Volume 3: Instruction Reference
3:131
frsqrta
frsqrta — Floating-point Reciprocal Square Root Approximation
Format:
(
qp
) frsqrta.
sf f
1
,
p
2
=
f
3
Description:
If PR
qp
is 0, PR
p
2
is cleared and FR
f
1
remains unchanged.
If PR
qp
is 1, the following will occur:
• FR
f
1
is either set to an approximation (with a relative error < 2
-8.831
) of the
reciprocal square root of FR
f
3
, or set to the IEEE-754 mandated square root of FR
f
3
— if FR
f
3
is in the set {-Infinity, -Finite, -0, Pseudo-zero, +0, +Infinity, NaN,
Unsupported}.
• If FR
f
1
is set to an approximation of the reciprocal square root of FR
f
3
, then PR
p
2
is
set to 1; otherwise, it is set to 0.
• If FR
f
3
is such the approximation of its reciprocal square root may cause the
Newton-Raphson iterations to fail to produce the correct IEEE-754 square root
result, then a Floating-point Exception fault for Software Assist occurs.
System software is expected to compute the IEEE-754 square root, return the
result in FR
f
1
, and set PR
p
2
to 0.
• If FR
f
3
is a NaTVal, FR
f
1
is set to NaTVal instead of the computed result, and PR
p
2
is cleared.
The mnemonic values for
sf
are given in
.
Operation:
if (PR[
qp
]) {
fp_check_target_register(
f
1
);
if (tmp_isrcode = fp_reg_disabled(
f
1
,
f
3
, 0, 0))
disabled_fp_register_fault(tmp_isrcode, 0);
if (fp_is_natval(FR[
f
3
])) {
FR[
f
1
] = NATVAL;
PR[
p
2
] = 0;
} else {
tmp_default_result = frsqrta_exception_fault_check(
f
3
,
sf
,
&tmp_fp_env);
if (fp_raise_fault(tmp_fp_env))
fp_exception_fault(fp_decode_fault(tmp_fp_env));
if (fp_is_nan(tmp_default_result)) {
FR[
f
1
] = tmp_default_result;
PR[
p
2
] = 0;
} else {
tmp_fr3 = fp_normalize(fp_reg_read(FR[
f
3
]));
if (fp_is_zero(tmp_fr3)) {
FR[
f
1
] = tmp_fr3;
PR[
p
2
] = 0;
} else if (fp_is_pos_inf(tmp_fr3)) {
FR[
f
1
] = tmp_fr3;
PR[
p
2
] = 0;
} else {
FR[
f
1
] = fp_ieee_recip_sqrt(tmp_fr3);
PR[
p
2
] = 1;
}
}
fp_update_fpsr(
sf
, tmp_fp_env);
}
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 ...