242 lines
10 KiB
Java
242 lines
10 KiB
Java
package club.doki7.ffm.ptr;
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import club.doki7.ffm.IPointer;
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import club.doki7.ffm.annotation.Unsafe;
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import club.doki7.ffm.annotation.UnsafeConstructor;
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import club.doki7.ffm.annotation.ValueBasedCandidate;
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import org.jetbrains.annotations.NotNull;
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import org.jetbrains.annotations.Nullable;
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import java.lang.foreign.Arena;
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import java.lang.foreign.MemorySegment;
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import java.lang.foreign.ValueLayout;
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import java.nio.Buffer;
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import java.nio.ShortBuffer;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import java.util.NoSuchElementException;
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/// Represents a pointer to 16-bit short integer(s) in native memory.
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///
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/// The property {@link #segment()} should always be not-null
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/// ({@code segment != NULL && !segment.equals(MemorySegment.NULL)}), and properly aligned to
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/// {@link ValueLayout.OfShort#byteAlignment()} bytes. To represent null pointer, you may use a Java
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/// {@code null} instead. See the documentation of {@link IPointer#segment()} for more details.
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///
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/// The constructor of this class is marked as {@link UnsafeConstructor}, because it does not
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/// perform any runtime check. The constructor can be useful for automatic code generators. For
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/// normal users, {@link #checked(MemorySegment)} is a good safe alternative.
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@ValueBasedCandidate
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@UnsafeConstructor
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public record ShortPtr(@NotNull MemorySegment segment) implements IPointer, Iterable<Short> {
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public long size() {
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return segment.byteSize() / Short.BYTES;
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}
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public short read() {
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return segment.get(ValueLayout.JAVA_SHORT, 0);
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}
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public void write(short value) {
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segment.set(ValueLayout.JAVA_SHORT, 0, value);
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}
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public short read(long index) {
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return segment.get(ValueLayout.JAVA_SHORT, index * Short.BYTES);
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}
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public void write(long index, short value) {
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segment.set(ValueLayout.JAVA_SHORT, index * Short.BYTES, value);
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}
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public void write(short @NotNull [] values) {
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segment.copyFrom(MemorySegment.ofArray(values));
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}
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public void writeV(short value0, short @NotNull ...values) {
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write(value0);
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offset(1).write(values);
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}
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/// Assume the {@link ShortPtr} is capable of holding at least {@code newSize} short integers,
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/// create a new view {@link ShortPtr} that uses the same backing storage as this
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/// {@link ShortPtr}, but with the new size. Since there is actually no way to really check
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/// whether the new size is valid, while buffer overflow is undefined behavior, this method is
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/// marked as {@link Unsafe}.
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///
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/// This method could be useful when handling data returned from some C API, where the size of
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/// the data is not known in advance.
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///
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/// If the size of the underlying segment is actually known in advance and correctly set, and
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/// you want to create a shrunk view, you may use {@link #slice(long)} (with validation)
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/// instead.
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@Unsafe
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public @NotNull ShortPtr reinterpret(long newSize) {
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return new ShortPtr(segment.reinterpret(newSize * Short.BYTES));
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}
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public @NotNull ShortPtr offset(long offset) {
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return new ShortPtr(segment.asSlice(offset * Short.BYTES));
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}
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/// Note that this function uses the {@link List#subList(int, int)} semantics (left inclusive,
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/// right exclusive interval), not {@link MemorySegment#asSlice(long, long)} semantics
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/// (offset + newSize). Be careful with the difference.
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public @NotNull ShortPtr slice(long start, long end) {
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return new ShortPtr(segment.asSlice(start * Short.BYTES, (end - start) * Short.BYTES));
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}
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public @NotNull ShortPtr slice(long end) {
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return new ShortPtr(segment.asSlice(0, end * Short.BYTES));
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}
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@Override
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public @NotNull Iterator<Short> iterator() {
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return new Iter(segment);
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}
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/// Create a new {@link ShortPtr} using {@code segment} as backing storage, with argument
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/// validation.
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///
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/// This function does not ensure {@code segment}'s size to be a multiple of
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/// {@link Short#BYTES}, since that several trailing bytes could be automatically ignored by
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/// {@link #size()} method, and usually these bytes does not interfere with FFI operations.
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/// If {@code segment} is not big enough to hold at least one short integer, that segment is
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/// simply considered "empty". See the documentation of {@link IPointer#segment()} for more
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/// details.
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///
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/// @param segment the {@link MemorySegment} to use as the backing storage
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/// @return {@code null} if {@code segment} is {@link MemorySegment#NULL},
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/// otherwise a new {@link ShortPtr} that uses {@code segment} as backing storage
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/// @throws IllegalArgumentException if {@code segment} is not native or not properly aligned
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public static @Nullable ShortPtr checked(@NotNull MemorySegment segment) {
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if (segment.equals(MemorySegment.NULL)) {
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return null;
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}
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if (!segment.isNative()) {
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throw new IllegalArgumentException("Segment must be native");
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}
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if (segment.address() % ValueLayout.JAVA_SHORT.byteAlignment() != 0) {
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throw new IllegalArgumentException("Segment address must be aligned to " + ValueLayout.JAVA_SHORT.byteAlignment() + " bytes");
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}
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return new ShortPtr(segment);
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}
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/// Create a new {@link ShortPtr} using the same backing storage as {@code buffer}, with
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/// argument validation.
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///
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/// The main difference between this static method and the {@link #allocate(Arena, ShortBuffer)}
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/// method is that this method does not copy the contents of {@code buffer} into a newly
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/// allocated {@link MemorySegment}. Instead, the newly created {@link ShortPtr} will use the
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/// same backing storage as {@code buffer}. Thus, modifications from one side will be visible on
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/// the other side.
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///
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/// Be careful with {@link java.nio} buffer types' {@link Buffer#position()} property: only the
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/// "remaining" (from {@link Buffer#position()} to {@link Buffer#limit()}) part of
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/// {@code buffer} will be referred. If you have ever read from {@code buffer}, and you want all
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/// the contents of {@code buffer} to be referred, you may want to call {@link Buffer#rewind()}.
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///
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/// When handling data types consisting of multiple bytes, also be careful with endianness and
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/// {@link ShortBuffer#order()} property. {@link ShortPtr} always uses the native endianness. So
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/// if {@code buffer} uses a different endianness, you may want to convert it to the native
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/// endianness first.
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///
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/// @param buffer the {@link ShortBuffer} to use as the backing storage
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/// @return a new {@link ShortPtr} that uses {@code buffer} as its backing storage
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/// @throws IllegalArgumentException if {@code buffer} is not direct, or its backing storage is
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/// not properly aligned
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public static @NotNull ShortPtr checked(@NotNull ShortBuffer buffer) {
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if (!buffer.isDirect()) {
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throw new IllegalArgumentException("Buffer must be direct");
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}
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MemorySegment segment = MemorySegment.ofBuffer(buffer);
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if (segment.address() % ValueLayout.JAVA_SHORT.byteAlignment() != 0) {
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throw new IllegalArgumentException("Buffer address must be aligned to " + ValueLayout.JAVA_SHORT.byteAlignment() + " bytes");
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}
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return new ShortPtr(segment);
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}
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public static @NotNull ShortPtr allocate(@NotNull Arena arena) {
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return new ShortPtr(arena.allocate(ValueLayout.JAVA_SHORT));
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}
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public static @NotNull ShortPtr allocate(@NotNull Arena arena, long size) {
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return new ShortPtr(arena.allocate(ValueLayout.JAVA_SHORT, size));
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}
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public static @NotNull ShortPtr allocate(@NotNull Arena arena, short @NotNull [] array) {
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return new ShortPtr(arena.allocateFrom(ValueLayout.JAVA_SHORT, array));
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}
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public static @NotNull ShortPtr allocate(@NotNull Arena arena, Collection<Short> shorts) {
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ShortPtr ret = allocate(arena, shorts.size());
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int i = 0;
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for (Short value : shorts) {
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ret.write(i, value);
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i += 1;
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}
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return ret;
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}
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public static @NotNull ShortPtr allocateV(@NotNull Arena arena, short value0, short ...values) {
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ShortPtr ret = allocate(arena, values.length + 1);
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ret.write(value0);
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ret.offset(1).segment.copyFrom(MemorySegment.ofArray(values));
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return ret;
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}
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/// Allocate a new {@link ShortPtr} in {@code arena} and copy the contents of {@code buffer} into
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/// the newly allocated {@link ShortPtr}.
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///
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/// Be careful with {@link java.nio} buffer types' {@link Buffer#position()} property: only the
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/// "remaining" (from {@link Buffer#position()} to {@link Buffer#limit()}) part of
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/// {@code buffer} will be copied. If you have ever read from {@code buffer}, and you want all
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/// the contents of {@code buffer} to be copied, you may want to call {@link Buffer#rewind()}.
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///
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/// When handling data types consisting of multiple bytes, also be careful with endianness and
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/// {@link ShortBuffer#order()} property. {@link ShortPtr} always uses the native endianness. So
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/// if {@code buffer} uses a different endianness, you may want to convert it to the native
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/// endianness first.
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///
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/// @param arena the {@link Arena} to allocate the new {@link ShortPtr} in
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/// @param buffer the {@link ShortBuffer} to copy the contents from
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/// @return a new {@link ShortPtr} that contains the contents of {@code buffer}
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public static @NotNull ShortPtr allocate(@NotNull Arena arena, @NotNull ShortBuffer buffer) {
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MemorySegment s = arena.allocate(ValueLayout.JAVA_SHORT, buffer.remaining());
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s.copyFrom(MemorySegment.ofBuffer(buffer));
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return new ShortPtr(s);
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}
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/// An iterator over the short integers.
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private static final class Iter implements Iterator<Short> {
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Iter(@NotNull MemorySegment segment) {
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this.segment = segment;
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}
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@Override
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public boolean hasNext() {
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return segment.byteSize() >= Short.BYTES;
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}
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@Override
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public Short next() {
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if (!hasNext()) {
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throw new NoSuchElementException("No more short integers to read");
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}
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short value = segment.get(ValueLayout.JAVA_SHORT, 0);
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segment = segment.asSlice(Short.BYTES);
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return value;
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}
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private @NotNull MemorySegment segment;
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}
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}
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