// license:BSD-3-Clause
// copyright-holders:Hiromitsu Shioya, Olivier Galibert
/*********************************************************/
/* SEGA 16ch 8bit PCM */
/*********************************************************/
#include "emu.h"
#include "segapcm.h"
#include <algorithm>
// device type definition
DEFINE_DEVICE_TYPE(SEGAPCM, segapcm_device, "segapcm", "Sega PCM")
//-------------------------------------------------
// segapcm_device - constructor
//-------------------------------------------------
segapcm_device::segapcm_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, SEGAPCM, tag, owner, clock)
, device_sound_interface(mconfig, *this)
, device_rom_interface(mconfig, *this, 21)
, m_ram(nullptr)
, m_bankshift(12)
, m_bankmask(0x70)
, m_stream(nullptr)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void segapcm_device::device_start()
{
m_ram = std::make_unique<uint8_t[]>(0x800);
std::fill(&m_ram[0], &m_ram[0x800], 0xff);
m_stream = stream_alloc(0, 2, clock() / 128);
save_item(NAME(m_low));
save_pointer(NAME(m_ram), 0x800);
}
//-------------------------------------------------
// device_clock_changed - called if the clock
// changes
//-------------------------------------------------
void segapcm_device::device_clock_changed()
{
m_stream->set_sample_rate(clock() / 128);
}
//-------------------------------------------------
// rom_bank_updated - the rom bank has changed
//-------------------------------------------------
void segapcm_device::rom_bank_updated()
{
m_stream->update();
}
//-------------------------------------------------
// sound_stream_update - handle a stream update
//-------------------------------------------------
void segapcm_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
{
/* clear the buffers */
memset(outputs[0], 0, samples*sizeof(*outputs[0]));
memset(outputs[1], 0, samples*sizeof(*outputs[1]));
// reg function
// ------------------------------------------------
// 0x00 ?
// 0x01 ?
// 0x02 volume left
// 0x03 volume right
// 0x04 loop address (08-15)
// 0x05 loop address (16-23)
// 0x06 end address
// 0x07 address delta
// 0x80 ?
// 0x81 ?
// 0x82 ?
// 0x83 ?
// 0x84 current address (08-15), 00-07 is internal?
// 0x85 current address (16-23)
// 0x86 bit 0: channel disable?
// bit 1: loop disable
// other bits: bank
// 0x87 ?
/* loop over channels */
for (int ch = 0; ch < 16; ch++)
{
uint8_t *regs = m_ram.get()+8*ch;
/* only process active channels */
if (!(regs[0x86]&1))
{
int offset = (regs[0x86] & m_bankmask) << m_bankshift;
uint32_t addr = (regs[0x85] << 16) | (regs[0x84] << 8) | m_low[ch];
uint32_t loop = (regs[0x05] << 16) | (regs[0x04] << 8);
uint8_t end = regs[6] + 1;
int i;
/* loop over samples on this channel */
for (i = 0; i < samples; i++)
{
int8_t v;
/* handle looping if we've hit the end */
if ((addr >> 16) == end)
{
if (regs[0x86] & 2)
{
regs[0x86] |= 1;
break;
}
else addr = loop;
}
/* fetch the sample */
v = read_byte(offset + (addr >> 8)) - 0x80;
/* apply panning and advance */
outputs[0][i] += v * (regs[2] & 0x7f);
outputs[1][i] += v * (regs[3] & 0x7f);
addr = (addr + regs[7]) & 0xffffff;
}
/* store back the updated address */
regs[0x84] = addr >> 8;
regs[0x85] = addr >> 16;
m_low[ch] = regs[0x86] & 1 ? 0 : addr;
}
}
}
WRITE8_MEMBER( segapcm_device::sega_pcm_w )
{
m_stream->update();
m_ram[offset & 0x07ff] = data;
}
READ8_MEMBER( segapcm_device::sega_pcm_r )
{
m_stream->update();
return m_ram[offset & 0x07ff];
}