4:162
Volume 4: Base IA-32 Instruction Reference
FSAVE/FNSAVE—Store FPU State
Description
Stores the current FPU state (operating environment and register stack) at the specified
destination in memory, and then re-initializes the FPU. The FSAVE instruction checks for
and handles pending unmasked floating-point exceptions before storing the FPU state;
the FNSAVE instruction does not.
The FPU operating environment consists of the FPU control word, status word, tag
word, instruction pointer, data pointer, and last opcode. See the
Intel
®
64 and IA-32
Architectures Software Developer’s Manual
for the layout in memory of the stored
environment, depending on the operating mode of the processor (protected or real)
and the size of the current address attribute (16-bit or 32-bit). In virtual-8086 mode,
the real mode layouts are used. The contents of the FPU register stack are stored in the
80 bytes immediately follow the operating environment image.
The saved image reflects the state of the FPU after all floating-point instructions
preceding the FSAVE/FNSAVE instruction in the instruction stream have been executed.
After the FPU state has been saved, the FPU is reset to the same default values it is set
to with the FINIT/FNINIT instructions (see
“FINIT/FNINIT—Initialize Floating-point Unit”
).
The FSAVE/FNSAVE instructions are typically used when the operating system needs to
perform a context switch, an exception handler needs to use the FPU, or an application
program needs to pass a “clean” FPU to a procedure.
Operation
(* Save FPU State and Registers *)
DEST(FPUControlWord)
FPUControlWord;
DEST(FPUStatusWord)
FPUStatusWord;
DEST(FPUTagWord)
FPUTagWord;
DEST(FPUDataPointer)
FPUDataPointer;
DEST(FPUInstructionPointer)
FPUInstructionPointer;
DEST(FPULastInstructionOpcode)
FPULastInstructionOpcode;
DEST(ST(0))
ST(0);
DEST(ST(1))
ST(1);
DEST(ST(2))
ST(2);
DEST(ST(3))
ST(3);
DEST(ST(4))
ST(4);
DEST(ST(5))
ST(5);
DEST(ST(6))
ST(6);
DEST(ST(7))
ST(7);
(* Initialize FPU *)
FPUControlWord
037FH;
Opcode
Instruction
Description
9B DD /6
FSAVE
m94/108byte
Store FPU state to
m94byte
or
m108byte
after checking for pending
unmasked floating-point exceptions. Then re-initialize the FPU.
DD /6
FNSAVE
m94/108byte
Store FPU environment to
m94byte
or
m108byte
without checking
for pending unmasked floating-point exceptions. Then re-initialize
the FPU.
Содержание ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
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Страница 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 12: ...1 1 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part I Application Architecture Guide ...
Страница 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Страница 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Страница 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Страница 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
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Страница 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 249: ...2 1 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part I System Architecture Guide ...
Страница 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Страница 380: ...2 132 Volume 2 Part 1 Interruptions ...
Страница 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Страница 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Страница 749: ...2 501 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part II System Programmer s Guide ...
Страница 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Страница 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Страница 808: ...2 560 Volume 2 Part 2 Context Management ...
Страница 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Страница 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Страница 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Страница 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
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Страница 941: ...3 42 Volume 3 Instruction Reference cmp illegal_operation_fault PR p1 0 PR p2 0 Interruptions Illegal Operation fault ...
Страница 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Страница 1191: ...3 292 Volume 3 Pseudo Code Functions Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Страница 1296: ......
Страница 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Страница 1564: ...4 262 Volume 4 Base IA 32 Instruction Reference LES Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1565: ...Volume 4 Base IA 32 Instruction Reference 4 263 LFS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1568: ...4 266 Volume 4 Base IA 32 Instruction Reference LGS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1583: ...Volume 4 Base IA 32 Instruction Reference 4 281 LSS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Страница 1663: ...Volume 4 Base IA 32 Instruction Reference 4 361 SHL SHR Shift Instructions See entry for SAL SAR SHL SHR ...
Страница 1668: ...4 366 Volume 4 Base IA 32 Instruction Reference SIDT Store Interrupt Descriptor Table Register See entry for SGDT SIDT ...
Страница 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Страница 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Страница 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...