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
Summary of Contents for ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Page 1: ......
Page 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Page 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Page 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Page 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Page 230: ......
Page 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Page 380: ...2 132 Volume 2 Part 1 Interruptions ...
Page 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Page 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Page 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Page 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Page 808: ...2 560 Volume 2 Part 2 Context Management ...
Page 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Page 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Page 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Page 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Page 891: ......
Page 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Page 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Page 1296: ......
Page 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...