Low-Level Memory Access

/**
 * Base interface for all word-sized value types
 */
public interface WordBase {
    /** Convert word to raw long value */
    long rawValue();
}

/**
 * Word values that support comparison operations
 */
public interface ComparableWord extends WordBase {
    /** Test equality with another word */
    boolean equal(ComparableWord val);
    
    /** Test inequality with another word */
    boolean notEqual(ComparableWord val);
    
    /** Test if this word is less than another */
    boolean lessThan(ComparableWord val);
    
    /** Test if this word is less than or equal to another */
    boolean lessOrEqual(ComparableWord val);
    
    /** Test if this word is greater than another */
    boolean greaterThan(ComparableWord val);
    
    /** Test if this word is greater than or equal to another */
    boolean greaterOrEqual(ComparableWord val);
    
    /** Get word representing value above this word */
    ComparableWord aboveThan(ComparableWord val);
    
    /** Get word representing value below this word */
    ComparableWord belowThan(ComparableWord val);
    
    /** Get word representing value above or equal to this word */
    ComparableWord aboveOrEqual(ComparableWord val);
    
    /** Get word representing value below or equal to this word */
    ComparableWord belowOrEqual(ComparableWord val);
}

import org.graalvm.word.*;

public class WordComparison {
    public void compareWords() {
        UnsignedWord a = WordFactory.unsigned(100);
        UnsignedWord b = WordFactory.unsigned(200);
        
        if (a.lessThan(b)) {
            System.out.println("a is less than b");
        }
        
        if (a.notEqual(b)) {
            System.out.println("a and b are different");
        }
        
        // Raw value access
        long rawA = a.rawValue(); // 100
    }
}

/**
 * Unsigned word with arithmetic operations
 */
public interface UnsignedWord extends ComparableWord {
    /** Add unsigned value */
    UnsignedWord add(UnsignedWord val);
    
    /** Add signed integer value */
    UnsignedWord add(int val);
    
    /** Subtract unsigned value */
    UnsignedWord subtract(UnsignedWord val);
    
    /** Subtract signed integer value */
    UnsignedWord subtract(int val);
    
    /** Multiply by unsigned value */
    UnsignedWord multiply(UnsignedWord val);
    
    /** Multiply by signed integer value */
    UnsignedWord multiply(int val);
    
    /** Unsigned division */
    UnsignedWord unsignedDivide(UnsignedWord val);
    
    /** Unsigned remainder */
    UnsignedWord unsignedRemainder(UnsignedWord val);
    
    /** Shift left by number of bits */
    UnsignedWord shiftLeft(UnsignedWord n);
    
    /** Unsigned shift right by number of bits */
    UnsignedWord unsignedShiftRight(UnsignedWord n);
    
    /** Bitwise AND operation */
    UnsignedWord and(UnsignedWord val);
    
    /** Bitwise OR operation */
    UnsignedWord or(UnsignedWord val);
    
    /** Bitwise XOR operation */
    UnsignedWord xor(UnsignedWord val);
    
    /** Bitwise NOT operation */
    UnsignedWord not();
}

public class UnsignedArithmetic {
    public void performCalculations() {
        UnsignedWord size = WordFactory.unsigned(1024);
        UnsignedWord blockSize = WordFactory.unsigned(64);
        
        // Calculate number of blocks
        UnsignedWord numBlocks = size.unsignedDivide(blockSize);
        System.out.println("Number of blocks: " + numBlocks.rawValue()); // 16
        
        // Align size to block boundary
        UnsignedWord mask = blockSize.subtract(1);
        UnsignedWord aligned = size.add(mask).and(mask.not());
        
        // Safe overflow handling
        UnsignedWord maxValue = WordFactory.unsigned(Long.MAX_VALUE);
        UnsignedWord result = maxValue.add(1); // Wraps around safely
        
        // Bit manipulation
        UnsignedWord flags = WordFactory.unsigned(0);
        flags = flags.or(WordFactory.unsigned(0x01)); // Set bit 0
        flags = flags.and(WordFactory.unsigned(0xFE).not()); // Clear bit 0
    }
}

/**
 * Signed word with arithmetic operations
 */
public interface SignedWord extends ComparableWord {
    /** Add signed value */
    SignedWord add(SignedWord val);
    
    /** Add integer value */
    SignedWord add(int val);
    
    /** Subtract signed value */
    SignedWord subtract(SignedWord val);
    
    /** Subtract integer value */
    SignedWord subtract(int val);
    
    /** Multiply by signed value */
    SignedWord multiply(SignedWord val);
    
    /** Multiply by integer value */
    SignedWord multiply(int val);
    
    /** Signed division */
    SignedWord signedDivide(SignedWord val);
    
    /** Signed remainder */
    SignedWord signedRemainder(SignedWord val);
    
    /** Shift left by number of bits */
    SignedWord shiftLeft(UnsignedWord n);
    
    /** Signed shift right by number of bits */
    SignedWord signedShiftRight(UnsignedWord n);
    
    /** Bitwise AND operation */
    SignedWord and(SignedWord val);
    
    /** Bitwise OR operation */
    SignedWord or(SignedWord val);
    
    /** Bitwise XOR operation */
    SignedWord xor(SignedWord val);
    
    /** Bitwise NOT operation */
    SignedWord not();
}

/**
 * Base interface for pointer types
 */
public interface PointerBase extends ComparableWord {
    /** Check if pointer is null */
    boolean isNull();
    
    /** Check if pointer is not null */
    boolean isNonNull();
}

/**
 * Pointer with arithmetic and memory access operations
 */
public interface Pointer extends UnsignedWord, PointerBase {
    /** Read byte at offset */
    byte readByte(UnsignedWord offset);
    
    /** Read byte at word-sized offset */
    byte readByte(int wordOffset);
    
    /** Write byte at offset */
    void writeByte(UnsignedWord offset, byte val);
    
    /** Write byte at word-sized offset */
    void writeByte(int wordOffset, byte val);
    
    /** Read char at offset */
    char readChar(UnsignedWord offset);
    
    /** Write char at offset */
    void writeChar(UnsignedWord offset, char val);
    
    /** Read short at offset */
    short readShort(UnsignedWord offset);
    
    /** Write short at offset */
    void writeShort(UnsignedWord offset, short val);
    
    /** Read int at offset */
    int readInt(UnsignedWord offset);
    
    /** Write int at offset */
    void writeInt(UnsignedWord offset, int val);
    
    /** Read long at offset */
    long readLong(UnsignedWord offset);
    
    /** Write long at offset */
    void writeLong(UnsignedWord offset, long val);
    
    /** Read float at offset */
    float readFloat(UnsignedWord offset);
    
    /** Write float at offset */
    void writeFloat(UnsignedWord offset, float val);
    
    /** Read double at offset */
    double readDouble(UnsignedWord offset);
    
    /** Write double at offset */
    void writeDouble(UnsignedWord offset, double val);
    
    /** Read word at offset */
    <T extends WordBase> T readWord(UnsignedWord offset);
    
    /** Write word at offset */
    void writeWord(UnsignedWord offset, WordBase val);
    
    /** Read object reference at offset */
    Object readObject(UnsignedWord offset);
    
    /** Write object reference at offset */
    void writeObject(UnsignedWord offset, Object val);
    
    /** Compare memory regions */
    int compareAndSwapInt(UnsignedWord offset, int expectedValue, int newValue);
    
    /** Compare memory regions for long values */
    long compareAndSwapLong(UnsignedWord offset, long expectedValue, long newValue);
    
    /** Compare memory regions for word values */
    <T extends WordBase> T compareAndSwapWord(UnsignedWord offset, T expectedValue, T newValue);
    
    /** Compare memory regions for object references */
    Object compareAndSwapObject(UnsignedWord offset, Object expectedValue, Object newValue);
}

public class PointerOperations {
    public void accessMemory() {
        // Allocate native memory (conceptual - actual allocation varies)
        Pointer memory = allocateMemory(1024);
        
        if (memory.isNonNull()) {
            // Write data to memory
            memory.writeInt(WordFactory.unsigned(0), 42);
            memory.writeInt(WordFactory.unsigned(4), 100);
            
            // Read data back
            int first = memory.readInt(WordFactory.unsigned(0));
            int second = memory.readInt(WordFactory.unsigned(4));
            
            System.out.println("First: " + first + ", Second: " + second);
            
            // Pointer arithmetic
            Pointer secondInt = memory.add(4);
            int value = secondInt.readInt(WordFactory.unsigned(0));
            
            // Atomic operations
            int oldValue = memory.compareAndSwapInt(
                WordFactory.unsigned(0), 42, 84);
            if (oldValue == 42) {
                System.out.println("Successfully updated value");
            }
        }
    }
    
    // Placeholder for memory allocation
    private native Pointer allocateMemory(int size);
}

/**
 * Factory for creating word values from primitives
 */
public final class WordFactory {
    /** Create zero-valued unsigned word */
    public static UnsignedWord zero();
    
    /** Create null pointer */
    public static <T extends PointerBase> T nullPointer();
    
    /** Create unsigned word from long value */
    public static UnsignedWord unsigned(long val);
    
    /** Create unsigned word from int value */
    public static UnsignedWord unsigned(int val);
    
    /** Create signed word from long value */
    public static SignedWord signed(long val);
    
    /** Create signed word from int value */
    public static SignedWord signed(int val);
    
    /** Create pointer from long address */
    public static <T extends PointerBase> T pointer(long val);
    
    /** Create word from raw value */
    public static <T extends WordBase> T fromRawValue(Class<T> type, long rawValue);
}

public class WordFactoryUsage {
    public void createWords() {
        // Create various word types
        UnsignedWord pageSize = WordFactory.unsigned(4096);
        SignedWord offset = WordFactory.signed(-100);
        Pointer nullPtr = WordFactory.nullPointer();
        
        // Zero and max values
        UnsignedWord zero = WordFactory.zero();
        UnsignedWord maxUnsigned = WordFactory.unsigned(-1L); // All bits set
        
        // Convert between types
        long rawValue = pageSize.rawValue();
        UnsignedWord restored = WordFactory.unsigned(rawValue);
        
        // Null checks
        if (nullPtr.isNull()) {
            System.out.println("Pointer is null");
        }
        
        // Create typed pointers
        Pointer buffer = WordFactory.pointer(0x1000L);
        if (buffer.isNonNull()) {
            // Use buffer...
        }
    }
}

/**
 * Memory synchronization and barriers
 */
public final class MemoryBarriers {
    /** Full memory barrier */
    public static void fullBarrier();
    
    /** Load memory barrier */
    public static void loadBarrier();
    
    /** Store memory barrier */
    public static void storeBarrier();
    
    /** Load-store memory barrier */
    public static void loadStoreBarrier();
    
    /** Store-load memory barrier */
    public static void storeLoadBarrier();
}

/**
 * Atomic operations on word values
 */
public final class AtomicOperations {
    /** Atomic load with acquire semantics */
    public static <T extends WordBase> T loadAcquire(Pointer address);
    
    /** Atomic store with release semantics */
    public static void storeRelease(Pointer address, WordBase value);
    
    /** Atomic compare-and-swap */
    public static <T extends WordBase> T compareAndSwap(
        Pointer address, T expectedValue, T newValue);
    
    /** Atomic fetch-and-add */
    public static UnsignedWord fetchAndAdd(Pointer address, UnsignedWord delta);
    
    /** Atomic fetch-and-subtract */
    public static UnsignedWord fetchAndSubtract(Pointer address, UnsignedWord delta);
}

// Platform-specific word sizes
public interface WordSize {
    /** Get size of machine word in bytes */
    static int wordSize();
    
    /** Get size of pointer in bytes */
    static int pointerSize();
}

// Word type constants
public final class WordConstants {
    /** Maximum unsigned word value */
    public static final UnsignedWord MAX_UNSIGNED;
    
    /** Maximum signed word value */
    public static final SignedWord MAX_SIGNED;
    
    /** Minimum signed word value */
    public static final SignedWord MIN_SIGNED;
    
    /** Word size in bits */
    public static final int WORD_SIZE_BITS;
    
    /** Word size in bytes */
    public static final int WORD_SIZE_BYTES;
}

// Exception types
public class WordException extends RuntimeException {
    public WordException(String message);
    public WordException(String message, Throwable cause);
}