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ymz770.cpp: add pan, main volume level and clip limit control

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This commit is contained in:
MetalliC 2017-10-26 22:23:17 +03:00
parent 30a55d8974
commit 95ad1a3d81
1 changed files with 35 additions and 5 deletions
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40
src/devices/sound/ymz770.cpp
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@ -11,8 +11,8 @@
TODO:
- A lot of unimplemented features, even simple ones like panning,
these should be added once we find out any software that uses it.
- Is channel volume linear(current implementation) or logarithmic?
- Sequencer is very preliminary
- verify if pan 100% correct
- What does channel ATBL mean?
- Is YMZ774(and other variants) the same family as this chip?
What are the differences?
@ -167,14 +167,17 @@ void ymz770_device::sound_stream_update(sound_stream &stream, stream_sample_t **
}
// process channels
int32_t mix = 0;
int32_t mixl = 0;
int32_t mixr = 0;
for (auto & elem : m_channels)
{
if (elem.output_remaining > 0)
{
// force finish current block
mix += (elem.output_data[elem.output_ptr++]*elem.volume);
int32_t smpl = elem.output_data[elem.output_ptr++] * elem.volume; // volume is linear, 0 - 128 (100%)
mixr += (smpl * elem.pan) >> 11; // pan seems linear, 0 - 16, where 0 = 100% left, 16 = 100% right, 8 = 50% left 50% right
mixl += (smpl * (16 - elem.pan)) >> 11;
elem.output_remaining--;
if (elem.output_remaining == 0 && !elem.is_playing)
@ -217,12 +220,39 @@ retry:
elem.output_remaining--;
elem.output_ptr = 1;
mix += (elem.output_data[0]*elem.volume);
int32_t smpl = elem.output_data[0] * elem.volume;
mixr += (smpl * elem.pan) >> 11;
mixl += (smpl * (16 - elem.pan)) >> 11;
}
}
}
outL[i] = outR[i] = mix>>8;
mixr *= m_vlma; // main volume is linear, 0 - 255, where 128 = 100%
mixl *= m_vlma;
mixr >>= 7 - m_bsl;
mixl >>= 7 - m_bsl;
// Clip limiter: 0 - off, 1 - 6.02 dB (100%), 2 - 4.86 dB (87.5%), 3 - 3.52 dB (75%). values taken from YMZ773 docs, might be incorrect for YMZ770.
constexpr int32_t ClipMax3 = 32768 * 75 / 100;
constexpr int32_t ClipMax2 = 32768 * 875 / 1000;
switch (m_cpl)
{
case 3:
mixl = (mixl > ClipMax3) ? ClipMax3 : (mixl < -ClipMax3) ? -ClipMax3 : mixl;
mixr = (mixr > ClipMax3) ? ClipMax3 : (mixr < -ClipMax3) ? -ClipMax3 : mixr;
break;
case 2:
mixl = (mixl > ClipMax2) ? ClipMax2 : (mixl < -ClipMax2) ? -ClipMax2 : mixl;
mixr = (mixr > ClipMax2) ? ClipMax2 : (mixr < -ClipMax2) ? -ClipMax2 : mixr;
break;
case 1:
mixl = (mixl > 32767) ? 32767 : (mixl < -32768) ? -32768 : mixl;
mixr = (mixr > 32767) ? 32767 : (mixr < -32768) ? -32768 : mixr;
break;
}
if (m_mute)
mixr = mixl = 0;
outL[i] = mixl;
outR[i] = mixr;
}
}