1 /*

     2  * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 package sun.jvm.hotspot.asm.sparc;

    26 

    27 import sun.jvm.hotspot.asm.RTLDataTypes;

    28 

    29 class RegisterDecoder implements /* imports */ RTLDataTypes {

    30     // refer to page 40 - section 5.1.4.1 - Floating-point Register Number Encoding

    31     private static SPARCFloatRegister decodeDouble(int num) {

    32         // 6 bit double precision registers are encoded in 5 bits as

    33         // b<4> b<3> b<2> b<1> b<5>.

    34 

    35         boolean lsb = (0x1 & num) != 0;

    36         if (lsb)

    37             num |= 0x20;  // 10000b

    38 

    39         if ((num % 2) != 0)

    40             return null;

    41 

    42         return SPARCFloatRegisters.getRegister(num);

    43     }

    44 

    45     private static SPARCFloatRegister decodeQuad(int num) {

    46         // 6 bit quad precision registers are encoded in 5 bits as

    47         // b<4> b<3> b<2> 0 b<5>

    48 

    49         boolean lsb = (0x1 & num) != 0;

    50         if (lsb)

    51             num |= 0x20; // 10000b

    52 

    53         if ((num % 4) != 0)

    54             return null;

    55 

    56         return SPARCFloatRegisters.getRegister(num);

    57     }

    58 

    59     static SPARCRegister decode(int dataType, int regNum) {

    60         regNum &= 0x1F; // mask out all but lsb 5 bits

    61         SPARCRegister result = null;

    62         switch (dataType) {

    63             case RTLDT_FL_SINGLE:

    64                 result = SPARCFloatRegisters.getRegister(regNum);

    65                 break;

    66 

    67             case RTLDT_FL_DOUBLE:

    68                 result = decodeDouble(regNum);

    69                 break;

    70 

    71             case RTLDT_FL_QUAD:

    72                 result = decodeQuad(regNum);

    73                 break;

    74 

    75             case RTLDT_UNKNOWN:

    76                 result = null;

    77                 break;

    78 

    79             default: // some integer register

    80                 result = SPARCRegisters.getRegister(regNum);

    81                 break;

    82         }

    83         return result;

    84     }

    85 }