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// license:BSD-3-Clause
// copyright-holders:Valley Bell
/* Sega 315-5641 / D77591 / 9442CA010 */
#include "emu.h"
#include "315-5641.h"
DEFINE_DEVICE_TYPE(SEGA_315_5641_PCM, sega_315_5641_pcm_device, "315_5641_pcm", "Sega 315-5641 PCM")
sega_315_5641_pcm_device::sega_315_5641_pcm_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: upd7759_device(mconfig, SEGA_315_5641_PCM, tag, owner, clock)
, m_fifocallback(*this)
, m_fifo_read(0)
, m_fifo_write(0)
{
m_md = 0; // enforce "slave" mode
}
void sega_315_5641_pcm_device::device_start()
{
upd7759_device::device_start();
save_item(NAME(m_fifo_data), 0x40);
save_item(NAME(m_fifo_read));
save_item(NAME(m_fifo_write));
}
void sega_315_5641_pcm_device::advance_state()
{
switch (m_state)
{
case STATE_DROP_DRQ:
if (!m_md)
{
// Slave Mode: get data from FIFO buffer
uint8_t fiforead = (m_fifo_read + 1) & 0x3F;
if (fiforead != m_fifo_write)
{
m_fifo_in = m_fifo_data[fiforead];
m_fifo_read = fiforead;
if (get_fifo_space() == 0x3F)
{
m_fifo_empty = true;
m_fifocallback(1);
}
}
}
break;
}
upd7759_device::advance_state();
}
void sega_315_5641_pcm_device::port_w(u8 data)
{
if (m_md)
{
// update the FIFO value
m_fifo_in = data;
}
else
{
m_fifo_data[m_fifo_write++] = data;
m_fifo_write &= 0x3F;
if (m_fifo_empty)
{
m_fifo_empty = false;
m_fifocallback(0);
}
}
}
void sega_315_5641_pcm_device::fifo_reset_w(u8 data)
{
bool reset = !!(data & 1);
if (!m_fifo_reset && reset)
{
m_fifo_read = 0x3F;
m_fifo_write = 0x00;
if (m_fifo_empty)
m_fifocallback(0);
m_fifo_empty = false;
}
m_fifo_reset = reset;
}
void sega_315_5641_pcm_device::internal_start_w(int state)
{
uint8_t oldstart = m_start;
uint8_t newstart = (state != 0);
if (!m_md && m_reset && !oldstart && newstart)
{
// Somewhere between "Reset Off" and the first sample data,
// we need to send a few commands to make the sample stream work.
// Doing that when rising the "start" line seems to work fine.
port_w(0xFF); // "Last Sample" value (must be >= 0x10)
port_w(0x00); // Dummy 1
port_w(0x00); // Addr MSB
port_w(0x00); // Addr LSB
}
upd7759_device::internal_start_w(state);
}
uint8_t sega_315_5641_pcm_device::get_fifo_space()
{
return (m_fifo_read - m_fifo_write) & 0x3F;
}
void sega_315_5641_pcm_device::device_reset()
{
upd7759_device::device_reset();
m_fifo_read = 0x3F;
m_fifo_write = 0x00;
m_fifo_reset = false;
if (m_fifo_empty)
m_fifocallback(0);
m_fifo_empty = false;
}
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