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// license:BSD-3-Clause
// copyright-holders:Juergen Buchmueller
/*****************************************************************************
*
* Xerox AltoII display word task
*
*****************************************************************************/
#include "alto2cpu.h"
//! PROM a38 bit O1 is STOPWAKE' (stop DWT if bit is zero)
#define FIFO_STOPWAKE(a38) (0 == (a38 & disp_a38_STOPWAKE) ? true : false)
/**
* @brief block the display word task
*/
void alto2_cpu_device::f1_early_dwt_block()
{
m_dsp.dwt_blocks = true;
/* clear the wakeup for the display word task */
m_task_wakeup &= ~(1 << m_task);
LOG((this,LOG_DWT,2," BLOCK %s\n", task_name(m_task)));
/* wakeup the display horizontal task, if it didn't block itself */
if (!m_dsp.dht_blocks)
m_task_wakeup |= 1 << task_dht;
}
/**
* @brief load the display data register
*/
void alto2_cpu_device::f2_late_dwt_load_ddr()
{
LOG((this,LOG_DWT,2," DDR<- BUS (%#o)\n", m_bus));
m_dsp.fifo[m_dsp.wa] = m_bus;
m_dsp.wa = (m_dsp.wa + 1) % ALTO2_DISPLAY_FIFO;
UINT8 a38 = m_disp_a38[m_dsp.ra * 16 + m_dsp.wa];
if (FIFO_STOPWAKE(a38))
m_task_wakeup &= ~(1 << task_dwt);
LOG((this,LOG_DWT,2, " DWT push %04x into FIFO[%02o]%s\n",
m_bus, (m_dsp.wa - 1) & (ALTO2_DISPLAY_FIFO - 1),
FIFO_STOPWAKE(a38) ? " STOPWAKE" : ""));
}
void alto2_cpu_device::init_dwt(int task)
{
set_f1(task, f1_block, &alto2_cpu_device::f1_early_dwt_block, nullptr);
set_f2(task, f2_dwt_load_ddr, nullptr, &alto2_cpu_device::f2_late_dwt_load_ddr);
}
void alto2_cpu_device::exit_dwt()
{
// nothing to do yet
}
void alto2_cpu_device::reset_dwt()
{
m_dsp.dwt_blocks = false;
memset(m_dsp.fifo, 0, sizeof(m_dsp.fifo));
m_dsp.wa = 0;
m_dsp.ra = 0;
}
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