com.github.anilople.javajvm.instructions.comparisons.DCMPG Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of javajvm Show documentation

Use Java to Implement JVM

The newest version!

package com.github.anilople.javajvm.instructions.comparisons;

import com.github.anilople.javajvm.instructions.BytecodeReader;
import com.github.anilople.javajvm.instructions.Instruction;
import com.github.anilople.javajvm.runtimedataarea.Frame;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Operation
 * Compare double
 *
 * Operand ..., value1, value2 →
 * Stack ..., result
 *
 *
 */
public class DCMPG implements Instruction {

    private static final Logger logger = LoggerFactory.getLogger(DCMPG.class);

    @Override
    public void fetchOperands(BytecodeReader bytecodeReader) {

    }

    @Override
    public void execute(Frame frame) {
        double value2 = frame.getOperandStacks().popDoubleValue();
        double value1 = frame.getOperandStacks().popDoubleValue();
        logger.trace("double compare: [{}] [{}]", value1, value2);
        if(value1 > value2) {
            frame.getOperandStacks().pushIntValue(1);
        } else if(value1 == value2) {
            frame.getOperandStacks().pushIntValue(0);
        } else if(value1 < value2) {
            frame.getOperandStacks().pushIntValue(-1);
        } else {
            logger.debug("at least one is NaN. [{}] [{}]", value1, value2);
            //  at least one of value1' or value2' is NaN
            // The dcmpg instruction pushes the int value 1 onto the operand stack
            frame.getOperandStacks().pushIntValue(1);
        }
        int nextPc = frame.getNextPc() + this.size();
        frame.setNextPc(nextPc);
    }

    @Override
    public int size() {
        return 1;
    }

}