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| <head> |
| <title>aget<kind></title> |
| <link rel=stylesheet href="opcode.css"> |
| </head> |
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| <body> |
| |
| <h1>aget<kind></h1> |
| |
| <h2>Purpose</h2> |
| |
| <p> |
| Perform the identified array operation at the identified index of the given |
| array, storing into the value register. |
| </p> |
| |
| <h2>Details</h2> |
| |
| <table class="instruc"> |
| <thead> |
| <tr> |
| <th>Op & Format</th> |
| <th>Mnemonic / Syntax</th> |
| <th>Arguments</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td>44..51 23x</td> |
| <td><i>arrayop</i> vAA, vBB, vCC<br/> |
| 44: aget<br/> |
| 45: aget-wide<br/> |
| 46: aget-object<br/> |
| 47: aget-boolean<br/> |
| 48: aget-byte<br/> |
| 49: aget-char<br/> |
| 4a: aget-short<br/> |
| </td> |
| <td><code>A:</code> dest value register or pair; (8 bits)<br/> |
| <code>B:</code> array register (8 bits)<br/> |
| <code>C:</code> index register (8 bits)</td> |
| </tr> |
| </tbody> |
| </table> |
| |
| <h2>Constraints</h2> |
| |
| <ul> |
| <li> |
| A, B and C must be valid register indices in the current stackframe. |
| </li> |
| <li> |
| For the aget-wide variant, also A+1 must be a valid register index in the |
| current stackframe. |
| </li> |
| <li> |
| Register vB must contain an array reference. The component type of the |
| array must match the variant of the instruction. |
| </li> |
| <li> |
| Register vC must contain an integer value. |
| </li> |
| </ul> |
| |
| <h2>Behavior</h2> |
| |
| <ul> |
| <li> |
| For all but the -wide variant, the array element at the given index is moved |
| into register vA, that is, vA'=array[index]. |
| </li> |
| <li> |
| For the -wide variant, the array element at the given index is moved into |
| registers vA and v(A+1) as follows: |
| <ul> |
| <li> |
| vA'=array[index] >> 0x20 |
| </li> |
| <li> |
| v(A+1)'=array[index] & 0xffffffff; |
| </li> |
| </ul> |
| </li> |
| <li> |
| If v(A-1) is the lower half of a register pair, v(A-1)' becomes undefined. |
| </li> |
| <li> |
| For all but the -wide variant, if v(A+1) is the upper half of a register |
| pair, v(A+1)' becomes undefined. |
| </li> |
| <li> |
| For the -wide variant, if v(A+2) is the upper half of a register pair, |
| v(A+2)' becomes undefined. |
| </li> |
| </ul> |
| |
| <h2>Exceptions</h2> |
| |
| <ul> |
| <li> |
| NullPointerException if vB=null. |
| </li> |
| <li> |
| ArrayIndexOutOfBoundsException if vC < 0 or vC >= array.length. |
| </li> |
| </ul> |
| |
| </body> |
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