/*
* $Id$
*
* Copyright (C) 2003-2015 JNode.org
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.jnode.vm.x86.compiler.l1b;
import org.jnode.assembler.x86.X86Register;
import org.jnode.assembler.x86.X86Register.FPU;
import org.jnode.vm.bytecode.StackException;
/**
* @author Ewout Prangsma (epr@users.sourceforge.net)
*/
final class FPUStack extends ItemStack {
private static final FPU[] REGS = {X86Register.ST0, X86Register.ST1,
X86Register.ST2, X86Register.ST3, X86Register.ST4, X86Register.ST5,
X86Register.ST6, X86Register.ST7};
/**
* Initialize this instance.
*/
FPUStack() {
super(Item.Kind.FPUSTACK, REGS.length);
}
/**
* Gets the FPU register that contains the given item.
*
* @param item
* @return
* @see org.jnode.assembler.x86.X86Register#ST1
*/
final FPU getRegister(Item item) {
for (int i = 0; i < tos; i++) {
if (stack[tos - (i + 1)] == item) {
return REGS[i];
}
}
throw new StackException("Item not found on FPU stack");
}
/**
* Gets the item that is contained in the given register.
*/
final Item getItem(FPU fpuReg) {
final int idx = tos - (fpuReg.getNr() + 1);
return stack[idx];
}
/**
* Swap the top of the stack (ST0) with the given FPU reg.
*
* @param fpuReg
*/
final void fxch(FPU fpuReg) {
final int idx1 = tos - 1;
final int idx2 = tos - (fpuReg.getNr() + 1);
final Item tmp = stack[idx1];
stack[idx1] = stack[idx2];
stack[idx2] = tmp;
}
}