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/*
* Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistribution of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistribution in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
* INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
* MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
* ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
* DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
* DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
* ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
* SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed or intended for use
* in the design, construction, operation or maintenance of any nuclear
* facility.
*
* Sun gratefully acknowledges that this software was originally authored
* and developed by Kenneth Bradley Russell and Christopher John Kline.
*/
package com.sun.gluegen;
import com.sun.gluegen.cgram.types.*;
/** Encapsulates algorithm for laying out data structures. Note that
this ends up embedding code in various places via SizeThunks. If
the 32-bit and 64-bit ports on a given platform differ
fundamentally in their handling of struct layout then this code
will need to be updated and, most likely, two versions of the
SizeThunks maintained in various places. */
public class StructLayout {
private int baseOffset;
private int structAlignment;
protected StructLayout(int baseOffset,
int structAlignment) {
this.baseOffset = baseOffset;
this.structAlignment = structAlignment;
}
public void layout(CompoundType t) {
int n = t.getNumFields();
SizeThunk curOffset = SizeThunk.constant(baseOffset);
SizeThunk maxSize = SizeThunk.constant(0);
for (int i = 0; i < n; i++) {
Field f = t.getField(i);
Type ft = f.getType();
if (ft.isInt() || ft.isFloat() || ft.isDouble() || ft.isPointer()) {
SizeThunk sz = ft.getSize();
curOffset = SizeThunk.roundUp(curOffset, sz);
f.setOffset(curOffset);
if (t.isUnion()) {
maxSize = SizeThunk.max(maxSize, sz);
} else {
curOffset = SizeThunk.add(curOffset, sz);
}
} else if (ft.isCompound()) {
new StructLayout(0, structAlignment).layout(ft.asCompound());
curOffset = SizeThunk.roundUp(curOffset, SizeThunk.constant(structAlignment));
f.setOffset(curOffset);
if (t.isUnion()) {
maxSize = SizeThunk.max(maxSize, ft.getSize());
} else {
curOffset = SizeThunk.add(curOffset, ft.getSize());
}
} else if (ft.isArray()) {
ArrayType arrayType = ft.asArray();
CompoundType compoundElementType = arrayType.getBaseElementType().asCompound();
if (compoundElementType != null) {
new StructLayout(0, structAlignment).layout(compoundElementType);
arrayType.recomputeSize();
}
// Note: not sure how this rounding is done
curOffset = SizeThunk.roundUp(curOffset, SizeThunk.constant(structAlignment));
f.setOffset(curOffset);
curOffset = SizeThunk.add(curOffset, ft.getSize());
} else {
// FIXME
String name = t.getName();
if (name == null) {
name = t.toString();
}
throw new RuntimeException("Complicated field types (" + ft +
" " + f.getName() +
" in type " + name +
") not implemented yet");
}
}
// FIXME: I think the below is wrong; better check with some examples
// if ((curOffset % structAlignment) != 0) {
// curOffset += structAlignment - (curOffset % structAlignment);
// }
if (t.isUnion()) {
t.setSize(maxSize);
} else {
t.setSize(curOffset);
}
}
public static StructLayout createForCurrentPlatform() {
// Note: this code is replicated in CPU.java
String os = System.getProperty("os.name").toLowerCase();
String cpu = System.getProperty("os.arch").toLowerCase();
if ((os.startsWith("windows") && cpu.equals("x86")) ||
(os.startsWith("linux") && cpu.equals("i386")) ||
(os.startsWith("linux") && cpu.equals("amd64")) ||
(os.startsWith("linux") && cpu.equals("x86_64")) ||
(os.startsWith("linux") && cpu.equals("ia64")) ||
(os.startsWith("sunos") && cpu.equals("sparc")) ||
(os.startsWith("sunos") && cpu.equals("x86")) ||
(os.startsWith("sunos") && cpu.equals("amd64")) ||
(os.startsWith("mac os") && cpu.equals("ppc")) ||
(os.startsWith("mac os") && cpu.equals("i386")) ||
(os.startsWith("freebsd") && cpu.equals("i386"))
) {
// FIXME: make struct alignment configurable? May need to change
// packing rules on a per-type basis?
return new StructLayout(0, 8);
} else {
// FIXME: add more ports
throw new RuntimeException("Please port StructLayout to your OS (" + os + ") and CPU (" + cpu + ")");
}
}
}
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