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1:86
Volume 1, Part 1: Floating-point Programming Model
Real numbers reside in 82-bit floating-point registers in a three-field binary format (see
). The three fields are:
• The 64-bit
significand
field, b
63
.
b
62
b
61 ..
b
1
b
0,
contains the number's significant
digits. This field is composed of an explicit integer bit (significand{63}), and 63 bits
of fraction (significand{62:0}).
• The 17-bit
exponent
field locates the binary point within or beyond the significant
digits (i.e., it determines the number's magnitude). The exponent field is biased by
65535 (0xFFFF). An exponent field of all ones is used to encode the special values
for IEEE signed infinity and NaNs. An exponent field of all zeros and a significand
field of all zeros is used to encode the special values for IEEE signed zeros. An
exponent field of all zeros and a non-zero significand field encodes the
double-extended real denormals and double-extended real pseudo-denormals.
• The 1-bit
sign
field indicates whether the number is positive (sign=0) or negative
(sign=1).
The value of a finite floating-point number, encoded with non-zero exponent field, can
be calculated using the expression:
The value of a finite floating-point number, encoded with zero exponent field, can be
calculated using the expression:
Integers (64-bit signed/unsigned) and Parallel FP numbers reside in the 64-bit
significand field. In their canonical form, the exponent field is set to 0x1003E (biased
63) and the sign field is set to 0.
5.1.3
Representation of Values in Floating-point Registers
The floating-point register encodings are grouped into classes and subclasses and listed
below in
(shaded encodings are unsupported). The last two table entries
contain the values of the constant floating-point registers, FR 0 and FR 1. The constant
value in FR 1 does not change for the parallel single precision instructions or for the
integer multiply accumulate instruction.
Figure 5-1.
Floating-point Register Format
81
80
64 63
0
sign
exponent
significand (with explicit integer bit)
1
17
64
(-1)
(sign)
* 2
(exponent - 65535)
* (significand{63}.significand{62:0}
2
)
(-1)
(sign)
* 2
(-16382)
* (significand{63}.significand{62:0}
2
)
Table 5-2.
Floating-point Register Encodings
Class or Subclass
Sign
(1 bit)
Biased
Exponent
(17-bits)
Significand
i.bb...bb
(Explicit Integer Bit is Shown)
(64-bits)
NaNs
0/1
0x1FFFF
1.000...01 through 1.111...11
Quiet NaNs
0/1
0x1FFFF
1.100...00 through 1.111...11
Quiet NaN Indefinite
a
1
0x1FFFF
1.100...00
Signaling NaNs
0/1
0x1FFFF
1.000...01 through 1.011...11
Infinity
0/1
0x1FFFF
1.000...00
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 ...