Package jnr.ffi.byref

Class NumberByReference

java.lang.Object

java.lang.Number

jnr.ffi.byref.AbstractNumberReference<java.lang.Number>

jnr.ffi.byref.NumberByReference

All Implemented Interfaces:

java.io.Serializable, ByReference<java.lang.Number>

public class NumberByReference
extends AbstractNumberReference<java.lang.Number>

NumberByReference is used when the address of a primitive integral value must be passed as a parameter to a function, but the exact type is system dependent.

For example, the following C code,

 

 extern void get_size(ssize_t *sp);

 ssize_t foo(void) {
     ssize_t n;
     // pass a reference to 'n' so get_size() can fill it out
     get_size(&n);

     return n;
 }
 
 

Would be declared in java as

 

 interface Lib {
     void get_size(@Out NumberByReference ap);
 }

 
 

and used like this

 

 NumberByReference size = new NumberByReference(ssize_t);
 lib.get_size(size);
 System.out.printf("size from lib=%d\n", size.longValue());

 
 

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
NumberByReference(TypeAlias typeAlias)
NumberByReference(TypeAlias typeAlias, java.lang.Number value)

Method Summary

Modifier and Type	Method	Description
void	fromNative(Runtime runtime, Pointer memory, long offset)	Copies the java value from native memory
int	nativeSize(Runtime runtime)	Gets the size of the native buffer required to store the value
void	toNative(Runtime runtime, Pointer memory, long offset)	Copies the java value to native memory

Methods inherited from class jnr.ffi.byref.AbstractNumberReference

byteValue, checkNull, doubleValue, floatValue, getValue, intValue, longValue, shortValue

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NumberByReference

public NumberByReference(TypeAlias typeAlias,
                         java.lang.Number value)

NumberByReference

public NumberByReference(TypeAlias typeAlias)

Method Detail

nativeSize

public int nativeSize(Runtime runtime)

Description copied from interface: ByReference

Gets the size of the native buffer required to store the value

Parameters:

runtime - The current runtime.

Returns:

the size in bytes of the native type

fromNative

public void fromNative(Runtime runtime,
                       Pointer memory,
                       long offset)

Description copied from interface: ByReference

Copies the java value from native memory

Parameters:

runtime - The current runtime.

memory - the native memory buffer.

offset - The offset of the field.

toNative

public void toNative(Runtime runtime,
                     Pointer memory,
                     long offset)

Description copied from interface: ByReference

Copies the java value to native memory

Parameters:

runtime - The current runtime.

memory - The native memory buffer.

offset - The offset of the field.