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// license:BSD-3-Clause
// copyright-holders:Juergen Buchmueller
/*****************************************************************************
*
* Xerox AltoII display horizontal task
*
*****************************************************************************/
#include "alto2cpu.h"
/**
* @brief f1_dht_block early: disable the display word task
*/
void alto2_cpu_device::f1_early_dht_block()
{
m_dsp.dht_blocks = true;
// clear the wakeup for the display horizontal task
m_task_wakeup &= ~(1 << m_task);
LOG((this,LOG_DHT,2," BLOCK %s\n", task_name(m_task)));
}
/**
* @brief f2_dht_setmode late: set the next scanline's mode inverse and half clock and branch
*
* BUS[0] selects the pixel clock (0), or half pixel clock (1)
* BUS[1] selects normal mode (0), or inverse mode (1)
*
* The current BUS[0] drives the NEXT[09] line, i.e. branches to 0 or 1
*/
void alto2_cpu_device::f2_late_dht_setmode()
{
UINT16 r = X_RDBITS(m_bus,16,0,0);
m_dsp.setmode = m_bus;
LOG((this,LOG_DHT,2," SETMODE<- BUS (%#o), branch on BUS[0] (%#o | %#o)\n", m_bus, m_next2, r));
m_next2 |= r;
}
/**
* @brief called by the CPU when the display horizontal task becomes active
*/
void alto2_cpu_device::activate_dht()
{
m_task_wakeup &= ~(1 << m_task);
}
/**
* @brief initialize the display horizontal task
*
* @param task task number
*/
void alto2_cpu_device::init_dht(int task)
{
set_f1(task, f1_block, &alto2_cpu_device::f1_early_dht_block, nullptr);
set_f2(task, f2_dht_evenfield, nullptr, &alto2_cpu_device::f2_late_evenfield);
set_f2(task, f2_dht_setmode, nullptr, &alto2_cpu_device::f2_late_dht_setmode);
m_active_callback[task] = &alto2_cpu_device::activate_dht;
}
void alto2_cpu_device::exit_dht()
{
// nothing to do yet
}
void alto2_cpu_device::reset_dht()
{
m_dsp.dht_blocks = true;
m_dsp.setmode = 0;
}
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