1:88
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)
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 ...