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off-by-one fixes, added notes, implemented panning

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This commit is contained in:
Michaël Banaan Ananas 2014-02-21 12:00:51 +00:00
parent b76a8dd22c
commit 88afb1b6af
1 changed files with 21 additions and 10 deletions
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31
src/emu/sound/zsg2.c
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@ -48,8 +48,7 @@ Emulation is still preliminary.
TODO: TODO:
- channel volume, 16bits?? need to make a lookup table? - channel volume, 16bits?? need to make a lookup table?
- how does panning work? it is not simply left/right volume - some samples are in stereo format?
- (some) samples are in stereo format?
- memory reads out of range sometimes - memory reads out of range sometimes
- a lot of unknowns - a lot of unknowns
@ -204,7 +203,7 @@ void zsg2_device::sound_stream_update(sound_stream &stream, stream_sample_t **in
if (m_chan[ch].step_ptr & 0x40000) if (m_chan[ch].step_ptr & 0x40000)
{ {
m_chan[ch].step_ptr &= 0xffff; m_chan[ch].step_ptr &= 0xffff;
if (++m_chan[ch].cur_pos > m_chan[ch].end_pos) if (++m_chan[ch].cur_pos >= m_chan[ch].end_pos)
{ {
// loop sample // loop sample
m_chan[ch].cur_pos = m_chan[ch].loop_pos; m_chan[ch].cur_pos = m_chan[ch].loop_pos;
@ -223,8 +222,8 @@ void zsg2_device::sound_stream_update(sound_stream &stream, stream_sample_t **in
//sample = (sample * (m_chan[ch].vol & 0xffff)) / 0x10000; //sample = (sample * (m_chan[ch].vol & 0xffff)) / 0x10000;
if (m_chan[ch].vol == 0) sample = 0; // temp hack to prevent stuck notes if (m_chan[ch].vol == 0) sample = 0; // temp hack to prevent stuck notes
mix_l += sample; mix_l += (sample * m_chan[ch].panl + sample * (0x1f - m_chan[ch].panr)) >> 5;
mix_r += sample; mix_r += (sample * m_chan[ch].panr + sample * (0x1f - m_chan[ch].panl)) >> 5;
} }
outputs[0][i] = mix_l / 48; outputs[0][i] = mix_l / 48;
@ -240,7 +239,7 @@ void zsg2_device::chan_w(int ch, int reg, UINT16 data)
switch (reg) switch (reg)
{ {
case 0x0: case 0x0:
// lo byte: always 0? // lo byte: unknown, 0 on most games
// hi byte: start address low // hi byte: start address low
m_chan[ch].start_pos = (m_chan[ch].start_pos & 0xff00) | (data >> 8 & 0xff); m_chan[ch].start_pos = (m_chan[ch].start_pos & 0xff00) | (data >> 8 & 0xff);
break; break;
@ -252,14 +251,22 @@ void zsg2_device::chan_w(int ch, int reg, UINT16 data)
m_chan[ch].page = data << 8 & 0xff0000; m_chan[ch].page = data << 8 & 0xff0000;
break; break;
case 0x2:
// no function? always 0
break;
case 0x3:
// unknown, always 0x0400
break;
case 0x4: case 0x4:
// frequency // frequency
m_chan[ch].step = data; m_chan[ch].step = data + 1;
break; break;
case 0x5: case 0x5:
// lo byte: loop address low // lo byte: loop address low
// hi byte: right(?) panning (high bits always 0) // hi byte: right panning (high bits always 0)
m_chan[ch].loop_pos = (m_chan[ch].loop_pos & 0xff00) | (data & 0xff); m_chan[ch].loop_pos = (m_chan[ch].loop_pos & 0xff00) | (data & 0xff);
m_chan[ch].panr = data >> 8 & 0x1f; m_chan[ch].panr = data >> 8 & 0x1f;
break; break;
@ -271,18 +278,22 @@ void zsg2_device::chan_w(int ch, int reg, UINT16 data)
case 0x7: case 0x7:
// lo byte: loop address high // lo byte: loop address high
// hi byte: left(?) panning (high bits always 0) // hi byte: left panning (high bits always 0)
m_chan[ch].loop_pos = (m_chan[ch].loop_pos & 0x00ff) | (data << 8 & 0xff00); m_chan[ch].loop_pos = (m_chan[ch].loop_pos & 0x00ff) | (data << 8 & 0xff00);
m_chan[ch].panl = data >> 8 & 0x1f; m_chan[ch].panl = data >> 8 & 0x1f;
break; break;
case 0x9:
// no function? always 0
break;
case 0xb: case 0xb:
// always writes 0 // always writes 0
// this register is read-only // this register is read-only
break; break;
case 0xe: case 0xe:
// channel volume, reg 0xc is also related? // channel volume, reg 0xa/0xc is also related?
m_chan[ch].vol = data; m_chan[ch].vol = data;
break; break;