DLatch.cpp

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// Copyright 2015 - 2026, GIBIS-UNIFESP and the wiRedPanda contributors
// SPDX-License-Identifier: GPL-3.0-or-later
 
#include "App/Element/GraphicElements/DLatch.h"
 
#include "App/Element/ElementFactory.h"
#include "App/Element/ElementInfo.h"
#include "App/Wiring/Port.h"
 
template<>
struct ElementInfo<DLatch> {
    static constexpr ElementConstraints constraints{
        .type = ElementType::DLatch,
        .group = ElementGroup::Memory,
        .minInputSize = 2,
        .maxInputSize = 2,
        .minOutputSize = 2,
        .maxOutputSize = 2,
        .canChangeAppearance = true,
    };
    static_assert(validate(constraints));
 
    static ElementMetadata metadata()
    {
        auto meta = metadataFromConstraints(constraints);
        meta.pixmapPath = []{ return DLatch::pixmapPath(); };
        meta.titleText = QT_TRANSLATE_NOOP("DLatch", "D-LATCH");
        meta.translatedName = QT_TRANSLATE_NOOP("DLatch", "D-Latch");
        meta.trContext = "DLatch";
        return meta;
    }
 
    static inline const bool registered = []() {
        ElementMetadataRegistry::registerMetadata(metadata());
        ElementFactory::registerCreator(constraints.type, [] { return new DLatch(); });
        return true;
    }();
};
 
DLatch::DLatch(QGraphicsItem *parent)
    : GraphicElement(ElementType::DLatch, parent)
{
    // Call the most-derived override explicitly (see SRFlipFlop.cpp for rationale).
    DLatch::updatePortsProperties();
}
 
void DLatch::updatePortsProperties()
{
    // D latch has no clock — it is level-sensitive: Q tracks D while Enable is HIGH.
    // No asynchronous preset/clear inputs, so only 2 inputs total.
    inputPort(0)->setPos(0, 16);      inputPort(0)->setName("Data");
    inputPort(1)->setPos(0, 48);      inputPort(1)->setName("Enable");
 
    outputPort(0)->setPos(64, 16);    outputPort(0)->setName("Q");
    outputPort(1)->setPos(64, 48);    outputPort(1)->setName("~Q");
 
    // Initial state: Q=0, ~Q=1
    outputPort(0)->setDefaultStatus(Status::Inactive);
    outputPort(1)->setDefaultStatus(Status::Active);
}
 
void DLatch::updateTheme()
{
    // Reload the pixmap before delegating to the base class (see SRFlipFlop.cpp).
    setPixmap(pixmapPath());
    GraphicElement::updateTheme();
}
 
void DLatch::updateLogic()
{
    if (!simUpdateInputs()) {
        return;
    }
    Status q0 = simOutputs().at(0);
    Status q1 = simOutputs().at(1);
    const Status D = simInputs().at(0);
    const Status enable = simInputs().at(1);
 
    if (enable == Status::Active) {
        q0 = D;
        q1 = (D == Status::Active) ? Status::Inactive : Status::Active;
    }
 
    setOutputValue(0, q0);
    setOutputValue(1, q1);
}