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// license:BSD-3-Clause
// copyright-holders:Juergen Buchmueller
/*****************************************************************************
 *
 *   Xerox AltoII display vertical task
 *
 *****************************************************************************/
#include "alto2cpu.h"

/*
 * Copied from ALTOCODE24.MU
 *
 *  ;Display Vertical Task
 *
 *  DVT:    MAR← L← DASTART+1;
 *      CBA← L, L← 0;
 *      CURDATA← L;
 *      SLC← L;
 *      T← MD;          CAUSE A VERTICAL FIELD INTERRUPT
 *      L← NWW OR T;
 *      MAR← CURLOC;        SET UP THE CURSOR
 *      NWW← L, T← 0-1;
 *      L← MD XOR T;        HARDWARE EXPECTS X COMPLEMENTED
 *      T← MD, EVENFIELD;
 *      CURX← L, :DVT1;
 *
 *  DVT1:   L← BIAS-T-1, TASK, :DVT2;   BIAS THE Y COORDINATE
 *  DVT11:  L← BIAS-T, TASK;
 *
 *  DVT2:   YPOS← L, :DVT;
 */

/**
 * @brief f1_dvt_block early: disable the display word task
 */
void alto2_cpu_device::f1_early_dvt_block()
{
//  m_task_wakeup &= ~(1 << m_task);
	LOG((this,LOG_DVT,2,"    BLOCK %s\n", task_name(m_task)));
}


/**
 * @brief called by the CPU when the display vertical task becomes active
 */
void alto2_cpu_device::activate_dvt()
{
	m_task_wakeup &= ~(1 << m_task);
}

/**
 * @brief initialize display vertical task
 */
void alto2_cpu_device::init_dvt(int task)
{
}

void alto2_cpu_device::exit_dvt()
{
	// nothing to do yet
}

void alto2_cpu_device::reset_dvt()
{
	// nothing to do yet
}