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Volume 1, Part 1: Floating-point Programming Model
All register encodings are allowed as inputs to arithmetic operations. The result of an
arithmetic operation is always the most normalized register format representation of
the computed value, with the exponent range limited from Emin to Emax of the
destination type, and the significand precision limited to the number of precision bits of
the destination type. Computed values, such as zeros, infinities, and NaNs that are
outside these bounds are represented by the corresponding unique register format
encoding. Double-extended real denormal results are mapped to the register format
exponent of 0x00000 (instead of 0x0C001). Unsupported encodings (Pseudo-NaNs and
Pseudo-Infinities), Pseudo-zeros and Double-extended Real Pseudo-denormals are
never produced as a result of an arithmetic operation.
Arithmetic on pseudo-zeros operates exactly as an equivalently signed zero, with one
exception. Pseudo-zero multiplied by infinity returns the correctly signed infinity instead
of an Invalid Operation Floating-Point Exception fault (and QNaN). Also, pseudo-zeros
are classified as unnormalized numbers, not zeros.
5.2
Floating-point Status Register
The Floating-Point Status Register (FPSR) contains the dynamic control and status
information for floating-point operations. There is one main set of control and status
information (FPSR.sf0), and three alternate sets (FPSR.sf1, FPSR.sf2, FPSR.sf3). The
FPSR layout is shown in
and its fields are defined in
gives the FPSR’s status field description and
shows their layout.
IA-32 Stack Double Real Denormals
(produced when computation model is
IA-32 Stack Double)
0/1
0x00000
0.000...01...(11)0s
through
0.111...11...(11)0s
Double-Extended Real Pseudo-Denormals
(IA-32 stack and memory format)
0/1
0x00000
1.000...00 through 1.111...11
Pseudo-Zeros
0/1
0x00001
through
0x1FFFD
0.000...00
1
0x1FFFE
0.000...00
NaTVal
c
0
0x1FFFE
0.000...00
Zero
0/1
0x00000
0.000...00
FR 0 (positive zero)
0
0x00000
0.000...00
FR 1 (positive one)
0
0x0FFFF
1.000...00
a. Created by a masked real invalid operation.
b. Created by a masked integer invalid operation.
c. Created by an unsuccessful speculative memory operation.
Figure 5-2.
Floating-point Status Register Format
63
58 57
45 44
32 31
19 18
6
5
0
rv
sf3
sf2
sf1
sf0
traps
6
13
13
13
13
6
Table 5-2.
Floating-point Register Encodings (Continued)
Class or Subclass
Sign
(1 bit)
Biased
Exponent
(17-bits)
Significand
i.bb...bb
(Explicit Integer Bit is Shown)
(64-bits)
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 ...