /* Envelope (R/W) */
+ gb->snd_2.env_value = data >> 4;
+ gb->snd_2.env_direction = (data & 0x8 ) >> 3;
+ gb->snd_2.env_direction |= gb->snd_2.env_direction - 1;
+ gb->snd_2.env_length = gb->env_length_table[data & 0x7];
+ break;
+ case NR23: /* Frequency lo (R/W) */
+ gb->snd_2.period = gb->period_table[((gb->snd_regs[NR24]&0x7)<<8) | gb->snd_regs[NR23]];
+ break;
+ case NR24: /* Frequency hi / Initialize (R/W) */
+ gb->snd_2.mode = (data & 0x40) >> 6;
+ gb->snd_2.period = gb->period_table[((gb->snd_regs[NR24]&0x7)<<8) | gb->snd_regs[NR23]];
+ if( data & 0x80 )
+ {
+ if( !gb->snd_2.on )
+ gb->snd_2.pos = 0;
+ gb->snd_2.on = 1;
+ gb->snd_2.count = 0;
+ gb->snd_2.env_value = gb->snd_regs[NR22] >> 4;
+ gb->snd_2.env_count = 0;
+ gb->snd_2.signal = 0x1;
+ gb->snd_regs[NR52] |= 0x2;
+ }
+ break;
+
+ /*MODE 3 */
+ case NR30: /* Sound On/Off (R/W) */
+ gb->snd_3.on = (data & 0x80) >> 7;
+ break;
+ case NR31: /* Sound Length (R/W) */
+ gb->snd_3.length = gb->length_mode3_table[data];
+ break;
+ case NR32: /* Select Output Level */
+ gb->snd_3.level = (data & 0x60) >> 5;
+ break;
+ case NR33: /* Frequency lo (W) */
+ gb->snd_3.period = gb->period_mode3_table[((gb->snd_regs[NR34]&0x7)<<8) + gb->snd_regs[NR33]];
+ break;
+ case NR34: /* Frequency hi / Initialize (W) */
+ gb->snd_3.mode = (data & 0x40) >> 6;
+ gb->snd_3.period = gb->period_mode3_table[((gb->snd_regs[NR34]&0x7)<<8) + gb->snd_regs[NR33]];
+ if( data & 0x80 )
+ {
+ if( !gb->snd_3.on )
+ {
+ gb->snd_3.pos = 0;
+ gb->snd_3.offset = 0;
+ gb->snd_3.duty = 0;
+ }
+ gb->snd_3.on = 1;
+ gb->snd_3.count = 0;
+ gb->snd_3.duty = 1;
+ gb->snd_3.dutycount = 0;
+ gb->snd_regs[NR52] |= 0x4;
+ }
+ break;
+
+ /*MODE 4 */
+ case NR41: /* Sound Length (R/W) */
+ gb->snd_4.length = gb->length_table[data & 0x3F];
+ break;
+ case NR42: /* Envelope (R/W) */
+ gb->snd_4.env_value = data >> 4;
+ gb->snd_4.env_direction = (data & 0x8 ) >> 3;
+ gb->snd_4.env_direction |= gb->snd_4.env_direction - 1;
+ gb->snd_4.env_length = gb->env_length_table[data & 0x7];
+ break;
+ case NR43: /* Polynomial Counter/Frequency */
+ gb->snd_4.period = gb->period_mode4_table[data & 0x7][(data & 0xF0) >> 4];
+ gb->snd_4.ply_step = (data & 0x8) >> 3;
+ break;
+ case NR44: /* Counter/Consecutive / Initialize (R/W) */
+ gb->snd_4.mode = (data & 0x40) >> 6;
+ if( data & 0x80 )
+ {
+ if( !gb->snd_4.on )
+ gb->snd_4.pos = 0;
+ gb->snd_4.on = 1;
+ gb->snd_4.count = 0;
+ gb->snd_4.env_value = gb->snd_regs[NR42] >> 4;
+ gb->snd_4.env_count = 0;
+ gb->snd_4.signal = device->machine().rand();
+ gb->snd_4.ply_value = 0x7fff;
+ gb->snd_regs[NR52] |= 0x8;
+ }
+ break;
+
+ /* CONTROL */
+ case NR50: /* Channel Control / On/Off / Volume (R/W) */
+ gb->snd_control.vol_left = data & 0x7;
+ gb->snd_control.vol_right = (data & 0x70) >> 4;
+ break;
+ case NR51: /* Selection of Sound Output Terminal */
+ gb->snd_control.mode1_right = data & 0x1;
+ gb->snd_control.mode1_left = (data & 0x10) >> 4;
+ gb->snd_control.mode2_right = (data & 0x2) >> 1;
+ gb->snd_control.mode2_left = (data & 0x20) >> 5;
+ gb->snd_control.mode3_right = (data & 0x4) >> 2;
+ gb->snd_control.mode3_left = (data & 0x40) >> 6;
+ gb->snd_control.mode4_right = (data & 0x8) >> 3;
+ gb->snd_control.mode4_left = (data & 0x80) >> 7;
+ break;
+ case NR52: /* Sound On/Off (R/W) */
+ /* Only bit 7 is writable, writing to bits 0-3 does NOT enable or
+ disable sound. They are read-only */
+ gb->snd_control.on = (data & 0x80) >> 7;
+ if( !gb->snd_control.on )
+ {
+ gb_sound_w_internal( device, NR10, 0x80 );
+ gb_sound_w_internal( device, NR11, 0x3F );
+ gb_sound_w_internal( device, NR12, 0x00 );
+ gb_sound_w_internal( device, NR13, 0xFE );
+ gb_sound_w_internal( device, NR14, 0xBF );
+// gb_sound_w_internal( device, NR20, 0xFF );
+ gb_sound_w_internal( device, NR21, 0x3F );
+ gb_sound_w_internal( device, NR22, 0x00 );
+ gb_sound_w_internal( device, NR23, 0xFF );
+ gb_sound_w_internal( device, NR24, 0xBF );
+ gb_sound_w_internal( device, NR30, 0x7F );
+ gb_sound_w_internal( device, NR31, 0xFF );
+ gb_sound_w_internal( device, NR32, 0x9F );
+ gb_sound_w_internal( device, NR33, 0xFF );
+ gb_sound_w_internal( device, NR34, 0xBF );
+// gb_sound_w_internal( device, NR40, 0xFF );
+ gb_sound_w_internal( device, NR41, 0xFF );
+ gb_sound_w_internal( device, NR42, 0x00 );
+ gb_sound_w_internal( device, NR43, 0x00 );
+ gb_sound_w_internal( device, NR44, 0xBF );
+ gb_sound_w_internal( device, NR50, 0x00 );
+ gb_sound_w_internal( device, NR51, 0x00 );
+ gb->snd_1.on = 0;
+ gb->snd_2.on = 0;
+ gb->snd_3.on = 0;
+ gb->snd_4.on = 0;
+ gb->snd_regs[offset] = 0;
+ }
+ break;
+ }
+}
+
+WRITE8_DEVICE_HANDLER( gb_sound_w )
+{
+ gb_sound_t *gb = get_token(device);
+
+ /* change in registers so update first */
+ gb->channel->update();
+
+ /* Only register NR52 is accessible if the sound controller is disabled */
+ if( !gb->snd_control.on && offset != NR52 )
+ {
+ return;
+ }
+
+ gb_sound_w_internal( device, offset, data );
+}
+
+
+
+static STREAM_UPDATE( gameboy_update )
+{
+ gb_sound_t *gb = get_token(device);
+ stream_sample_t sample, left, right, mode4_mask;
+
+ while( samples-- > 0 )
+ {
+ left = right = 0;
+
+ /* Mode 1 - Wave with Envelope and Sweep */
+ if( gb->snd_1.on )
+ {
+ sample = gb->snd_1.signal * gb->snd_1.env_value;
+ gb->snd_1.pos++;
+ if( gb->snd_1.pos == (UINT32)(gb->snd_1.period / wave_duty_table[gb->snd_1.duty]) >> FIXED_POINT)
+ {
+ gb->snd_1.signal = -gb->snd_1.signal;
+ }
+ else if( gb->snd_1.pos > (gb->snd_1.period >> FIXED_POINT) )
+ {
+ gb->snd_1.pos = 0;
+ gb->snd_1.signal = -gb->snd_1.signal;
+ }
+
+ if( gb->snd_1.length && gb->snd_1.mode )
+ {
+ gb->snd_1.count++;
+ if( gb->snd_1.count >= gb->snd_1.length )
+ {
+ gb->snd_1.on = 0;
+ gb->snd_regs[NR52] &= 0xFE;
+ }
+ }
+
+ if( gb->snd_1.env_length )
+ {
+ gb->snd_1.env_count++;
+ if( gb->snd_1.env_count >= gb->snd_1.env_length )
+ {
+ gb->snd_1.env_count = 0;
+ gb->snd_1.env_value += gb->snd_1.env_direction;
+ if( gb->snd_1.env_value < 0 )
+ gb->snd_1.env_value = 0;
+ if( gb->snd_1.env_value > 15 )
+ gb->snd_1.env_value = 15;
+ }
+ }
+
+ if( gb->snd_1.swp_time )
+ {
+ gb->snd_1.swp_count++;
+ if( gb->snd_1.swp_count >= gb->snd_1.swp_time )
+ {
+ gb->snd_1.swp_count = 0;
+ if( gb->snd_1.swp_direction > 0 )
+ {
+ gb->snd_1.frequency -= gb->snd_1.frequency / (1 << gb->snd_1.swp_shift );
+ if( gb->snd_1.frequency <= 0 )
+ {
+ gb->snd_1.on = 0;
+ gb->snd_regs[NR52] &= 0xFE;
+ }
+ }
+ else
+ {
+ gb->snd_1.frequency += gb->snd_1.frequency / (1 << gb->snd_1.swp_shift );
+ if( gb->snd_1.frequency >= MAX_FREQUENCIES )
+ {
+ gb->snd_1.frequency = MAX_FREQUENCIES - 1;
+ }
+ }
+
+ gb->snd_1.period = gb->period_table[gb->snd_1.frequency];
+ }
+ }
+
+ if( gb->snd_control.mode1_left )
+ left += sample;
+ if( gb->snd_control.mode1_right )
+ right += sample;
+ }
+
+ /* Mode 2 - Wave with Envelope */
+ if( gb->snd_2.on )
+ {
+ sample = gb->snd_2.signal * gb->snd_2.env_value;
+ gb->snd_2.pos++;
+ if( gb->snd_2.pos == (UINT32)(gb->snd_2.period / wave_duty_table[gb->snd_2.duty]) >> FIXED_POINT)
+ {
+ gb->snd_2.signal = -gb->snd_2.signal;
+ }
+ else if( gb->snd_2.pos > (gb->snd_2.period >> FIXED_POINT) )
+ {
+ gb->snd_2.pos = 0;
+ gb->snd_2.signal = -gb->snd_2.signal;
+ }
+
+ if( gb->snd_2.length && gb->snd_2.mode )
+ {
+ gb->snd_2.count++;
+ if( gb->snd_2.count >= gb->snd_2.length )
+ {
+ gb->snd_2.on = 0;
+ gb->snd_regs[NR52] &= 0xFD;
+ }
+ }
+
+ if( gb->snd_2.env_length )
+ {
+ gb->snd_2.env_count++;
+ if( gb->snd_2.env_count >= gb->snd_2.env_length )
+ {
+ gb->snd_2.env_count = 0;
+ gb->snd_2.env_value += gb->snd_2.env_direction;
+ if( gb->snd_2.env_value < 0 )
+ gb->snd_2.env_value = 0;
+ if( gb->snd_2.env_value > 15 )
+ gb->snd_2.env_value = 15;
+ }
+ }
+
+ if( gb->snd_control.mode2_left )
+ left += sample;
+ if( gb->snd_control.mode2_right )
+ right += sample;
+ }
+
+ /* Mode 3 - Wave patterns from WaveRAM */
+ if( gb->snd_3.on )
+ {
+ /* NOTE: This is extremely close, but not quite right.
+ The problem is for GB frequencies above 2000 the frequency gets
+ clipped. This is caused because gb->snd_3.pos is never 0 at the test.*/
+ sample = gb->snd_regs[AUD3W0 + (gb->snd_3.offset/2)];
+ if( !(gb->snd_3.offset % 2) )
+ {
+ sample >>= 4;
+ }
+ sample = (sample & 0xF) - 8;
+
+ if( gb->snd_3.level )
+ sample >>= (gb->snd_3.level - 1);
+ else
+ sample = 0;
+
+ gb->snd_3.pos++;
+ if( gb->snd_3.pos >= ((UINT32)(((gb->snd_3.period ) >> 21)) + gb->snd_3.duty) )
+ {
+ gb->snd_3.pos = 0;
+ if( gb->snd_3.dutycount == ((UINT32)(((gb->snd_3.period ) >> FIXED_POINT)) % 32) )
+ {
+ gb->snd_3.duty--;
+ }
+ gb->snd_3.dutycount++;
+ gb->snd_3.offset++;
+ if( gb->snd_3.offset > 31 )
+ {
+ gb->snd_3.offset = 0;
+ gb->snd_3.duty = 1;
+ gb->snd_3.dutycount = 0;
+ }
+ }
+
+ if( gb->snd_3.length && gb->snd_3.mode )
+ {
+ gb->snd_3.count++;
+ if( gb->snd_3.count >= gb->snd_3.length )
+ {
+ gb->snd_3.on = 0;
+ gb->snd_regs[NR52] &= 0xFB;
+ }
+ }
+
+ if( gb->snd_control.mode3_left )
+ left += sample;
+ if( gb->snd_control.mode3_right )
+ right += sample;
+ }
+
+ /* Mode 4 - Noise with Envelope */
+ if( gb->snd_4.on )
+ {
+ /* Similar problem to Mode 3, we seem to miss some notes */
+ sample = gb->snd_4.signal & gb->snd_4.env_value;
+ gb->snd_4.pos++;
+ if( gb->snd_4.pos == (gb->snd_4.period >> (FIXED_POINT + 1)) )
+ {
+ /* Using a Polynomial Counter (aka Linear Feedback Shift Register)
+ Mode 4 has a 7 bit and 15 bit counter so we need to shift the
+ bits around accordingly */
+ mode4_mask = (((gb->snd_4.ply_value & 0x2) >> 1) ^ (gb->snd_4.ply_value & 0x1)) << (gb->snd_4.ply_step ? 6 : 14);
+ gb->snd_4.ply_value >>= 1;
+ gb->snd_4.ply_value |= mode4_mask;
+ gb->snd_4.ply_value &= (gb->snd_4.ply_step ? 0x7f : 0x7fff);
+ gb->snd_4.signal = (INT8)gb->snd_4.ply_value;
+ }
+ else if( gb->snd_4.pos > (gb->snd_4.period >> FIXED_POINT) )
+ {
+ gb->snd_4.pos = 0;
+ mode4_mask = (((gb->snd_4.ply_value & 0x2) >> 1) ^ (gb->snd_4.ply_value & 0x1)) << (gb->snd_4.ply_step ? 6 : 14);
+ gb->snd_4.ply_value >>= 1;
+ gb->snd_4.ply_value |= mode4_mask;
+ gb->snd_4.ply_value &= (gb->snd_4.ply_step ? 0x7f : 0x7fff);
+ gb->snd_4.signal = (INT8)gb->snd_4.ply_value;
+ }
+
+ if( gb->snd_4.length && gb->snd_4.mode )
+ {
+ gb->snd_4.count++;
+ if( gb->snd_4.count >= gb->snd_4.length )
+ {
+ gb->snd_4.on = 0;
+ gb->snd_regs[NR52] &= 0xF7;
+ }
+ }
+
+ if( gb->snd_4.env_length )
+ {
+ gb->snd_4.env_count++;
+ if( gb->snd_4.env_count >= gb->snd_4.env_length )
+ {
+ gb->snd_4.env_count = 0;
+ gb->snd_4.env_value += gb->snd_4.env_direction;
+ if( gb->snd_4.env_value < 0 )
+ gb->snd_4.env_value = 0;
+ if( gb->snd_4.env_value > 15 )
+ gb->snd_4.env_value = 15;
+ }
+ }
+
+ if( gb->snd_control.mode4_left )
+ left += sample;
+ if( gb->snd_control.mode4_right )
+ right += sample;
+ }
+
+ /* Adjust for master volume */
+ left *= gb->snd_control.vol_left;
+ right *= gb->snd_control.vol_right;
+
+ /* pump up the volume */
+ left <<= 6;
+ right <<= 6;
+
+ /* Update the buffers */
+ *(outputs[0]++) = left;
+ *(outputs[1]++) = right;
+ }
+
+ gb->snd_regs[NR52] = (gb->snd_regs[NR52]&0xf0) | gb->snd_1.on | (gb->snd_2.on << 1) | (gb->snd_3.on << 2) | (gb->snd_4.on << 3);
+}
+
+
+static DEVICE_START( gameboy_sound )
+{
+ gb_sound_t *gb = get_token(device);
+ int I, J;
+
+ memset(&gb->snd_1, 0, sizeof(gb->snd_1));
+ memset(&gb->snd_2, 0, sizeof(gb->snd_2));
+ memset(&gb->snd_3, 0, sizeof(gb->snd_3));
+ memset(&gb->snd_4, 0, sizeof(gb->snd_4));
+
+ gb->channel = device->machine().sound().stream_alloc(*device, 0, 2, device->machine().sample_rate(), 0, gameboy_update);
+ gb->rate = device->machine().sample_rate();
+
+ /* Calculate the envelope and sweep tables */
+ for( I = 0; I < 8; I++ )
+ {
+ gb->env_length_table[I] = (I * ((1 << FIXED_POINT) / 64) * gb->rate) >> FIXED_POINT;
+ gb->swp_time_table[I] = (((I << FIXED_POINT) / 128) * gb->rate) >> (FIXED_POINT - 1);
+ }
+
+ /* Calculate the period tables */
+ for( I = 0; I < MAX_FREQUENCIES; I++ )
+ {
+ gb->period_table[I] = ((1 << FIXED_POINT) / (131072 / (2048 - I))) * gb->rate;
+ gb->period_mode3_table[I] = ((1 << FIXED_POINT) / (65536 / (2048 - I))) * gb->rate;
+ }
+ /* Calculate the period table for mode 4 */
+ for( I = 0; I < 8; I++ )
+ {
+ for( J = 0; J < 16; J++ )
+ {
+ /* I is the dividing ratio of frequencies
+ J is the shift clock frequency */
+ gb->period_mode4_table[I][J] = ((1 << FIXED_POINT) / (524288 / ((I == 0)?0.5:I) / (1 << (J + 1)))) * gb->rate;
+ }
+ }
+
+ /* Calculate the length table */
+ for( I = 0; I < 64; I++ )
+ {
+ gb->length_table[I] = ((64 - I) * ((1 << FIXED_POINT)/256) * gb->rate) >> FIXED_POINT;
+ }
+ /* Calculate the length table for mode 3 */
+ for( I = 0; I < 256; I++ )
+ {
+ gb->length_mode3_table[I] = ((256 - I) * ((1 << FIXED_POINT)/256) * gb->rate) >> FIXED_POINT;
+ }
+
+ gb_sound_w_internal( device, NR52, 0x00 );
+ gb->snd_regs[AUD3W0] = 0xac;
+ gb->snd_regs[AUD3W1] = 0xdd;
+ gb->snd_regs[AUD3W2] = 0xda;
+ gb->snd_regs[AUD3W3] = 0x48;
+ gb->snd_regs[AUD3W4] = 0x36;
+ gb->snd_regs[AUD3W5] = 0x02;
+ gb->snd_regs[AUD3W6] = 0xcf;
+ gb->snd_regs[AUD3W7] = 0x16;
+ gb->snd_regs[AUD3W8] = 0x2c;
+ gb->snd_regs[AUD3W9] = 0x04;
+ gb->snd_regs[AUD3WA] = 0xe5;
+ gb->snd_regs[AUD3WB] = 0x2c;
+ gb->snd_regs[AUD3WC] = 0xac;
+ gb->snd_regs[AUD3WD] = 0xdd;
+ gb->snd_regs[AUD3WE] = 0xda;
+ gb->snd_regs[AUD3WF] = 0x48;
+}
+
+
+DEVICE_GET_INFO( gameboy_sound )
+{
+ switch (state)
+ {
+ /* --- the following bits of info are returned as 64-bit signed integers --- */
+ case DEVINFO_INT_TOKEN_BYTES: info->i = sizeof(gb_sound_t); break;
+
+ /* --- the following bits of info are returned as pointers to data or functions --- */
+ case DEVINFO_FCT_START: info->start = DEVICE_START_NAME(gameboy_sound); break;
+
+ /* --- the following bits of info are returned as NULL-terminated strings --- */
+ case DEVINFO_STR_NAME: strcpy(info->s, "LR35902"); break;
+ case DEVINFO_STR_SOURCE_FILE: strcpy(info->s, __FILE__); break;
+ }
+}
+
+DEFINE_LEGACY_SOUND_DEVICE(GAMEBOY, gameboy_sound);