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Diffstat (limited to 'src/mame/audio/tvc_snd.cpp')
-rw-r--r-- | src/mame/audio/tvc_snd.cpp | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/src/mame/audio/tvc_snd.cpp b/src/mame/audio/tvc_snd.cpp new file mode 100644 index 00000000000..29d61b5dc7c --- /dev/null +++ b/src/mame/audio/tvc_snd.cpp @@ -0,0 +1,142 @@ +// license:BSD-3-Clause +// copyright-holders:Sandro Ronco +/*************************************************************************** + + Videotone TVC 32/64 sound emulation + +***************************************************************************/ + +#include "emu.h" +#include "tvc_snd.h" + +// device type definition +const device_type TVC_SOUND = &device_creator<tvc_sound_device>; + +//------------------------------------------------- +// tvc_sound_device - constructor +//------------------------------------------------- + +tvc_sound_device::tvc_sound_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : + device_t(mconfig, TVC_SOUND, "TVC 64 Audio Custom", tag, owner, clock, "tvc_sound", __FILE__), + device_sound_interface(mconfig, *this), + m_write_sndint(*this) +{ +} + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- +void tvc_sound_device::device_start() +{ + // resolve callbacks + m_write_sndint.resolve_safe(); + + m_stream = machine().sound().stream_alloc(*this, 0, 1, machine().sample_rate()); + m_sndint_timer = timer_alloc(TIMER_SNDINT); +} + +//------------------------------------------------- +// device_reset - device-specific reset +//------------------------------------------------- +void tvc_sound_device::device_reset() +{ + m_enabled = 0; + m_freq = 0; + m_incr = 0; + m_signal = 1; + m_sndint_timer->reset(); +} + + +//------------------------------------------------- +// device_timer - handler timer events +//------------------------------------------------- + +void tvc_sound_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) +{ + m_write_sndint(1); +} + +//------------------------------------------------- +// sound_stream_update - handle update requests for +// our sound stream +//------------------------------------------------- + +void tvc_sound_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples) +{ + int rate = machine().sample_rate() / 2; + + if (m_enabled && m_freq) + { + while( samples-- > 0 ) + { + *outputs[0]++ = m_signal * (m_volume * 0x0800); + m_incr -= m_freq; + while(m_incr < 0) + { + m_incr += rate; + m_signal = -m_signal; + } + } + } + else + { + // fill output with 0 if the sound is disabled + memset(outputs[0], 0, samples * sizeof(stream_sample_t)); + } +} + + + +//------------------------------------------------- +// ports write +//------------------------------------------------- + +WRITE8_MEMBER(tvc_sound_device::write) +{ + m_stream->update(); + + m_ports[offset] = data; + + switch(offset) + { + case 1: + m_enabled = BIT(data, 4); + // fall through + + case 0: + { + UINT16 pitch = (m_ports[0] | (m_ports[1]<<8)) & 0x0fff; + m_freq = (pitch == 0x0fff) ? 0 : (int)(195312.5 / (4096 - pitch)); + + if ((m_ports[1] & 0x20) && m_freq != 0) + m_sndint_timer->adjust(attotime::from_hz(m_freq), 0, attotime::from_hz(m_freq)); + else + m_sndint_timer->reset(); + + break; + } + + case 2: + m_volume = (data>>2) & 0x0f; + break; + } +} + + +//------------------------------------------------- +// tvc_sound_device::reset_divider +//------------------------------------------------- + +void tvc_sound_device::reset_divider() +{ + m_stream->update(); + + m_incr = 0; + m_signal = 1; + + if (m_ports[1] & 0x20 && m_freq != 0) + m_sndint_timer->adjust(attotime::from_hz(m_freq), 0, attotime::from_hz(m_freq)); + else + m_sndint_timer->reset(); +} |