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1 /*
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2 * Copyright 2002 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.asm.sparc;
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26
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27 import sun.jvm.hotspot.asm.RTLDataTypes;
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28
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29 class RegisterDecoder implements /* imports */ RTLDataTypes {
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30 // refer to page 40 - section 5.1.4.1 - Floating-point Register Number Encoding
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31 private static SPARCFloatRegister decodeDouble(int num) {
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32 // 6 bit double precision registers are encoded in 5 bits as
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33 // b<4> b<3> b<2> b<1> b<5>.
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34
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35 boolean lsb = (0x1 & num) != 0;
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36 if (lsb)
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37 num |= 0x20; // 10000b
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38
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39 if ((num % 2) != 0)
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40 return null;
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41
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42 return SPARCFloatRegisters.getRegister(num);
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43 }
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44
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45 private static SPARCFloatRegister decodeQuad(int num) {
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46 // 6 bit quad precision registers are encoded in 5 bits as
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47 // b<4> b<3> b<2> 0 b<5>
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48
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49 boolean lsb = (0x1 & num) != 0;
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50 if (lsb)
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51 num |= 0x20; // 10000b
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52
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53 if ((num % 4) != 0)
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54 return null;
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55
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56 return SPARCFloatRegisters.getRegister(num);
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57 }
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58
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59 static SPARCRegister decode(int dataType, int regNum) {
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60 regNum &= 0x1F; // mask out all but lsb 5 bits
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61 SPARCRegister result = null;
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62 switch (dataType) {
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63 case RTLDT_FL_SINGLE:
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64 result = SPARCFloatRegisters.getRegister(regNum);
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65 break;
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66
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67 case RTLDT_FL_DOUBLE:
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68 result = decodeDouble(regNum);
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69 break;
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70
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71 case RTLDT_FL_QUAD:
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72 result = decodeQuad(regNum);
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73 break;
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74
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75 case RTLDT_UNKNOWN:
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76 result = null;
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77 break;
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78
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79 default: // some integer register
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80 result = SPARCRegisters.getRegister(regNum);
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81 break;
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82 }
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83 return result;
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84 }
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85 }
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