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Implemented pan for stereo support for ics2115 (#8489)

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nabetse 2021-08-27 13:32:29 +02:00 committed by GitHub
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2 changed files with 35 additions and 28 deletions
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62
src/devices/sound/ics2115.cpp
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@ -1,5 +1,5 @@
// license:BSD-3-Clause
// copyright-holders:Alex Marshall,nimitz,austere
// copyright-holders:Alex Marshall, nimitz, austere
/*
ICS2115 by Raiden II team (c) 2010
members: austere, nimitz, Alex Marshal
@ -9,16 +9,11 @@
Use tab size = 4 for your viewing pleasure.
TODO:
- Implement Panning, Chip has support stereo
- Verify BYTE/ROMEN pin behaviors
- Verify BYTE/ROMEN pin behavior
- DRAM, DMA, MIDI interface is unimplemented
- Verify interrupt, envelope, timer period
- Verify unemulated registers
Changelog:
25th july 2020 [cam900]:
- Improve envelope behavior, Improve debugging registers, Fix ramping
*/
#include "emu.h"
@ -31,6 +26,7 @@
//#define ICS2115_DEBUG
//#define ICS2115_ISOLATE 6
// device type definition
DEFINE_DEVICE_TYPE(ICS2115, ics2115_device, "ics2115", "ICS2115 WaveFront Synthesizer")
@ -87,13 +83,20 @@ void ics2115_device::device_start()
const u16 lut_initial = 33 << 2; //shift up 2-bits for 16-bit range.
for (int i = 0; i < 8; i++)
lut[i] = (lut_initial << i) - lut_initial;
//pan law level
//log2(256*128) = 15 for -3db + 1 must be confirmed by real hardware owners
constexpr int PAN_LEVEL = 16;
for (int i = 0; i < 256; i++)
{
u8 exponent = (~i >> 4) & 0x07;
u8 mantissa = ~i & 0x0f;
s16 value = lut[exponent] + (mantissa << (exponent + 3));
m_ulaw[i] = (i & 0x80) ? -value : value;
m_panlaw[i] = PAN_LEVEL - (31 - count_leading_zeros_32(i)); //m_panlaw[i] = PAN_LEVEL - log2(i)
}
m_panlaw[0] = 0xfff; //all bits to one when no pan
save_item(NAME(m_timer[0].period));
save_item(NAME(m_timer[0].scale));
@ -204,23 +207,23 @@ device_memory_interface::space_config_vector ics2115_device::memory_space_config
/*
Using next-state logic from column 126 of patent 5809466.
VOL(L) = vol.acc
VINC = vol.inc
DIR = invert
BC = boundary cross (start or end )
BLEN = bi directional loop enable
LEN loop enable
UVOL LEN BLEN DIR BC Next VOL(L)
0 x x x x VOL(L) // no change no vol envelope
1 x x 0 0 VOL(L) + VINC // foward dir no bc
1 x x 1 0 VOL(L) - VINC // invert no bc
1 0 x x 1 VOL(L) // no env len no vel envelope
----------------------------------------------------------------------------
1 1 0 0 1 start - ( end - (VOL(L) + VINC) )
1 1 0 1 1 end + ( (VOL(L) - VINC) - start)
1 1 1 0 1 end + (end - (VOL(L) + VINC) ) // here
1 1 1 1 1 start - ( (VOL(L) - VINC)- start)
Using next-state logic from column 126 of patent 5809466.
VOL(L) = vol.acc
VINC = vol.inc
DIR = invert
BC = boundary cross (start or end )
BLEN = bi directional loop enable
LEN loop enable
UVOL LEN BLEN DIR BC Next VOL(L)
0 x x x x VOL(L) // no change no vol envelope
1 x x 0 0 VOL(L) + VINC // forward dir no bc
1 x x 1 0 VOL(L) - VINC // invert no bc
1 0 x x 1 VOL(L) // no env len no vol envelope
----------------------------------------------------------------------------
1 1 0 0 1 start - ( end - (VOL(L) + VINC) )
1 1 0 1 1 end + ( (VOL(L) - VINC) - start)
1 1 1 0 1 end + (end - (VOL(L) + VINC) ) // here
1 1 1 1 1 start - ( (VOL(L) - VINC)- start)
*/
int ics2115_device::ics2115_voice::update_volume_envelope()
{
@ -429,10 +432,13 @@ int ics2115_device::fill_output(ics2115_voice& voice, std::vector<write_stream_v
for (int i = 0; i < outputs[0].samples(); i++)
{
const u32 volacc = (voice.vol.acc >> 10) & 0xffff;
const u32 volume = (m_volume[volacc >> 4] * voice.state.ramp) >> 6;
const u16 vleft = volume; //* (255 - voice.vol.pan) / 0x80];
const u16 vright = volume; //* (voice.vol.pan + 1) / 0x80];
constexpr int RAMP_SHIFT = 6;
const u32 volacc = (voice.vol.acc >> 14) & 0xfff;
const u16 vlefti = volacc - m_panlaw[255 - voice.vol.pan]; // left index from acc - pan law
const u16 vrighti = volacc - m_panlaw[voice.vol.pan]; // right index from acc - pan law
//check negative values so no cracks, is it a hardware feature ?
const u16 vleft = vlefti > 0 ? (m_volume[vlefti] * voice.state.ramp >> RAMP_SHIFT) : 0;
const u16 vright = vrighti > 0 ? (m_volume[vrighti] * voice.state.ramp >> RAMP_SHIFT) : 0;
//From GUS doc:
//In general, it is necessary to remember that all voices are being summed in to the

1
src/devices/sound/ics2115.h
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@ -132,6 +132,7 @@ private:
s16 m_ulaw[256];
u16 m_volume[4096];
u16 m_panlaw[256];
static const int volume_bits = 15;
ics2115_voice m_voice[32];