/* * datasette-sound.c - Sound of a cassette being played by the Datasette * * Written by * Fabrizio Gennari * * 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 "sound.h" #include "datasette.h" #include "datasette-sound.h" #include "maincpu.h" static sound_chip_t datasette_sound; static CLOCK gap_circular_buffer[200]; static const int gap_circular_buffer_size = sizeof(gap_circular_buffer) / sizeof(gap_circular_buffer[0]); static int gap_circular_buffer_start = 0; static int gap_circular_buffer_end = 0; static CLOCK sound_start_maincpu_clk; static char datasette_halfwaves; static char datasette_square_sign = 1; static char last_was_split_in_two = 0; /* resources */ static void datasette_sound_flush_circular_buffer(void) { datasette_sound.chip_enabled = 0; gap_circular_buffer_end = gap_circular_buffer_start; } void datasette_sound_set_halfwaves(char halfwaves) { datasette_halfwaves = halfwaves; } void datasette_sound_add_to_circular_buffer(CLOCK gap) { if (!datasette_sound_emulation) { datasette_sound_flush_circular_buffer(); return; } gap_circular_buffer[gap_circular_buffer_end] = gap; if (datasette_sound.chip_enabled == 0) { sound_start_maincpu_clk = maincpu_clk; datasette_sound.chip_enabled = 1; } gap_circular_buffer_end = (gap_circular_buffer_end + 1) % gap_circular_buffer_size; if (gap_circular_buffer_end == gap_circular_buffer_start) { gap_circular_buffer_start = (gap_circular_buffer_start + 1) % gap_circular_buffer_size; } } static CLOCK datasette_sound_remove_from_circular_buffer( CLOCK max_amount_to_remove, char divide_by_two, char *must_flip) { CLOCK gap = 0; *must_flip = 0; if (gap_circular_buffer_end != gap_circular_buffer_start) { char try_again; do { try_again = 0; gap = gap_circular_buffer[gap_circular_buffer_start]; if (divide_by_two && !last_was_split_in_two) { gap /= 2; } if (gap > max_amount_to_remove) { if (divide_by_two && !last_was_split_in_two) { if (gap_circular_buffer_start == ((gap_circular_buffer_end + 1) % gap_circular_buffer_size)) { gap_circular_buffer_start = (gap_circular_buffer_start + 1) % gap_circular_buffer_size; try_again = 1; continue; } gap_circular_buffer[gap_circular_buffer_start] -= gap; gap_circular_buffer_start = gap_circular_buffer_start ? gap_circular_buffer_start - 1 : gap_circular_buffer_size - 1; gap_circular_buffer[gap_circular_buffer_start] = gap; last_was_split_in_two = 1; } gap = max_amount_to_remove; } else { *must_flip = 1; last_was_split_in_two = 0; } } while (try_again); gap_circular_buffer[gap_circular_buffer_start] -= gap; if (!gap_circular_buffer[gap_circular_buffer_start]) { gap_circular_buffer_start = (gap_circular_buffer_start + 1) % gap_circular_buffer_size; if (gap_circular_buffer_end == gap_circular_buffer_start) { datasette_sound.chip_enabled = 0; } } } return gap; } #ifdef SOUND_SYSTEM_FLOAT /* FIXME */ static int datasette_sound_machine_calculate_samples(sound_t **psid, float *pbuf, int nr, int scc, CLOCK *delta_t) { int i = 0, j, num_samples; CLOCK cycles_to_be_consumed = *delta_t; double factor = (double)cycles_to_be_consumed / nr; char must_flip; if (sound_start_maincpu_clk) { int initial_zero_samples = (cycles_to_be_consumed + sound_start_maincpu_clk - maincpu_clk) / factor; while (i < initial_zero_samples) { pbuf[i++] = 0.0; } cycles_to_be_consumed = maincpu_clk - sound_start_maincpu_clk; sound_start_maincpu_clk = 0; } while (cycles_to_be_consumed) { CLOCK max_amount_to_consume = cycles_to_be_consumed; CLOCK cycles_to_consume_now = datasette_sound_remove_from_circular_buffer(max_amount_to_consume, (datasette_square_sign == 1) && !datasette_halfwaves, &must_flip); if (!cycles_to_consume_now) { break; } cycles_to_be_consumed -= cycles_to_consume_now; if (i < nr) { if (cycles_to_be_consumed == 0) { num_samples = nr - i; } else { num_samples = cycles_to_consume_now / factor; if (((i + num_samples) < (nr - 1)) && ((cycles_to_be_consumed * 1.0) / ((nr - i) - num_samples)) < factor) { num_samples++; } } for (j = 0; j < num_samples; j++) { pbuf[i++] = (datasette_sound_emulation_volume * datasette_square_sign) / 32767.0; } } if (must_flip) { datasette_square_sign = -datasette_square_sign; } } while (i < nr) { pbuf[i++] = 0.0; } return nr; } #else static int datasette_sound_machine_calculate_samples(sound_t **psid, int16_t *pbuf, int nr, int soc, int scc, CLOCK *delta_t) { int i = 0, j, num_samples; CLOCK cycles_to_be_consumed = *delta_t; double factor = (double)cycles_to_be_consumed / nr; char must_flip; if (sound_start_maincpu_clk) { int initial_zero_samples = (cycles_to_be_consumed + sound_start_maincpu_clk - maincpu_clk) / factor; while (i < initial_zero_samples) { pbuf[i++] = 0; } cycles_to_be_consumed = maincpu_clk - sound_start_maincpu_clk; sound_start_maincpu_clk = 0; } while (cycles_to_be_consumed) { CLOCK max_amount_to_consume = cycles_to_be_consumed; CLOCK cycles_to_consume_now = datasette_sound_remove_from_circular_buffer(max_amount_to_consume, (datasette_square_sign == 1) && !datasette_halfwaves, &must_flip); if (!cycles_to_consume_now) { break; } cycles_to_be_consumed -= cycles_to_consume_now; if (i < nr) { if (cycles_to_be_consumed == 0) { num_samples = nr - i; } else { num_samples = cycles_to_consume_now / factor; if (((i + num_samples) < (nr - 1)) && ((cycles_to_be_consumed * 1.0) / ((nr - i) - num_samples)) < factor) { num_samples++; } } for (j = 0; j < num_samples; j++) { pbuf[i++] = datasette_sound_emulation_volume * datasette_square_sign; } } if (must_flip) { datasette_square_sign = -datasette_square_sign; } } while (i < nr) { pbuf[i++] = 0; } return nr; } #endif static int datasette_sound_machine_cycle_based(void) { return 0; } static int datasette_sound_machine_channels(void) { return 1; } #ifdef SOUND_SYSTEM_FLOAT /* stereo mixing placement of the Datasette sound */ static sound_chip_mixing_spec_t datasette_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 /* Datasette sound 'chip', emulates the sound of a tape in the datasette */ static sound_chip_t datasette_sound = { NULL, /* NO sound chip open function */ NULL, /* NO sound chip init function */ NULL, /* NO sound chip close function */ datasette_sound_machine_calculate_samples, /* sound chip calculate samples function */ NULL, /* NO sound chip store function */ NULL, /* NO sound chip read function */ NULL, /* NO sound chip reset function */ datasette_sound_machine_cycle_based, /* sound chip 'is_cycle_based()' function, chip is NOT cycle based */ datasette_sound_machine_channels, /* sound chip 'get_amount_of_channels()' function, sound chip has 1 channel */ #ifdef SOUND_SYSTEM_FLOAT datasette_sound_mixing_spec, /* stereo mixing placement specs */ #endif 0 /* sound chip enabled flag, toggled upon device (de-)activation */ }; void datasette_sound_init(void) { sound_chip_register(&datasette_sound); }