// license:BSD-3-Clause
// copyright-holders:Mike Balfour
/*************************************************************************
audio\bsktball.c
*************************************************************************/
#include "emu.h"
#include "includes/bsktball.h"
#include "sound/discrete.h"
/***************************************************************************
Sound handlers
***************************************************************************/
WRITE8_MEMBER(bsktball_state::bsktball_bounce_w)
{
m_discrete->write(space, BSKTBALL_CROWD_DATA, data & 0x0f); // Crowd
m_discrete->write(space, BSKTBALL_BOUNCE_EN, data & 0x10); // Bounce
}
WRITE8_MEMBER(bsktball_state::bsktball_note_w)
{
m_discrete->write(space, BSKTBALL_NOTE_DATA, data); // Note
}
/************************************************************************/
/* bsktball Sound System Analog emulation */
/************************************************************************/
static const discrete_lfsr_desc bsktball_lfsr =
{
DISC_CLK_IS_FREQ,
16, /* Bit Length */
0, /* Reset Value */
0, /* Use Bit 0 as XOR input 0 */
14, /* Use Bit 14 as XOR input 1 */
DISC_LFSR_XNOR, /* Feedback stage1 is XNOR */
DISC_LFSR_OR, /* Feedback stage2 is just stage 1 output OR with external feed */
DISC_LFSR_REPLACE, /* Feedback stage3 replaces the shifted register contents */
0x000001, /* Everything is shifted into the first bit only */
0, /* Output is already inverted by XNOR */
15 /* Output bit */
};
static const discrete_dac_r1_ladder bsktball_crowd_r1_ladder =
{
4,
{RES_K(390), RES_K(220), RES_K(100), RES_K(56)}, // r55, r54, r53, r52
0, 0, // no bias
RES_K(1), // r21
CAP_U(0.1) // c32
};
static const discrete_op_amp_filt_info bsktball_crowd_filt =
{
1.0/(1.0/RES_K(390) + 1.0/RES_K(220) + 1.0/RES_K(100) + 1.0/RES_K(56) + 1.0/RES_K(1)), // r55, r54, r53, r52, r21
0, 0, 0,
RES_K(330), // r58
CAP_U(.01), // c55
CAP_U(.022), // c56
0,
5, 12, 0
};
static const discrete_mixer_desc bsktball_mixer =
{
DISC_MIXER_IS_OP_AMP,
{RES_K(47), RES_K(47), RES_K(220)}, // r56, r57, r60
{0}, // no rNodes
{CAP_U(.01), CAP_U(.01), CAP_U(.01)}, // c53, c54, c57
0,
RES_K(47), // r61
CAP_U(.001), // c58
CAP_U(1),
5,
7500
};
#define BSKTBALL_32H 12096000.0/4/32
#define BSKTBALL_256H 12096000.0/768
/* Nodes - Sounds */
#define BSKTBALL_NOISE NODE_10
#define BSKTBALL_BOUNCE_SND BSKTBALL_BOUNCE_EN
#define BSKTBALL_NOTE_SND NODE_12
#define BSKTBALL_CROWD_SND NODE_13
DISCRETE_SOUND_START(bsktball_discrete)
/************************************************/
/* Input register mapping for bsktball */
/************************************************/
/* NODE GAIN OFFSET INIT */
DISCRETE_INPUT_DATA (BSKTBALL_NOTE_DATA)
DISCRETE_INPUT_DATA (BSKTBALL_CROWD_DATA)
/* Bounce is a trigger fed directly to the amp */
DISCRETE_INPUTX_LOGIC(BSKTBALL_BOUNCE_EN, DEFAULT_TTL_V_LOGIC_1, 0, 0.0)
DISCRETE_INPUT_NOT (BSKTBALL_NOISE_EN)
/************************************************/
/* Crowd effect is variable amplitude, filtered */
/* random noise. */
/* LFSR clk = 256H = 15750.0Hz */
/************************************************/
DISCRETE_LFSR_NOISE(BSKTBALL_NOISE, BSKTBALL_NOISE_EN, BSKTBALL_NOISE_EN, BSKTBALL_256H, 1, 0, .5, &bsktball_lfsr)
DISCRETE_SWITCH(NODE_20, 1, BSKTBALL_NOISE, 0, BSKTBALL_CROWD_DATA) // enable data, gate D11
DISCRETE_DAC_R1(NODE_21, NODE_20, DEFAULT_TTL_V_LOGIC_1, &bsktball_crowd_r1_ladder)
DISCRETE_OP_AMP_FILTER(BSKTBALL_CROWD_SND, 1, NODE_21, 0, DISC_OP_AMP_FILTER_IS_BAND_PASS_1M, &bsktball_crowd_filt)
/************************************************/
/* Note sound is created by a divider circuit. */
/* The master clock is the 32H signal, which is */
/* 12.096MHz/128. This is then sent to a */
/* preloadable 8 bit counter, which loads the */
/* value from OUT30 when overflowing from 0xFF */
/* to 0x00. Therefore it divides by 2 (OUT30 */
/* = FE) to 256 (OUT30 = 00). */
/* There is also a final /2 stage. */
/* Note that there is no music disable line. */
/* When there is no music, the game sets the */
/* oscillator to 0Hz. (OUT30 = FF) */
/************************************************/
DISCRETE_NOTE(NODE_30, 1, BSKTBALL_32H, BSKTBALL_NOTE_DATA, 255, 1, DISC_CLK_IS_FREQ | DISC_OUT_IS_ENERGY)
DISCRETE_GAIN(BSKTBALL_NOTE_SND, NODE_30, DEFAULT_TTL_V_LOGIC_1)
/************************************************/
/* Mixing stage - B11 */
/************************************************/
DISCRETE_MIXER3(NODE_90, 1, BSKTBALL_NOTE_SND, BSKTBALL_BOUNCE_SND, BSKTBALL_CROWD_SND, &bsktball_mixer)
DISCRETE_OUTPUT(NODE_90, 1)
DISCRETE_SOUND_END