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1:90
Volume 1, Part 1: Floating-point Programming Model
fields flags are merely indications of the occurrence of floating-point excep-
tions.
Flush-to-Zero (FTZ) mode causes results which encounter “tininess” (see
Tininess, Inexact and Underflow” on page 1:106
) to be truncated to the correctly
signed zero. Flush-to-Zero mode can be enabled only if Underflow is disabled. If
Underflow is enabled then it takes priority and Flush-to-Zero mode is ignored. Note that
the software exception handler could examine the Flush-to-Zero mode bit and choose
to emulate the Flush-to-Zero operation when an enabled Underflow exception arises.
The FPSR.sf
x
.u and FPSR.sf
x
.i bits will be set to 1 when a result is flushed to the
correctly signed zero because of Flush-to-Zero mode. If enabled, an inexact result
exception is signaled.
A floating-point result is rounded based on the instruction’s.
pc
completer and the status
field’s
wre
,
pc
, and
rc
control fields. The result’s significand precision and exponent
range are determined as described in
Table 5-6, “Floating-point Computation Model
Control Definitions” on page 1:90
. If the result isn’t exact, FPSR.sf
x
.
rc
specifies the
rounding direction (see
Table 5-5.
Floating-point Rounding Control Definitions
Nearest
(or even)
- Infinity
(down)
+ Infinity
(up)
Zero
(truncate/chop)
FPSR.sf
x
.rc
00
01
10
11
Table 5-6.
Floating-point Computation Model Control Definitions
Computation Model Control Fields
Computation Model Selected
Instruction’s
.pc
Completer
FPSR.sfx’s
Dynamic
pc
Field
FPSR.sfx’s
Dynamic
wre
Field
Significand
Precision
Exponent
Range
Computational Style
.s
ignored
0
24 bits
8 bits
IEEE real single
.d
ignored
0
53 bits
11 bits
IEEE real double
.s
ignored
1
24 bits
17 bits
Register format range,
single precision
.d
ignored
1
53 bits
17 bits
Register format range,
double precision
none
00
0
24 bits
15 bits
IA-32 stack single
none
01
0
N.A.
N.A.
Reserved
none
10
0
53 bits
15 bits
IA-32 stack double
none
11
0
64 bits
15 bits
IA-32 double-extended
none
00
1
24 bits
17 bits
Register format range,
single precision
none
01
1
N.A.
N.A.
Reserved
none
10
1
53 bits
17 bits
Register format range,
double precision
none
11
1
64 bits
17 bits
Register format range,
double-extended precision
not applicable
a
a. For parallel FP instructions which have no.
pc
completer (e.g., fpma).
ignored
ignored
24 bits
8 bits
A pair of IEEE real singles
not applicable
b
b. For non-parallel FP instructions which have no.
pc
completer (e.g., frcpa).
ignored
ignored
64 bits
17 bits
Register format range,
double-extended precision
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 ...