"
COPYRIGHT (c) 1995 by Claus Gittinger
All Rights Reserved
This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice. This software may not
be provided or otherwise made available to, or used by, any
other person. No title to or ownership of the software is
hereby transferred.
"
"{ Package: 'stx:libbasic' }"
Object subclass:#ExternalAddress
instanceVariableNames:'address*'
classVariableNames:''
poolDictionaries:''
category:'System-Support'
!
!ExternalAddress class methodsFor:'documentation'!
copyright
"
COPYRIGHT (c) 1995 by Claus Gittinger
All Rights Reserved
This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice. This software may not
be provided or otherwise made available to, or used by, any
other person. No title to or ownership of the software is
hereby transferred.
"
!
documentation
"
Instances of this class represent external (non-Smalltalk) addresses.
They are only useful to represent handles as returned by C functions
as smalltalk objects. For example, Window- or WidgetIDs (which are actually
32 bit pointers) should be represented this way.
(you should not use SmallIntegers for this, since they can only represent 31
bits; LargeIntegers could be used in theory, but it is not a very good style
to do so, since it makes things a bit cryptic - having ExternalAddresses
around makes things pretty clear in inspectors etc.).
There is not much you can do with ExternalAddresses on the smalltalk level;
creation/use is mostly in primitive C-code via
__MKEXTERNALADDRESS(voidPtr) and __ExternalAddressVal(obj).
ExternallAddresses are much like ExternalBytes - however, the latter
allow you to access bytes via indexed at:/at:put: messages.
ExternalAddresses do not allow such accesses (they are meant to remain
anonymous).
[author:]
Claus Gittinger
[see also:]
ByteArray
ExternalBytes ExternalFunction
( how to write primitive code :html: programming/primitive.html )
"
!
examples
"
To pass some C-pointer from primitive code to smalltalk:
...
RETURN (__MKEXTERNALADDRESS(foo));
pass it back to C and use it there:
...
if (__isExternalAddress(anExternalAddress)) {
ptr = __externalAddressVal(anExternalAddress));
}
...
concrete example:
test1
%{
static char foo[] = {'h', 'e' ,'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '\n'};
RETURN (__MKEXTERNALADDRESS(foo));
%}
test2:anExternalAddress
%{
if (__isExternalAddress(anExternalAddress)) {
printf(__externalAddressVal(anExternalAddress));
RETURN (self);
}
%}
"
! !
!ExternalAddress class methodsFor:'instance creation'!
newAddress:addr
^ self new setAddress:addr
! !
!ExternalAddress class methodsFor:'queries'!
isBuiltInClass
"return true if this class is known by the run-time-system.
Here, true is returned."
^ self == ExternalAddress
"Modified: / 11.6.1998 / 17:12:40 / cg"
!
pointerSize
"answer the size in bytes of a pointer"
%{ /* NOCONTEXT */
RETURN(__mkSmallInteger(sizeof(void *)));
%}.
"
self pointerSize
"
! !
!ExternalAddress methodsFor:'accessing'!
address
"return the start address as an integer"
%{ /* NOCONTEXT */
unsigned INT addr;
addr = (unsigned INT)__INST(address_);
RETURN ( __MKUINT(addr));
%}
!
instVarAt:index
"redefined to suppress direct access to my address, which is a non-object"
index == 1 ifTrue:[
^ self address
].
^ super instVarAt:index
"Created: / 3.9.1999 / 13:47:03 / ps"
!
instVarAt:index put:newAddress
"redefined to suppress direct access to my address, which is a non-object"
index == 1 ifTrue:[
self setAddress:newAddress.
^ newAddress
].
^ super instVarAt:index put:newAddress
"Created: / 3.9.1999 / 14:31:57 / ps"
! !
!ExternalAddress methodsFor:'comparing'!
= anExternalAddress
"return true, if two externalAddress instance represent the same
C pointer"
%{ /* NOCONTEXT */
if (__isExternalAddress(anExternalAddress)
&& (__externalAddressVal(self) == __externalAddressVal(anExternalAddress))) {
RETURN (true);
}
%}.
^ false
!
hash
"return a number useful for hashing"
%{ /* NOCONTEXT */
unsigned INT addr = (unsigned INT) __externalAddressVal(self);
if (addr > _MAX_INT) {
if ((addr & 1) == 0) {
addr >>= 1;
}
if (addr > _MAX_INT) {
if ((addr & 1) == 0) {
addr >>= 1;
}
}
if (addr > _MAX_INT) {
addr &= _MAX_INT;
}
} else {
addr <<= 1;
if (addr <= _MAX_INT) {
addr <<= 1;
if (addr <= _MAX_INT) {
addr <<= 1;
}
}
addr >>= 1;
}
RETURN (__MKSMALLINT(addr));
%}
! !
!ExternalAddress methodsFor:'converting'!
asExternalAddress
"convert to an ExternalAddress.
Useful to convert subclasses"
%{ /* NOCONTEXT */
if (__qClass(self) == @global(ExternalAddress)) {
RETURN(self)
}
RETURN(__MKEXTERNALADDRESS(__INST(address_)));
%}.
"
(ExternalAddress newAddress:16r12345678) asExternalAddress
"
!
asExternalBytes
"return an ExternalBytes object pointing to where the receiver points to.
Use of this is not recommended; primitives which return externalAddresses
dont think that access to the memory is required/useful, while primitives
which do think so should return an externalBytes instance right away."
%{ /* NOCONTEXT */
RETURN(__MKEXTERNALBYTES(__INST(address_)));
%}
"
(ExternalAddress newAddress:16r12345678) asExternalBytes
"
! !
!ExternalAddress methodsFor:'printing & storing'!
printOn:aStream
"return a printed representation of the receiver"
self class name printOn:aStream.
aStream nextPutAll:' at:'.
self address printOn:aStream base:16.
! !
!ExternalAddress methodsFor:'private accessing'!
setAddress:anInteger
"set the address"
%{ /* NOCONTEXT */
unsigned INT addr;
if (__isSmallInteger(anInteger)) {
addr = __intVal(anInteger);
} else {
addr = __longIntVal(anInteger);
}
__INST(address_) = (OBJ)addr;
%}
! !
!ExternalAddress class methodsFor:'documentation'!
version
^ '$Header: /cvs/stx/stx/libbasic/ExternalAddress.st,v 1.17 2003-02-09 15:48:59 stefan Exp $'
! !