/* * vic20sound.c - Implementation of VIC20 sound code. * * Written by * Rami Rasanen * Ville-Matias Heikkila * * This file is part of VICE, the Versatile Commodore Emulator. * See README for copyright notice. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA * 02111-1307 USA. * */ #include "vice.h" #include #include #include #include "fastsid.h" #include "lib.h" #include "machine.h" #include "maincpu.h" #include "sid.h" #include "sidcart.h" #include "sid-resources.h" #include "sound.h" #include "types.h" #include "vic20sound.h" #include "vic20.h" /* ---------------------------------------------------------------------*/ /* Some prototypes are needed */ static int vic_sound_machine_init(sound_t *psid, int speed, int cycles_per_sec); static void vic_sound_machine_store(sound_t *psid, uint16_t addr, uint8_t value); #ifdef SOUND_SYSTEM_FLOAT static int vic_sound_machine_calculate_samples(sound_t **psid, float *pbuf, int nr, int sound_chip_channels, CLOCK *delta_t); #else static int vic_sound_machine_calculate_samples(sound_t **psid, int16_t *pbuf, int nr, int sound_output_channels, int sound_chip_channels, CLOCK *delta_t); #endif static int vic_sound_machine_cycle_based(void) { return 1; } static int vic_sound_machine_channels(void) { return 1; } #ifdef SOUND_SYSTEM_FLOAT /* stereo mixing placement of the VIC20 VIC sound */ static sound_chip_mixing_spec_t vic_sound_mixing_spec[SOUND_CHIP_CHANNELS_MAX] = { { 100, /* left channel volume % in case of stereo output, default output to both */ 100 /* right channel volume % in case of stereo output, default output to both */ } }; #endif /* VIC20 VIC sound device */ static sound_chip_t vic_sound_chip = { NULL, /* NO sound chip open function */ vic_sound_machine_init, /* sound chip init function */ NULL, /* NO sound chip close function */ vic_sound_machine_calculate_samples, /* sound chip calculate samples function */ vic_sound_machine_store, /* sound chip store function */ NULL, /* NO sound chip read function */ vic_sound_reset, /* sound chip reset function */ vic_sound_machine_cycle_based, /* sound chip 'is_cycle_based()' function, chip is NOT cycle based */ vic_sound_machine_channels, /* sound chip 'get_amount_of_channels()' function, sound chip has 1 channel */ #ifdef SOUND_SYSTEM_FLOAT vic_sound_mixing_spec, /* stereo mixing placement specs */ #endif 1 /* sound chip enabled flag, chip is always enabled */ }; static uint16_t vic_sound_chip_offset = 0; void vic_sound_chip_init(void) { vic_sound_chip_offset = sound_chip_register(&vic_sound_chip); } /* ---------------------------------------------------------------------*/ /* TODO: remove when new vic_sound_clock is confirmed to work right */ #if 0 static uint8_t noisepattern[1024] = { 7, 30, 30, 28, 28, 62, 60, 56,120,248,124, 30, 31,143, 7, 7,193,192,224, 241,224,240,227,225,192,224,120,126, 60, 56,224,225,195,195,135,199, 7, 30, 28, 31, 14, 14, 30, 14, 15, 15,195,195,241,225,227,193,227,195,195,252, 60, 30, 15,131,195,193,193,195,195,199,135,135,199, 15, 14, 60,124,120, 60, 60, 60, 56, 62, 28,124, 30, 60, 15, 14, 62,120,240,240,224,225,241,193,195,199, 195,225,241,224,225,240,241,227,192,240,224,248,112,227,135,135,192,240,224, 241,225,225,199,131,135,131,143,135,135,199,131,195,131,195,241,225,195,199, 129,207,135, 3,135,199,199,135,131,225,195, 7,195,135,135, 7,135,195,135, 131,225,195,199,195,135,135,143, 15,135,135, 15,207, 31,135,142, 14, 7,129, 195,227,193,224,240,224,227,131,135, 7,135,142, 30, 15, 7,135,143, 31, 7, 135,193,240,225,225,227,199, 15, 3,143,135, 14, 30, 30, 15,135,135, 15,135, 31, 15,195,195,240,248,240,112,241,240,240,225,240,224,120,124,120,124,112, 113,225,225,195,195,199,135, 28, 60, 60, 28, 60,124, 30, 30, 30, 28, 60,120, 248,248,225,195,135, 30, 30, 60, 62, 15, 15,135, 31,142, 15, 15,142, 30, 30, 30, 30, 15, 15,143,135,135,195,131,193,225,195,193,195,199,143, 15, 15, 15, 15,131,199,195,193,225,224,248, 62, 60, 60, 60, 60, 60,120, 62, 30, 30, 30, 15, 15, 15, 30, 14, 30, 30, 15, 15,135, 31,135,135, 28, 62, 31, 15, 15,142, 62, 14, 62, 30, 28, 60,124,252, 56,120,120, 56,120,112,248,124, 30, 60, 60, 48,241,240,112,112,224,248,240,248,120,120,113,225,240,227,193,240,113,227, 199,135,142, 62, 14, 30, 62, 15, 7,135, 12, 62, 15,135, 15, 30, 60, 60, 56, 120,241,231,195,195,199,142, 60, 56,240,224,126, 30, 62, 14, 15, 15, 15, 3, 195,195,199,135, 31, 14, 30, 28, 60, 60, 15, 7, 7,199,199,135,135,143, 15, 192,240,248, 96,240,240,225,227,227,195,195,195,135, 15,135,142, 30, 30, 63, 30, 14, 28, 60,126, 30, 60, 56,120,120,120, 56,120, 60,225,227,143, 31, 28, 120,112,126, 15,135, 7,195,199, 15, 30, 60, 14, 15, 14, 30, 3,240,240,241, 227,193,199,192,225,225,225,225,224,112,225,240,120,112,227,199, 15,193,225, 227,195,192,240,252, 28, 60,112,248,112,248,120, 60,112,240,120,112,124,124, 60, 56, 30, 62, 60,126, 7,131,199,193,193,225,195,195,195,225,225,240,120, 124, 62, 15, 31, 7,143, 15,131,135,193,227,227,195,195,225,240,248,240, 60, 124, 60, 15,142, 14, 31, 31, 14, 60, 56,120,112,112,240,240,248,112,112,120, 56, 60,112,224,240,120,241,240,120, 62, 60, 15, 7, 14, 62, 30, 63, 30, 14, 15,135,135, 7, 15, 7,199,143, 15,135, 30, 30, 31, 30, 30, 60, 30, 28, 62, 15, 3,195,129,224,240,252, 56, 60, 62, 14, 30, 28,124, 30, 31, 14, 62, 28, 120,120,124, 30, 62, 30, 60, 31, 15, 31, 15, 15,143, 28, 60,120,248,240,248, 112,240,120,120, 60, 60,120, 60, 31, 15, 7,134, 28, 30, 28, 30, 30, 31, 3, 195,199,142, 60, 60, 28, 24,240,225,195,225,193,225,227,195,195,227,195,131, 135,131,135, 15, 7, 7,225,225,224,124,120, 56,120,120, 60, 31, 15,143, 14, 7, 15, 7,131,195,195,129,240,248,241,224,227,199, 28, 62, 30, 15, 15,195, 240,240,227,131,195,199, 7, 15, 15, 15, 15, 15, 7,135, 15, 15, 14, 15, 15, 30, 15, 15,135,135,135,143,199,199,131,131,195,199,143,135, 7,195,142, 30, 56, 62, 60, 56,124, 31, 28, 56, 60,120,124, 30, 28, 60, 63, 30, 14, 62, 28, 60, 31, 15, 7,195,227,131,135,129,193,227,207, 14, 15, 30, 62, 30, 31, 15, 143,195,135, 14, 3,240,240,112,224,225,225,199,142, 15, 15, 30, 14, 30, 31, 28,120,240,241,241,224,241,225,225,224,224,241,193,240,113,225,195,131,199, 131,225,225,248,112,240,240,240,240,240,112,248,112,112, 97,224,240,225,224, 120,113,224,240,248, 56, 30, 28, 56,112,248, 96,120, 56, 60, 63, 31, 15, 31, 15, 31,135,135,131,135,131,225,225,240,120,241,240,112, 56, 56,112,224,227, 192,224,248,120,120,248, 56,241,225,225,195,135,135, 14, 30, 31, 14, 14, 15, 15,135,195,135, 7,131,192,240, 56, 60, 60, 56,240,252, 62, 30, 28, 28, 56, 112,240,241,224,240,224,224,241,227,224,225,240,240,120,124,120, 60,120,120, 56,120,120,120,120,112,227,131,131,224,195,193,225,193,193,193,227,195,199, 30, 14, 31, 30, 30, 15, 15, 14, 14, 14, 7,131,135,135, 14, 7,143, 15, 15, 15, 14, 28,112,225,224,113,193,131,131,135, 15, 30, 24,120,120,124, 62, 28, 56,240,225,224,120,112, 56, 60, 62, 30, 60, 30, 28,112, 60, 56, 63 }; #endif static float voltagefunction[] = { 0.00f, 148.28f, 296.55f, 735.97f, 914.88f, 1126.89f, 1321.86f, 1503.07f, 1603.50f, 1758.00f, 1913.98f, 2070.94f, 2220.36f, 2342.91f, 2488.07f, 3188.98f, 3285.76f, 3382.53f, 3479.31f, 3576.08f, 3672.86f, 3769.63f, 3866.41f, 3963.18f, 4059.96f, 4248.10f, 4436.24f, 4624.38f, 4812.53f, 5000.67f, 5188.81f, 5192.91f, 5197.00f, 5338.52f, 5480.04f, 5621.56f, 5763.07f, 5904.59f, 6046.11f, 6187.62f, 6329.14f, 6609.31f, 6889.47f, 7169.64f, 7449.80f, 7729.97f, 7809.36f, 7888.75f, 7968.13f, 8047.52f, 8126.91f, 8206.30f, 8285.69f, 8365.07f, 8444.46f, 8523.85f, 8603.24f, 8905.93f, 9208.63f, 9511.32f, 9814.02f, 9832.86f, 9851.70f, 9870.54f, 9889.38f, 9908.22f, 9927.07f, 9945.91f, 9964.75f, 9983.59f, 10002.43f, 10021.27f, 10040.12f, 10787.23f, 11534.34f, 12281.45f, 12284.98f, 12288.50f, 12292.03f, 12295.56f, 12299.09f, 12302.62f, 12306.15f, 12309.68f, 12313.21f, 12316.74f, 12320.26f, 12323.79f, 12327.32f, 13113.05f, 13898.78f, 13910.58f, 13922.39f, 13934.19f, 13945.99f, 13957.80f, 13969.60f, 13981.40f, 13993.21f, 14005.01f, 14016.81f, 14028.62f, 14040.42f, 14052.22f, 14064.03f, 16926.31f, 16987.04f, 17047.77f, 17108.50f, 17169.23f, 17229.96f, 17290.69f, 17351.42f, 17412.15f, 17472.88f, 17533.61f, 17594.34f, 17655.07f, 17715.80f, 17776.53f, 17837.26f, 18041.51f, 18245.77f, 18450.02f, 18654.28f, 18858.53f, 19062.78f, 19267.04f, 19471.29f, 19675.55f, 19879.80f, 20084.05f, 20288.31f, 20417.74f, 20547.17f, 20676.61f, 20774.26f, 20871.91f, 20969.55f, 21067.20f, 21164.85f, 21262.50f, 21360.15f, 21457.80f, 21555.45f, 21653.09f, 21750.74f, 21848.39f, 21946.04f, 22043.69f, 22141.34f, 22212.33f, 22283.33f, 22354.33f, 22425.33f, 22496.32f, 22567.32f, 22638.32f, 22709.32f, 22780.31f, 22851.31f, 22922.31f, 22993.31f, 23064.30f, 23135.30f, 23206.30f, 23255.45f, 23304.60f, 23353.75f, 23402.91f, 23452.06f, 23501.21f, 23550.36f, 23599.51f, 23648.67f, 23768.81f, 23888.96f, 24009.11f, 24129.26f, 24249.41f, 24369.56f, 24451.92f, 24534.28f, 24616.63f, 24698.99f, 24781.35f, 24863.70f, 24946.06f, 25028.42f, 25110.77f, 25193.13f, 25275.49f, 25357.84f, 25440.20f, 25522.56f, 25604.92f, 25658.87f, 25712.83f, 25766.79f, 25820.75f, 25874.71f, 25928.66f, 25982.62f, 26036.58f, 26090.54f, 26144.49f, 26198.45f, 26252.41f, 26306.37f, 26360.33f, 26414.28f, 26501.23f, 26588.17f, 26675.12f, 26762.06f, 26849.01f, 26935.95f, 27022.90f, 27109.84f, 27196.78f, 27283.73f, 27370.67f, 27457.62f, 27544.56f, 27631.51f, 27718.45f, 27726.89f, 27735.33f, 27743.78f, 27752.22f, 27760.66f, 27769.10f, 27777.54f, 27785.98f, 27794.43f, 27802.87f, 27811.31f, 27819.75f, 27828.19f, 27836.63f, 27845.08f, 27853.52f, 27861.96f, 27870.40f, 27878.84f, 27887.28f, 27895.73f, 27904.17f, 27912.61f, 27921.05f, 27929.49f, 27937.93f, 27946.38f, 27954.82f, 27963.26f, 27971.70f, 27980.14f, 27988.58f, 27997.03f, 28005.47f, 28013.91f, 28022.35f, 28030.79f, 28039.23f, 28047.68f, 28056.12f, 28064.56f, 28073.00f, 28081.44f, 28089.88f, 28098.33f, 28106.77f, 28115.21f, 28123.65f, 28132.09f, 28140.53f, 28148.98f, 28157.42f, 28165.86f, 28174.30f, 28182.74f, 28191.18f, 28199.63f, 28208.07f, 28216.51f, 28224.95f, 28233.39f, 28241.83f, 28250.28f, 28258.72f, 28267.16f, 28275.60f, 28284.04f, 28292.48f, 28300.93f, 28309.37f, 28317.81f, 28326.25f, 28334.69f, 28343.13f, 28351.58f, 28360.02f, 28368.46f, 28376.90f, 28385.34f, 28393.78f, 28402.23f, 28410.67f, 28419.11f, 28427.55f, 28435.99f, 28444.43f, 28452.88f, 28461.32f, 28469.76f, 28478.20f, 28486.64f, 28495.08f, 28503.53f, 28511.97f, 28520.41f, 28528.85f, 28537.29f, 28545.73f, 28554.18f, 28562.62f, 28571.06f, 28579.50f, 28587.94f, 28596.38f, 28604.83f, 28613.27f, 28621.71f, 28630.15f, 28638.59f, 28647.03f, 28655.48f, 28663.92f, 28672.36f, 28680.80f, 28689.24f, 28697.68f, 28706.13f, 28714.57f, 28723.01f, 28731.45f, 28739.89f, 28748.33f, 28756.78f, 28765.22f, 28773.66f, 28782.10f, 28790.54f, 28798.98f, 28807.43f, 28815.87f, 28824.31f, 28832.75f, 28841.19f, 28849.63f, 28858.08f, 28866.52f, 28874.96f, 28883.40f, 28891.84f, 28900.28f, 28908.73f, 28917.17f, 28925.61f, 28934.05f, 28942.49f, 28950.93f, 28959.38f, 28967.82f, 28976.26f, 28984.70f, 28993.14f, 29001.58f, 29010.03f, 29018.47f, 29026.91f, 29035.35f, 29043.79f, 29052.23f, 29060.68f, 29069.12f, 29077.56f, 29086.00f, 29094.44f, 29102.88f, 29111.33f, 29119.77f, 29128.21f, 29136.65f, 29145.09f, 29153.53f, 29161.98f, 29170.42f, 29178.86f, 29187.30f, 29195.74f, 29204.18f, 29212.63f, 29221.07f, 29229.51f, 29237.95f, 29246.39f, 29254.83f, 29263.28f, 29271.72f, 29280.16f, 29288.60f, 29297.04f, 29305.48f, 29313.93f, 29322.37f, 29330.81f, 29339.25f, 29347.69f, 29356.13f, 29364.58f, 29373.02f, 29381.46f, 29389.90f, 29398.34f, 29406.78f, 29415.23f, 29423.67f, 29432.11f, 29440.55f, 29448.99f, 29457.43f, 29465.88f, 29474.32f, 29482.76f, 29491.20f }; static uint8_t vic20_sound_data[16]; /* dummy function for now */ int machine_sid2_check_range(unsigned int sid_adr) { return 0; } /* dummy function for now */ int machine_sid3_check_range(unsigned int sid_adr) { return 0; } /* dummy function for now */ int machine_sid4_check_range(unsigned int sid_adr) { return 0; } /* dummy function for now */ int machine_sid5_check_range(unsigned int sid_adr) { return 0; } /* dummy function for now */ int machine_sid6_check_range(unsigned int sid_adr) { return 0; } /* dummy function for now */ int machine_sid7_check_range(unsigned int sid_adr) { return 0; } /* dummy function for now */ int machine_sid8_check_range(unsigned int sid_adr) { return 0; } void machine_sid2_enable(int val) { } struct sound_vic20_s { unsigned char div; struct { unsigned char out; unsigned char reg; unsigned char shift; signed short ctr; } ch[4]; unsigned short noisectr; unsigned char volume; int cyclecount; int accum; int accum_cycles; float cycles_per_sample; float leftover_cycles; int speed; float highpassbuf; float highpassbeta; float lowpassbuf; float lowpassbeta; }; typedef struct sound_vic20_s sound_vic20_t; static struct sound_vic20_s snd; void vic_sound_clock(CLOCK cycles); #ifdef SOUND_SYSTEM_FLOAT /* FIXME */ static int vic_sound_machine_calculate_samples(sound_t **psid, float *pbuf, int nr, int scc, CLOCK *delta_t) { int s = 0; float o; int samples_to_do; while (s < nr && *delta_t >= snd.cycles_per_sample - snd.leftover_cycles) { samples_to_do = (int)(snd.cycles_per_sample - snd.leftover_cycles); snd.leftover_cycles += samples_to_do - snd.cycles_per_sample; vic_sound_clock(samples_to_do); o = (snd.lowpassbuf - snd.highpassbuf) / 32767.0; snd.highpassbuf += snd.highpassbeta * (snd.lowpassbuf - snd.highpassbuf); snd.lowpassbuf += snd.lowpassbeta * (voltagefunction[(((snd.accum * 7) / snd.accum_cycles) + 1) * snd.volume] - snd.lowpassbuf); pbuf[s] = o; s++; snd.accum = 0; snd.accum_cycles = 0; *delta_t -= samples_to_do; } if (*delta_t > 0) { snd.leftover_cycles += *delta_t; vic_sound_clock(*delta_t); *delta_t = 0; } return s; } #else static int vic_sound_machine_calculate_samples(sound_t **psid, int16_t *pbuf, int nr, int soc, int scc, CLOCK *delta_t) { int s = 0; int i; float o; int16_t vicbuf; int samples_to_do; while (s < nr && *delta_t >= snd.cycles_per_sample - snd.leftover_cycles) { samples_to_do = (int)(snd.cycles_per_sample - snd.leftover_cycles); snd.leftover_cycles += samples_to_do - snd.cycles_per_sample; vic_sound_clock(samples_to_do); o = snd.lowpassbuf - snd.highpassbuf; snd.highpassbuf += snd.highpassbeta * (snd.lowpassbuf - snd.highpassbuf); snd.lowpassbuf += snd.lowpassbeta * (voltagefunction[(((snd.accum * 7) / snd.accum_cycles) + 1) * snd.volume] - snd.lowpassbuf); if (o < -32768) { vicbuf = -32768; } else if (o > 32767) { vicbuf = 32767; } else { vicbuf = (int16_t)o; } for (i = 0; i < soc; i++) { pbuf[(s * soc) + i] = vicbuf; } s++; snd.accum = 0; snd.accum_cycles = 0; *delta_t -= samples_to_do; } if (*delta_t > 0) { snd.leftover_cycles += *delta_t; vic_sound_clock(*delta_t); *delta_t = 0; } return s; } #endif void vic_sound_reset(sound_t *psid, CLOCK cpu_clk) { uint16_t i; for (i = 10; i < 15; i++) { vic_sound_store(i, 0); } } void vic_sound_store(uint16_t addr, uint8_t value) { addr &= 0x0f; vic20_sound_data[addr] = value; sound_store((uint16_t)(vic_sound_chip_offset | addr), value, 0); } static uint16_t noise_LFSR = 0x0000; static uint8_t noise_LFSR0_old = 0; void vic_sound_clock(CLOCK cycles) { CLOCK i; int j, enabled; if (cycles <= 0) { return; } for (j = 0; j < 4; j++) { int chspeed = "\4\3\2\1"[j]; if (snd.ch[j].ctr > cycles) { snd.accum += snd.ch[j].out * cycles; snd.ch[j].ctr -= cycles; } else { for (i = cycles; i; i--) { snd.ch[j].ctr--; if (snd.ch[j].ctr <= 0) { int a = (~snd.ch[j].reg) & 127; int edge_trigger; a = a ? a : 128; snd.ch[j].ctr += a << chspeed; enabled = (snd.ch[j].reg & 128) >> 7; edge_trigger = (noise_LFSR & 1) & !noise_LFSR0_old; if((j != 3) || ((j == 3) && edge_trigger)) { uint8_t shift = snd.ch[j].shift; shift = ((shift << 1) | (((((shift & 128) >> 7)) ^ 1) & enabled)); snd.ch[j].shift = shift; } if(j == 3) { int bit3 = (noise_LFSR >> 3) & 1; int bit12 = (noise_LFSR >> 12) & 1; int bit14 = (noise_LFSR >> 14) & 1; int bit15 = (noise_LFSR >> 15) & 1; int gate1 = bit3 ^ bit12; int gate2 = bit14 ^ bit15; int gate3 = (gate1 ^ gate2) ^ 1; int gate4 = (gate3 & enabled) ^ 1; noise_LFSR0_old = noise_LFSR & 1; noise_LFSR = (noise_LFSR << 1) | gate4; } snd.ch[j].out = snd.ch[j].shift & (j == 3 ? enabled : 1); } snd.accum += snd.ch[j].out; /* FIXME: doesn't take DC offset into account */ } } } snd.accum_cycles += cycles; } /* TODO: remove when the code above is confirmed to work right */ #if 0 void vic_sound_clock(int cycles) { int i, j; if (cycles <= 0) { return; } for (j = 0; j < 3; j++) { int chspeed = "\4\3\2"[j]; if (snd.ch[j].ctr > cycles) { snd.accum += snd.ch[j].out * cycles; snd.ch[j].ctr -= cycles; } else { for (i = cycles; i; i--) { snd.ch[j].ctr--; if (snd.ch[j].ctr <= 0) { int a = (~snd.ch[j].reg) & 127; a = a ? a : 128; snd.ch[j].ctr += a << chspeed; if (snd.ch[j].reg & 128) { unsigned char shift = snd.ch[j].shift; shift = ((shift << 1) | ((shift & 128) >> 7)) ^ 1; snd.ch[j].shift = shift; snd.ch[j].out = shift & 1; } else { snd.ch[j].shift <<= 1; snd.ch[j].out = 0; } } snd.accum += snd.ch[j].out; } } } if (snd.ch[3].ctr > cycles) { snd.accum += snd.ch[3].out * cycles; snd.ch[3].ctr -= cycles; } else { for (i = cycles; i; i--) { snd.ch[3].ctr--; if (snd.ch[3].ctr <= 0) { int a = (~snd.ch[3].reg) & 127; a = a ? a : 128; snd.ch[3].ctr += a << 4; if (snd.ch[3].reg & 128) { snd.ch[3].out = (noisepattern[(snd.noisectr >> 3) & 1023] >> (snd.noisectr & 7)) & 1; } else { snd.ch[3].out = 0; } snd.noisectr++; } snd.accum += snd.ch[3].out; } } snd.accum_cycles += cycles; } #endif static void vic_sound_machine_store(sound_t *psid, uint16_t addr, uint8_t value) { switch (addr) { case 0xA: snd.ch[0].reg = value; break; case 0xB: snd.ch[1].reg = value; break; case 0xC: snd.ch[2].reg = value; break; case 0xD: snd.ch[3].reg = value; break; case 0xE: snd.volume = value & 0x0f; break; } } static int vic_sound_machine_init(sound_t *psid, int speed, int cycles_per_sec) { uint32_t i; float dt; memset((unsigned char*)&snd, 0, sizeof(snd)); snd.cycles_per_sample = (float)cycles_per_sec / speed; snd.leftover_cycles = 0.0f; snd.lowpassbuf = 0.0f; snd.highpassbuf = 0.0f; snd.speed = speed; dt = 1.f / speed; /* Audio output stage 5V -----+ audio| 1k | +---+---R---+--------(K) +----- out | | | | |audio -----+ C .01 C .1 | 1 uF | | uF | uF +-----C-----+ 1K | | GND GND R 470 | amp | +----- GND */ /* Low-pass: R = 1 kOhm, C = 100 nF; RC = 1e3*1e-7 = 1e-4 (1591 Hz) */ snd.lowpassbeta = dt / ( dt + 1e-4f ); /* High-pass: R = 1 kOhm, C = 1 uF; RC = 1e3*1e-6 = 1e-3 ( 159 Hz) */ snd.highpassbeta = dt / ( dt + 1e-3f ); for (i = 0; i < 16; i++) { vic_sound_machine_store(psid, (uint16_t)i, vic20_sound_data[i]); } return 1; } char *sound_machine_dump_state(sound_t *psid) { return sid_sound_machine_dump_state(psid); } void sound_machine_enable(int enable) { sid_sound_machine_enable(enable); }