// license:BSD-3-Clause
// copyright-holders:Derrick Renaud
/*************************************************************************
audio\orbit.cpp
*************************************************************************/
#include "emu.h"
#include "includes/orbit.h"
/*************************************
*
* Write handlers
*
*************************************/
void orbit_state::note_w(uint8_t data)
{
m_discrete->write(ORBIT_NOTE_FREQ, (~data) & 0xff);
}
void orbit_state::note_amp_w(uint8_t data)
{
m_discrete->write(ORBIT_ANOTE1_AMP, data & 0x0f);
m_discrete->write(ORBIT_ANOTE2_AMP, data >> 4);
}
void orbit_state::noise_amp_w(uint8_t data)
{
m_discrete->write(ORBIT_NOISE1_AMP, data & 0x0f);
m_discrete->write(ORBIT_NOISE2_AMP, data >> 4);
}
void orbit_state::noise_rst_w(uint8_t data)
{
m_discrete->write(ORBIT_NOISE_EN, 0);
}
/************************************************************************/
/* orbit Sound System Analog emulation */
/************************************************************************/
static const discrete_lfsr_desc orbit_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 */
};
/* Nodes - Sounds */
#define ORBIT_NOISE NODE_10
#define ORBIT_NOISE1_SND NODE_11
#define ORBIT_NOISE2_SND NODE_12
#define ORBIT_ANOTE1_SND NODE_13
#define ORBIT_ANOTE2_SND NODE_14
#define ORBIT_WARNING_SND NODE_15
DISCRETE_SOUND_START(orbit_discrete)
/************************************************/
/* orbit Effects Relataive Gain Table */
/* */
/* Effect V-ampIn Gain ratio Relative */
/* Note 3.8 10/(20.1+.47+.55) 962.1 */
/* Warning 3.8 10/(20.1+6.8) 755.4 */
/* Noise 3.8 10/(20.1+.22) 1000.0 */
/************************************************/
/************************************************/
/* Input register mapping for orbit */
/************************************************/
/* NODE GAIN OFFSET INIT */
DISCRETE_INPUT_DATA (ORBIT_NOTE_FREQ)
DISCRETE_INPUTX_DATA(ORBIT_ANOTE1_AMP, 962.1/15, 0, 0.0)
DISCRETE_INPUTX_DATA(ORBIT_ANOTE2_AMP, 962.1/15, 0, 0.0)
DISCRETE_INPUTX_DATA(ORBIT_NOISE1_AMP, 1000.0/15*10, 0, 0.0)
DISCRETE_INPUTX_DATA(ORBIT_NOISE2_AMP, 1000.0/15*10, 0, 0.0)
DISCRETE_INPUT_LOGIC(ORBIT_WARNING_EN)
DISCRETE_INPUT_PULSE(ORBIT_NOISE_EN, 1)
/************************************************/
/* Warning is just a triggered 2V signal */
/************************************************/
DISCRETE_SQUAREWFIX(ORBIT_WARNING_SND, ORBIT_WARNING_EN, 15750.0/4, 755.4, 50.0, 0, 0.0)
/************************************************/
/* Noise effect is variable amplitude, filtered */
/* random noise. */
/* LFSR clk = 32V= 15750.0Hz/2/32 */
/************************************************/
DISCRETE_LFSR_NOISE(ORBIT_NOISE, ORBIT_NOISE_EN, ORBIT_NOISE_EN, 15750.0/2/32, 1, 0, 0, &orbit_lfsr)
DISCRETE_MULTIPLY(NODE_20, ORBIT_NOISE, ORBIT_NOISE1_AMP)
DISCRETE_MULTIPLY(NODE_21, ORBIT_NOISE, ORBIT_NOISE2_AMP)
DISCRETE_FILTER2(ORBIT_NOISE1_SND, 1, NODE_20, 160.0, (1.0 / 10.0), DISC_FILTER_BANDPASS)
DISCRETE_FILTER2(ORBIT_NOISE2_SND, 1, NODE_21, 160.0, (1.0 / 10.0), DISC_FILTER_BANDPASS)
/************************************************/
/* Note sound is created by a divider circuit. */
/* The master clock is the 64H signal, which is */
/* 12.096MHz/256. This is then sent to a */
/* preloadable 8 bit counter, which loads the */
/* value from NOTELD when overflowing from 0xFF */
/* to 0x00. Therefore it divides by 2 (NOTELD */
/* = FE) to 256 (NOTELD = 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. (NOTELD = FF) */
/************************************************/
DISCRETE_ADDER2(NODE_30, 1, ORBIT_NOTE_FREQ, 1) /* To get values of 1 - 256 */
DISCRETE_DIVIDE(NODE_31, 1, 12096000.0/256/2, NODE_30)
DISCRETE_SQUAREWAVE(ORBIT_ANOTE1_SND, ORBIT_NOTE_FREQ, NODE_31, ORBIT_ANOTE1_AMP, 50.0, 0, 0.0) /* NOTE=FF Disables audio */
DISCRETE_SQUAREWAVE(ORBIT_ANOTE2_SND, ORBIT_NOTE_FREQ, NODE_31, ORBIT_ANOTE2_AMP, 50.0, 0, 0.0) /* NOTE=FF Disables audio */
/************************************************/
/* Final mix and output. */
/************************************************/
DISCRETE_ADDER3(NODE_90, 1, ORBIT_WARNING_SND, ORBIT_NOISE1_SND, ORBIT_ANOTE1_SND)
DISCRETE_ADDER3(NODE_91, 1, ORBIT_WARNING_SND, ORBIT_NOISE2_SND, ORBIT_ANOTE2_SND)
DISCRETE_OUTPUT(NODE_90, 65534.0/(962.1+755.4+1000.0))
DISCRETE_OUTPUT(NODE_91, 65534.0/(962.1+755.4+1000.0))
DISCRETE_SOUND_END