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| <title>FSQRT—Square Root </title></head> |
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| <h1>FSQRT—Square Root</h1> |
| <table> |
| <tr> |
| <th>Opcode</th> |
| <th>Instruction</th> |
| <th>64-Bit Mode</th> |
| <th>Compat/Leg Mode</th> |
| <th>Description</th></tr> |
| <tr> |
| <td>D9 FA</td> |
| <td>FSQRT</td> |
| <td>Valid</td> |
| <td>Valid</td> |
| <td>Computes square root of ST(0) and stores the result in ST(0).</td></tr></table> |
| <h2>Description</h2> |
| <p>Computes the square root of the source value in the ST(0) register and stores the result in ST(0).</p> |
| <p>The following table shows the results obtained when taking the square root of various classes of numbers, assuming that neither overflow nor underflow occurs.</p> |
| <h3>Table 3-47. FSQRT Results</h3> |
| <table> |
| <tr> |
| <th>SRC (ST(0))</th> |
| <th>DEST (ST(0))</th></tr> |
| <tr> |
| <td>− ∞</td> |
| <td>*</td></tr> |
| <tr> |
| <td>− F</td> |
| <td>*</td></tr> |
| <tr> |
| <td>− 0</td> |
| <td>− 0</td></tr> |
| <tr> |
| <td>+ 0</td> |
| <td>+ 0</td></tr> |
| <tr> |
| <td>+ F</td> |
| <td>+ F</td></tr> |
| <tr> |
| <td>+ ∞</td> |
| <td>+ ∞</td></tr> |
| <tr> |
| <td>NaN</td> |
| <td>NaN</td></tr></table> |
| <p><strong>NOTES:</strong></p> |
| <p>F Means finite floating-point value.</p> |
| <p>*</p> |
| <p>Indicates floating-point invalid-arithmetic-operand (#IA) exception.</p> |
| <p>This instruction’s operation is the same in non-64-bit modes and 64-bit mode.</p> |
| <h2>Operation</h2> |
| <pre>ST(0) ← SquareRoot(ST(0));</pre> |
| <h2>FPU Flags Affected</h2> |
| <table class="exception-table"> |
| <tr> |
| <td>C1</td> |
| <td> |
| <p>Set to 0 if stack underflow occurred.</p> |
| <p>Set if result was rounded up; cleared otherwise.</p></td></tr> |
| <tr> |
| <td>C0, C2, C3</td> |
| <td>Undefined.</td></tr></table> |
| <h2>Floating-Point Exceptions</h2> |
| <table class="exception-table"> |
| <tr> |
| <td>#IS</td> |
| <td>Stack underflow occurred.</td></tr> |
| <tr> |
| <td>#IA</td> |
| <td> |
| <p>Source operand is an SNaN value or unsupported format.</p> |
| <p>Source operand is a negative value (except for −0).</p></td></tr></table> |
| <p>#D</p> |
| <p>Source operand is a denormal value.</p> |
| <p>#P</p> |
| <p>Value cannot be represented exactly in destination format.</p> |
| <h2>Protected Mode Exceptions</h2> |
| <table class="exception-table"> |
| <tr> |
| <td>#NM</td> |
| <td>CR0.EM[bit 2] or CR0.TS[bit 3] = 1.</td></tr> |
| <tr> |
| <td>#MF</td> |
| <td>If there is a pending x87 FPU exception.</td></tr> |
| <tr> |
| <td>#UD</td> |
| <td>If the LOCK prefix is used.</td></tr></table> |
| <h2>Real-Address Mode Exceptions</h2> |
| <p>Same exceptions as in protected mode.</p> |
| <h2>Virtual-8086 Mode Exceptions</h2> |
| <p>Same exceptions as in protected mode.</p> |
| <h2>Compatibility Mode Exceptions</h2> |
| <p>Same exceptions as in protected mode.</p> |
| <h2>64-Bit Mode Exceptions</h2> |
| <p>Same exceptions as in protected mode.</p></body></html> |