diff options
Diffstat (limited to 'src/mame/audio/wiping.c')
-rw-r--r-- | src/mame/audio/wiping.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/src/mame/audio/wiping.c b/src/mame/audio/wiping.c new file mode 100644 index 00000000000..6ca3348fd62 --- /dev/null +++ b/src/mame/audio/wiping.c @@ -0,0 +1,249 @@ +/*************************************************************************** + + Wiping sound driver (quick hack of the Namco sound driver) + + used by wiping.c and clshroad.c + +***************************************************************************/ + +#include "driver.h" +#include "streams.h" +#include "sound/custom.h" + + +/* 8 voices max */ +#define MAX_VOICES 8 + + +static const int samplerate = 48000; +static const int defgain = 48; + + +/* this structure defines the parameters for a channel */ +typedef struct +{ + int frequency; + int counter; + int volume; + const UINT8 *wave; + int oneshot; + int oneshotplaying; +} sound_channel; + + +/* globals available to everyone */ +UINT8 *wiping_soundregs; + +/* data about the sound system */ +static sound_channel channel_list[MAX_VOICES]; +static sound_channel *last_channel; + +/* global sound parameters */ +static const UINT8 *sound_prom,*sound_rom; +static int num_voices; +static int sound_enable; +static sound_stream *stream; + +/* mixer tables and internal buffers */ +static INT16 *mixer_table; +static INT16 *mixer_lookup; +static short *mixer_buffer; +static short *mixer_buffer_2; + + + +/* build a table to divide by the number of voices; gain is specified as gain*16 */ +static int make_mixer_table(int voices, int gain) +{ + int count = voices * 128; + int i; + + /* allocate memory */ + mixer_table = auto_malloc(256 * voices * sizeof(INT16)); + + /* find the middle of the table */ + mixer_lookup = mixer_table + (128 * voices); + + /* fill in the table - 16 bit case */ + for (i = 0; i < count; i++) + { + int val = i * gain * 16 / voices; + if (val > 32767) val = 32767; + mixer_lookup[ i] = val; + mixer_lookup[-i] = -val; + } + + return 0; +} + + +/* generate sound to the mix buffer in mono */ +static void wiping_update_mono(void *param, stream_sample_t **inputs, stream_sample_t **outputs, int length) +{ + stream_sample_t *buffer = outputs[0]; + sound_channel *voice; + short *mix; + int i; + + /* if no sound, we're done */ + if (sound_enable == 0) + { + memset(buffer, 0, length * sizeof(*buffer)); + return; + } + + /* zap the contents of the mixer buffer */ + memset(mixer_buffer, 0, length * sizeof(short)); + + /* loop over each voice and add its contribution */ + for (voice = channel_list; voice < last_channel; voice++) + { + int f = 16*voice->frequency; + int v = voice->volume; + + /* only update if we have non-zero volume and frequency */ + if (v && f) + { + const UINT8 *w = voice->wave; + int c = voice->counter; + + mix = mixer_buffer; + + /* add our contribution */ + for (i = 0; i < length; i++) + { + int offs; + + c += f; + + if (voice->oneshot) + { + if (voice->oneshotplaying) + { + offs = (c >> 15); + if (w[offs>>1] == 0xff) + { + voice->oneshotplaying = 0; + } + + if (voice->oneshotplaying) + { + /* use full byte, first the high 4 bits, then the low 4 bits */ + if (offs & 1) + *mix++ += ((w[offs>>1] & 0x0f) - 8) * v; + else + *mix++ += (((w[offs>>1]>>4) & 0x0f) - 8) * v; + } + } + } + else + { + offs = (c >> 15) & 0x1f; + + /* use full byte, first the high 4 bits, then the low 4 bits */ + if (offs & 1) + *mix++ += ((w[offs>>1] & 0x0f) - 8) * v; + else + *mix++ += (((w[offs>>1]>>4) & 0x0f) - 8) * v; + } + } + + /* update the counter for this voice */ + voice->counter = c; + } + } + + /* mix it down */ + mix = mixer_buffer; + for (i = 0; i < length; i++) + *buffer++ = mixer_lookup[*mix++]; +} + + + +void *wiping_sh_start(int clock, const struct CustomSound_interface *config) +{ + sound_channel *voice; + + /* get stream channels */ + stream = stream_create(0, 1, samplerate, NULL, wiping_update_mono); + + /* allocate a pair of buffers to mix into - 1 second's worth should be more than enough */ + mixer_buffer = auto_malloc(2 * sizeof(short) * samplerate); + mixer_buffer_2 = mixer_buffer + samplerate; + + /* build the mixer table */ + if (make_mixer_table(8, defgain)) + return NULL; + + /* extract globals from the interface */ + num_voices = 8; + last_channel = channel_list + num_voices; + + sound_rom = memory_region(REGION_SOUND1); + sound_prom = memory_region(REGION_SOUND2); + + /* start with sound enabled, many games don't have a sound enable register */ + sound_enable = 1; + + /* reset all the voices */ + for (voice = channel_list; voice < last_channel; voice++) + { + voice->frequency = 0; + voice->volume = 0; + voice->wave = &sound_prom[0]; + voice->counter = 0; + } + + return auto_malloc(1); +} + + + +/********************************************************************************/ + +WRITE8_HANDLER( wiping_sound_w ) +{ + sound_channel *voice; + int base; + + /* update the streams */ + stream_update(stream); + + /* set the register */ + wiping_soundregs[offset] = data; + + /* recompute all the voice parameters */ + if (offset <= 0x3f) + { + for (base = 0, voice = channel_list; voice < last_channel; voice++, base += 8) + { + voice->frequency = wiping_soundregs[0x02 + base] & 0x0f; + voice->frequency = voice->frequency * 16 + ((wiping_soundregs[0x01 + base]) & 0x0f); + voice->frequency = voice->frequency * 16 + ((wiping_soundregs[0x00 + base]) & 0x0f); + + voice->volume = wiping_soundregs[0x07 + base] & 0x0f; + if (wiping_soundregs[0x5 + base] & 0x0f) + { + voice->wave = &sound_rom[128 * (16 * (wiping_soundregs[0x5 + base] & 0x0f) + + (wiping_soundregs[0x2005 + base] & 0x0f))]; + voice->oneshot = 1; + } + else + { + voice->wave = &sound_rom[16 * (wiping_soundregs[0x3 + base] & 0x0f)]; + voice->oneshot = 0; + voice->oneshotplaying = 0; + } + } + } + else if (offset >= 0x2000) + { + voice = &channel_list[(offset & 0x3f)/8]; + if (voice->oneshot) + { + voice->counter = 0; + voice->oneshotplaying = 1; + } + } +} |