forked from NRZCode/ia32-64
82 lines
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82 lines
3.9 KiB
HTML
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<html xmlns="http://www.w3.org/1999/xhtml" xmlns:svg="http://www.w3.org/2000/svg" xmlns:x86="http://www.felixcloutier.com/x86"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><link rel="stylesheet" type="text/css" href="style.css"></link><title>LDMXCSR
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— Load MXCSR Register</title></head><body><header><nav><ul><li><a href='index.html'>Index</a></li><li>December 2023</li></ul></nav></header><h1>LDMXCSR
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— Load MXCSR Register</h1>
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<table>
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<tr>
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<th>Opcode/Instruction</th>
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<th>Op/En</th>
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<th>64/32-bit Mode</th>
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<th>CPUID Feature Flag</th>
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<th>Description</th></tr>
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<tr>
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<td>NP 0F AE /2 LDMXCSR m32</td>
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<td>M</td>
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<td>V/V</td>
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<td>SSE</td>
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<td>Load MXCSR register from m32.</td></tr>
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<tr>
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<td>VEX.LZ.0F.WIG AE /2 VLDMXCSR m32</td>
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<td>M</td>
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<td>V/V</td>
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<td>AVX</td>
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<td>Load MXCSR register from m32.</td></tr></table>
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<h2 id="instruction-operand-encoding">Instruction Operand Encoding<a class="anchor" href="#instruction-operand-encoding">
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¶
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</a></h2>
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<table>
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<tr>
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<th>Op/En</th>
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<th>Operand 1</th>
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<th>Operand 2</th>
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<th>Operand 3</th>
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<th>Operand 4</th></tr>
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<tr>
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<td>M</td>
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<td>ModRM:r/m (r)</td>
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<td>N/A</td>
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<td>N/A</td>
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<td>N/A</td></tr></table>
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<h2 id="description">Description<a class="anchor" href="#description">
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¶
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</a></h2>
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<p>Loads the source operand into the MXCSR control/status register. The source operand is a 32-bit memory location. See “MXCSR Control and Status Register” in Chapter 10, of the Intel<sup>®</sup> 64 and IA-32 Architectures Software Developer’s Manual, Volume 1, for a description of the MXCSR register and its contents.</p>
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<p>The LDMXCSR instruction is typically used in conjunction with the (V)STMXCSR instruction, which stores the contents of the MXCSR register in memory.</p>
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<p>The default MXCSR value at reset is 1F80H.</p>
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<p>If a (V)LDMXCSR instruction clears a SIMD floating-point exception mask bit and sets the corresponding exception flag bit, a SIMD floating-point exception will not be immediately generated. The exception will be generated only upon the execution of the next instruction that meets both conditions below:</p>
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<ul>
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<li>the instruction must operate on an XMM or YMM register operand,</li>
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<li>the instruction causes that particular SIMD floating-point exception to be reported.</li></ul>
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<p>This instruction’s operation is the same in non-64-bit modes and 64-bit mode.</p>
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<p>If VLDMXCSR is encoded with VEX.L= 1, an attempt to execute the instruction encoded with VEX.L= 1 will cause an #UD exception.</p>
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<p>Note: In VEX-encoded versions, VEX.vvvv is reserved and must be 1111b, otherwise instructions will #UD.</p>
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<h2 id="operation">Operation<a class="anchor" href="#operation">
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¶
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</a></h2>
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<pre>MXCSR := m32;
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</pre>
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<h2 id="c-c++-compiler-intrinsic-equivalent">C/C++ Compiler Intrinsic Equivalent<a class="anchor" href="#c-c++-compiler-intrinsic-equivalent">
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¶
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</a></h2>
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<pre>_mm_setcsr(unsigned int i)
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</pre>
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<h2 class="exceptions" id="numeric-exceptions">Numeric Exceptions<a class="anchor" href="#numeric-exceptions">
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¶
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</a></h2>
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<p>None.</p>
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<h2 class="exceptions" id="other-exceptions">Other Exceptions<a class="anchor" href="#other-exceptions">
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¶
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</a></h2>
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<p>See <span class="not-imported">Table 2-22</span>, “Type 5 Class Exception Conditions,” additionally:</p>
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<table>
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<tr>
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<td>#GP</td>
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<td>For an attempt to set reserved bits in MXCSR.</td></tr>
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<tr>
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<td>#UD</td>
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<td>If VEX.vvvv ≠ 1111B.</td></tr></table><footer><p>
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This UNOFFICIAL, mechanically-separated, non-verified reference is provided for convenience, but it may be
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inc<span style="opacity: 0.2">omp</span>lete or b<sub>r</sub>oke<sub>n</sub> in various obvious or non-obvious
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ways. Refer to <a href="https://software.intel.com/en-us/download/intel-64-and-ia-32-architectures-sdm-combined-volumes-1-2a-2b-2c-2d-3a-3b-3c-3d-and-4">Intel® 64 and IA-32 Architectures Software Developer’s Manual</a> for anything serious.
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</p></footer></body></html>
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