1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 2 3 <html> 4 5 <head> 6 <title>aget<kind></title> 7 <link rel=stylesheet href="opcode.css"> 8 </head> 9 10 <body> 11 12 <h1>aget<kind></h1> 13 14 <h2>Purpose</h2> 15 16 <p> 17 Perform the identified array operation at the identified index of the given 18 array, storing into the value register. 19 </p> 20 21 <h2>Details</h2> 22 23 <table class="instruc"> 24 <thead> 25 <tr> 26 <th>Op & Format</th> 27 <th>Mnemonic / Syntax</th> 28 <th>Arguments</th> 29 </tr> 30 </thead> 31 <tbody> 32 <tr> 33 <td>44..51 23x</td> 34 <td><i>arrayop</i> vAA, vBB, vCC<br/> 35 44: aget<br/> 36 45: aget-wide<br/> 37 46: aget-object<br/> 38 47: aget-boolean<br/> 39 48: aget-byte<br/> 40 49: aget-char<br/> 41 4a: aget-short<br/> 42 </td> 43 <td><code>A:</code> dest value register or pair; (8 bits)<br/> 44 <code>B:</code> array register (8 bits)<br/> 45 <code>C:</code> index register (8 bits)</td> 46 </tr> 47 </tbody> 48 </table> 49 50 <h2>Constraints</h2> 51 52 <ul> 53 <li> 54 A, B and C must be valid register indices in the current stackframe. 55 </li> 56 <li> 57 For the aget-wide variant, also A+1 must be a valid register index in the 58 current stackframe. 59 </li> 60 <li> 61 Register vB must contain an array reference. The component type of the 62 array must match the variant of the instruction. 63 </li> 64 <li> 65 Register vC must contain an integer value. 66 </li> 67 </ul> 68 69 <h2>Behavior</h2> 70 71 <ul> 72 <li> 73 For all but the -wide variant, the array element at the given index is moved 74 into register vA, that is, vA'=array[index]. 75 </li> 76 <li> 77 For the -wide variant, the array element at the given index is moved into 78 registers vA and v(A+1) as follows: 79 <ul> 80 <li> 81 vA'=array[index] >> 0x20 82 </li> 83 <li> 84 v(A+1)'=array[index] & 0xffffffff; 85 </li> 86 </ul> 87 </li> 88 <li> 89 If v(A-1) is the lower half of a register pair, v(A-1)' becomes undefined. 90 </li> 91 <li> 92 For all but the -wide variant, if v(A+1) is the upper half of a register 93 pair, v(A+1)' becomes undefined. 94 </li> 95 <li> 96 For the -wide variant, if v(A+2) is the upper half of a register pair, 97 v(A+2)' becomes undefined. 98 </li> 99 </ul> 100 101 <h2>Exceptions</h2> 102 103 <ul> 104 <li> 105 NullPointerException if vB=null. 106 </li> 107 <li> 108 ArrayIndexOutOfBoundsException if vC < 0 or vC >= array.length. 109 </li> 110 </ul> 111 112 </body> 113 </html> 114
