javax.realtime.device

Interface RawByteReader

All Superinterfaces:

RawMemory

All Known Subinterfaces:

RawByte

public interface RawByteReader
extends RawMemory

A marker for a byte accessor object encapsulating the protocol for reading bytes from raw memory. A byte accessor can always access at least one byte. Each byte is transferred in a single atomic operation. Groups of bytes may be transferred together; however, this is not required.

Objects of this type are created with the method RawMemoryFactory.createRawByteReader(javax.realtime.device.RawMemoryRegion, long, int, int) and RawMemoryFactory.createRawByte(javax.realtime.device.RawMemoryRegion, long, int, int). Each object references a range of elements in the RawMemoryRegion starting at the base address provided to the factory method. The size provided to the factory method determines the number of accessible elements.

Caching of the memory access is controlled by the factory that created this object. If the memory is not cached, this method guarantees serialized access. In other words, the memory access at the memory occurs in the same order as in the program. Multiple writes to the same location may not be coalesced.

Since:

RTSJ 2.0

Method Summary

Modifier and Type	Method and Description
int	get(int offset, byte[] values) Fills values with elements from this instance, where the nth element is at the address base address + (offset + n) × stride × element size in bytes.
int	get(int offset, byte[] values, int start, int count) Fills values from index start with elements from this instance, where the nth element is at the address base address + (offset + n) × stride × element size in bytes.
byte	getByte() Gets the value at the first position referenced by this instance, i.e., the value at its start address.
byte	getByte(int offset) Gets the value at the address represented by offset from the base of this instance: base address + (offset × stride × element size in bytes).

Methods inherited from interface javax.realtime.device.RawMemory

getAddress, getSize, getStride

Method Detail

getByte

byte getByte()

Gets the value at the first position referenced by this instance, i.e., the value at its start address. This operation must be atomic with respect to all other raw memory accesses to the address.

Returns:

the value at the base address.

getByte

byte getByte(int offset)
      throws OffsetOutOfBoundsException

Gets the value at the address represented by offset from the base of this instance: base address + (offset × stride × element size in bytes). When an exception is thrown, no data is transferred.

Parameters:

offset - of byte in the memory region starting from the address specified in the associated factory method.

Returns:

the value at the address specified.

Throws:

OffsetOutOfBoundsException - when offset is negative or greater than or equal to the number of elements in the raw memory region.

get

int get(int offset,
        byte[] values)
 throws OffsetOutOfBoundsException,
        java.lang.NullPointerException

Fills values with elements from this instance, where the n^th element is at the address base address + (offset + n) × stride × element size in bytes. Only the bytes in the intersection of the start and end of values and the base address and the end of the memory region are transferred. When an exception is thrown, no data is transferred.

Parameters:

offset - of the first byte in the memory region to transfer.

values - The array to receive the bytes.

Returns:

the number of elements actually transferred to values.

Throws:

OffsetOutOfBoundsException - when offset is negative or greater than or equal to the number of elements in the raw memory region.

java.lang.NullPointerException - when values is null.

get

int get(int offset,
        byte[] values,
        int start,
        int count)
 throws OffsetOutOfBoundsException,
        java.lang.ArrayIndexOutOfBoundsException,
        java.lang.IllegalArgumentException,
        java.lang.NullPointerException

Fills values from index start with elements from this instance, where the n^th element is at the address base address + (offset + n) × stride × element size in bytes. The number of bytes transferred is the minimum of count, the size of the memory region minus offset, and length of values minus start. When an exception is thrown, no data is transferred.

Parameters:

offset - of the first byte in the memory region to transfer.

values - The array to receive the bytes.

start - The first index in array to fill.

count - The maximum number of bytes to copy.

Returns:

the number of bytes actually transferred.

Throws:

OffsetOutOfBoundsException - when offset is negative or either offset or offset + count is greater than or equal to the size of this raw memory area.

java.lang.ArrayIndexOutOfBoundsException - when start is negative or either start or start + count is greater than or equal to the size of values.

java.lang.NullPointerException - when values is null or count is negative.

java.lang.IllegalArgumentException