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Diffstat (limited to 'src/mame/audio/warpwarp.c')
-rw-r--r-- | src/mame/audio/warpwarp.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/src/mame/audio/warpwarp.c b/src/mame/audio/warpwarp.c new file mode 100644 index 00000000000..fc1e4a8c246 --- /dev/null +++ b/src/mame/audio/warpwarp.c @@ -0,0 +1,221 @@ +/**************************************************************************** + * + * warpwarp.c + * + * sound driver + * juergen buchmueller <pullmoll@t-online.de>, jan 2000 + * + ****************************************************************************/ + +#include <math.h> +#include "driver.h" +#include "streams.h" +#include "sound/custom.h" +#include "includes/warpwarp.h" + +#define CLOCK_16H (18432000/3/2/16) +#define CLOCK_1V (18432000/3/2/384) + +static INT16 *decay = NULL; +static sound_stream *channel; +static int sound_latch = 0; +static int music1_latch = 0; +static int music2_latch = 0; +static int sound_signal = 0; +static int sound_volume = 0; +static emu_timer *sound_volume_timer = NULL; +static int music_signal = 0; +static int music_volume = 0; +static emu_timer *music_volume_timer = NULL; +static int noise = 0; + +static TIMER_CALLBACK( sound_volume_decay ) +{ + if( --sound_volume < 0 ) + sound_volume = 0; +} + +WRITE8_HANDLER( warpwarp_sound_w ) +{ + stream_update(channel); + sound_latch = data & 0x0f; + sound_volume = 0x7fff; /* set sound_volume */ + noise = 0x0000; /* reset noise shifter */ + + /* faster decay enabled? */ + if( sound_latch & 8 ) + { + /* + * R85(?) is 10k, Rb is 0, C92 is 1uF + * charge time t1 = 0.693 * (R24 + Rb) * C57 -> 0.22176s + * discharge time t2 = 0.693 * (Rb) * C57 -> 0 + * C90(?) is only charged via D17 (1N914), no discharge! + * Decay: + * discharge C90(?) (1uF) through R13||R14 (22k||47k) + * 0.639 * 15k * 1uF -> 0.9585s + */ + attotime period = attotime_div(attotime_mul(ATTOTIME_IN_HZ(32768), 95850), 100000); + timer_adjust(sound_volume_timer, period, 0, period); + } + else + { + /* + * discharge only after R93 (100k) and through the 10k + * potentiometerin the amplifier section. + * 0.639 * 110k * 1uF -> 7.0290s + * ...but this is not very realistic for the game sound :( + * maybe there _is_ a discharge through the diode D17? + */ +// attotime period = attotime_div(attotime_mul(ATTOTIME_IN_HZ(32768), 702900), 100000); + attotime period = attotime_div(attotime_mul(ATTOTIME_IN_HZ(32768), 191700), 100000); + timer_adjust(sound_volume_timer, period, 0, period); + } +} + +WRITE8_HANDLER( warpwarp_music1_w ) +{ + stream_update(channel); + music1_latch = data & 0x3f; +} + +static TIMER_CALLBACK( music_volume_decay ) +{ + if( --music_volume < 0 ) + music_volume = 0; +} + +WRITE8_HANDLER( warpwarp_music2_w ) +{ + stream_update(channel); + music2_latch = data & 0x3f; + music_volume = 0x7fff; + /* fast decay enabled? */ + if( music2_latch & 0x10 ) + { + /* + * Ra (R83?) is 10k, Rb is 0, C92 is 1uF + * charge time t1 = 0.693 * (Ra + Rb) * C -> 0.22176s + * discharge time is (nearly) zero, because Rb is zero + * C95(?) is only charged via D17, not discharged! + * Decay: + * discharge C95(?) (10uF) through R13||R14 (22k||47k) + * 0.639 * 15k * 10uF -> 9.585s + * ...I'm sure this is off by one number of magnitude :/ + */ + attotime period = attotime_div(attotime_mul(ATTOTIME_IN_HZ(32768), 95850), 100000); + timer_adjust(music_volume_timer, period, 0, period); + } + else + { + /* + * discharge through R14 (47k), + * discharge C95(?) (10uF) through R14 (47k) + * 0.639 * 47k * 10uF -> 30.033s + */ +// attotime period = attotime_div(attotime_mul(ATTOTIME_IN_HZ(32768), 3003300), 100000); + attotime period = attotime_div(attotime_mul(ATTOTIME_IN_HZ(32768), 300330), 100000); + timer_adjust(music_volume_timer, period, 0, period); + } + +} + +static void warpwarp_sound_update(void *param, stream_sample_t **inputs, stream_sample_t **outputs, int length) +{ + static int vcarry = 0; + static int vcount = 0; + static int mcarry = 0; + static int mcount = 0; + stream_sample_t *buffer = outputs[0]; + + while (length--) + { + *buffer++ = (sound_signal + music_signal) / 2; + + /* + * The music signal is selected at a rate of 2H (1.536MHz) from the + * four bits of a 4 bit binary counter which is clocked with 16H, + * which is 192kHz, and is divided by 4 times (64 - music1_latch). + * 0 = 256 steps -> 750 Hz + * 1 = 252 steps -> 761.9 Hz + * ... + * 32 = 128 steps -> 1500 Hz + * ... + * 48 = 64 steps -> 3000 Hz + * ... + * 63 = 4 steps -> 48 kHz + */ + mcarry -= CLOCK_16H / (4 * (64 - music1_latch)); + while( mcarry < 0 ) + { + mcarry += CLOCK_16H; + mcount++; + music_signal = (mcount & ~music2_latch & 15) ? decay[music_volume] : 0; + /* override by noise gate? */ + if( (music2_latch & 32) && (noise & 0x8000) ) + music_signal = decay[music_volume]; + } + + /* clock 1V = 8kHz */ + vcarry -= CLOCK_1V; + while (vcarry < 0) + { + vcarry += CLOCK_16H; + vcount++; + + /* noise is clocked with raising edge of 2V */ + if ((vcount & 3) == 2) + { + /* bit0 = bit0 ^ !bit10 */ + if ((noise & 1) == ((noise >> 10) & 1)) + noise = (noise << 1) | 1; + else + noise = noise << 1; + } + + switch (sound_latch & 7) + { + case 0: /* 4V */ + sound_signal = (vcount & 0x04) ? decay[sound_volume] : 0; + break; + case 1: /* 8V */ + sound_signal = (vcount & 0x08) ? decay[sound_volume] : 0; + break; + case 2: /* 16V */ + sound_signal = (vcount & 0x10) ? decay[sound_volume] : 0; + break; + case 3: /* 32V */ + sound_signal = (vcount & 0x20) ? decay[sound_volume] : 0; + break; + case 4: /* TONE1 */ + sound_signal = !(vcount & 0x01) && !(vcount & 0x10) ? decay[sound_volume] : 0; + break; + case 5: /* TONE2 */ + sound_signal = !(vcount & 0x02) && !(vcount & 0x20) ? decay[sound_volume] : 0; + break; + case 6: /* TONE3 */ + sound_signal = !(vcount & 0x04) && !(vcount & 0x40) ? decay[sound_volume] : 0; + break; + default: /* NOISE */ + /* QH of 74164 #4V */ + sound_signal = (noise & 0x8000) ? decay[sound_volume] : 0; + } + + } + } +} + +void *warpwarp_sh_start(int clock, const struct CustomSound_interface *config) +{ + int i; + + decay = (INT16 *) auto_malloc(32768 * sizeof(INT16)); + + for( i = 0; i < 0x8000; i++ ) + decay[0x7fff-i] = (INT16) (0x7fff/exp(1.0*i/4096)); + + channel = stream_create(0, 1, CLOCK_16H, NULL, warpwarp_sound_update); + + sound_volume_timer = timer_alloc(sound_volume_decay); + music_volume_timer = timer_alloc(music_volume_decay); + return auto_malloc(1); +} |