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Volume 4: Base IA-32 Instruction Reference
4:115
FCOMI/FCOMIP/
FUCOMI/FUCOMIP—Compare Real and Set EFLAGS
Description
Compares the contents of register ST(0) and ST(
i
) and sets the status flags ZF, PF, and
CF in the EFLAGS register according to the results (see the table below). The sign of
zero is ignored for comparisons, so that -0.0 = +0.0.
The FCOMI/FCOMIP instructions perform the same operation as the FUCOMI/FUCOMIP
instructions. The only difference is how they handle QNaN operands. The
FCOMI/FCOMIP instructions set the status flags to “unordered” and generate an
invalid-arithmetic-operand exception (#IA) when either or both of the operands is a
NaN value (SNaN or QNaN) or is in an unsupported format.
The FUCOMI/FUCOMIP instructions perform the same operation as the FCOMI/FCOMIP
instructions, except that they do not generate an invalid-arithmetic-operand exception
for QNaNs.
If invalid-operation exception is unmasked, the status flags are not set if the
invalid-arithmetic-operand exception is generated.
The FCOMIP and FUCOMIP instructions also pop the register stack following the
comparison operation. To pop the register stack, the processor marks the ST(0) register
as empty and increments the stack pointer (TOP) by 1.
Opcode
Instruction
Description
DB F0+i
FCOMI ST, ST(
i
)
Compare ST(0) with ST(
i
) and set status flags accordingly
DF F0+i
FCOMIP ST, ST(
i
)
Compare ST(0) with ST(
i
), set status flags accordingly, and pop
register stack
DB E8+i
FUCOMI ST, ST(
i
)
Compare ST(0) with ST(
i
), check for ordered values, and set
status flags accordingly
DF E8+i
FUCOMIP ST, ST(
i
)
Compare ST(0) with ST(
i
), check for ordered values, set status
flags accordingly, and pop register stack
Comparison Results
ZF
PF
CF
ST0 > ST(
i
)
0
0
0
ST0 < ST(
i
)
0
0
1
ST0 = ST(
i
)
1
0
0
Unordered
a
a. Flags not set if unmasked invalid-arithmetic- operand
(#IA) exception is generated.
1
1
1
Содержание ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Страница 1: ......
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 ...
Страница 230: ......
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 ...
Страница 891: ......
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 ...