// license:BSD-3-Clause // copyright-holders:Derrick Renaud /************************************************************************* audio\skydiver.c *************************************************************************/ #include "emu.h" #include "includes/skydiver.h" #include "sound/discrete.h" /************************************************************************/ /* skydiver Sound System Analog emulation */ /* Jan 2004, Derrick Renaud */ /************************************************************************/ static const discrete_555_desc skydiverWhistl555 = { DISC_555_OUT_SQW | DISC_555_OUT_AC, 5, // B+ voltage of 555 DEFAULT_555_VALUES }; static const discrete_lfsr_desc skydiver_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 */ DISC_LFSR_FLAG_OUT_INVERT, /* Output is inverted, Active Low Reset */ 15 /* Output bit */ }; /* Nodes - Sounds */ #define SKYDIVER_NOTE_SND NODE_11 #define SKYDIVER_NOISE_SND NODE_12 #define SKYDIVER_WHISTLE1_SND NODE_13 #define SKYDIVER_WHISTLE2_SND NODE_14 DISCRETE_SOUND_START(skydiver_discrete) /************************************************/ /* skydiver Effects Relative Gain Table */ /* */ /* Effect V-ampIn Gain ratio Relative */ /* Note 3.8 3.8/260.5 1000.0 */ /* Noise 3.8 3.8/680 383.1 */ /* Whistle 5.0 5.0/1500 228.5 */ /************************************************/ /************************************************/ /* Input register mapping for skydiver */ /************************************************/ /* NODE GAIN OFFSET INIT */ DISCRETE_INPUT_DATA (SKYDIVER_RANGE_DATA) DISCRETE_INPUT_LOGIC (SKYDIVER_RANGE3_EN) DISCRETE_INPUT_DATA (SKYDIVER_NOTE_DATA) DISCRETE_INPUTX_DATA (SKYDIVER_NOISE_DATA, 383.1/15.0, 0.0, 0.0) DISCRETE_INPUT_NOT (SKYDIVER_NOISE_RST) DISCRETE_INPUT_LOGIC (SKYDIVER_WHISTLE1_EN) DISCRETE_INPUT_LOGIC (SKYDIVER_WHISTLE2_EN) DISCRETE_INPUT_LOGIC (SKYDIVER_OCT1_EN) DISCRETE_INPUT_LOGIC (SKYDIVER_OCT2_EN) DISCRETE_INPUT_LOGIC (SKYDIVER_SOUND_EN) /************************************************/ /************************************************/ /* The note generator has a selectable range */ /* and selectable frequency. */ /* The base frequency is */ /* 12.096MHz / 2 / range / note freq / 2 */ /* The final /2 is just to give a 50% duty, */ /* so we can just start by 12.096MHz/4/range */ /* The octave is selected by 3 bits selecting */ /* 000 64H = 12096MHz / 2 / 128 */ /* 001 32H = 12096MHz / 2 / 64 */ /* 010 16H = 12096MHz / 2 / 32 */ /* 011 8H = 12096MHz / 2 / 16 */ /* 100 4H = 12096MHz / 2 / 8 */ /* 101 2H = 12096MHz / 2 / 4 */ /* 110 1H = 12096MHz / 2 / 2 */ /* 111 6MHz = 12096MHz / 2 / 1 */ /* We will convert the 3 range bits to a */ /* divide value in the driver before sending */ /* to the sound interface. */ /* */ /* note data: 0xff = off, */ /* 0xfe = /2, */ /* 0x00 = /256 */ /* We will send the note data bit inverted to */ /* sound interface so it is easier to work with.*/ /* */ /* The note generator is disabled by a low on */ /* RANGE3. */ /************************************************/ // We will disable the divide if SKYDIVER_RANGE_DATA = 0 DISCRETE_DIVIDE(NODE_20, SKYDIVER_RANGE_DATA, 12096000.0 /2.0 / 2.0, SKYDIVER_RANGE_DATA) DISCRETE_ADDER2(NODE_21, 1, SKYDIVER_NOTE_DATA, 1) // We will disable the divide if SKYDIVER_NOTE_DATA = 0 DISCRETE_DIVIDE(NODE_22, SKYDIVER_NOTE_DATA, NODE_20, NODE_21) // freq DISCRETE_SQUAREWAVE(SKYDIVER_NOTE_SND, SKYDIVER_RANGE3_EN, NODE_22, 1000.0, 50.0, 0, 0.0) /************************************************/ /* Noise circuit is built around a noise */ /* generator built from 2 shift registers that */ /* are clocked by the 1V signal. */ /* 1V = HSYNC/2 */ /* = 15750/2 */ /* Output is binary weighted with 4 bits of */ /* volume. */ /************************************************/ DISCRETE_LFSR_NOISE(SKYDIVER_NOISE_SND, SKYDIVER_NOISE_RST, SKYDIVER_NOISE_RST, 15750.0/2.0, SKYDIVER_NOISE_DATA, 0, 0, &skydiver_lfsr) /************************************************/ /* Whistle circuit is a 555 capacitor charge */ /* waveform. The original game pot varies from */ /* 0-250k, but we are going to limit it because */ /* below 50k the frequency is too high. */ /* When triggered it starts at it's highest */ /* frequency, then decays at the rate set by */ /* a 68k resistor and 22uf capacitor. */ /************************************************/ DISCRETE_ADJUSTMENT(NODE_30, 250000, 50000, DISC_LINADJ, "WHISTLE1") /* R66 */ DISCRETE_MULTADD(NODE_31, SKYDIVER_WHISTLE1_EN, 3.05-0.33, 0.33) DISCRETE_RCDISC2(NODE_32, SKYDIVER_WHISTLE1_EN, NODE_31, 1.0, NODE_31, 68000.0, 2.2e-5) /* CV */ DISCRETE_SWITCH(NODE_33, 1, SKYDIVER_OCT1_EN, 1e-8, 1e-8 + 3.3e-9) /* Cap C73 & C58 */ DISCRETE_555_ASTABLE_CV(NODE_34, SKYDIVER_WHISTLE1_EN, 100000, NODE_30, NODE_33, NODE_32, &skydiverWhistl555) DISCRETE_MULTIPLY(SKYDIVER_WHISTLE1_SND, NODE_34, 228.5/3.3) DISCRETE_ADJUSTMENT(NODE_35, 250000, 50000, DISC_LINADJ, "WHISTLE2") /* R65 */ DISCRETE_MULTADD(NODE_36, SKYDIVER_WHISTLE2_EN, 3.05-0.33, 0.33) DISCRETE_RCDISC2(NODE_37, SKYDIVER_WHISTLE2_EN, NODE_36, 1.0, NODE_36, 68000.0, 2.2e-5) /* CV */ DISCRETE_SWITCH(NODE_38, 1, SKYDIVER_OCT2_EN, 1e-8, 1e-8 + 3.3e-9) /* Cap C72 & C59 */ DISCRETE_555_ASTABLE_CV(NODE_39, SKYDIVER_WHISTLE2_EN, 100000, NODE_35, NODE_38, NODE_37, &skydiverWhistl555) DISCRETE_MULTIPLY(SKYDIVER_WHISTLE2_SND, NODE_39, 228.5/3.3) /************************************************/ /* Final mix and output. */ /************************************************/ DISCRETE_ADDER4(NODE_90, SKYDIVER_SOUND_EN, SKYDIVER_NOTE_SND, SKYDIVER_NOISE_SND, SKYDIVER_WHISTLE1_SND, SKYDIVER_WHISTLE2_SND) DISCRETE_OUTPUT(NODE_90, 65534.0/(1000.0 + 383.1 + 228.5 + 228.5)) DISCRETE_SOUND_END