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<!---======================= begin_copyright_notice ============================
Copyright (C) 2020-2022 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ==========================-->
## Opcode
RSQTM = 0x9c
## Format
| | | | | | |
| --- | --- | --- | --- | --- | --- |
| 0x9c(RSQTM) | Exec_size | Pred | Dst | PredDst | Src0 |
## Semantics
```
for (i = 0; i < exec_size; ++i){
if (ChEn[i]) {
dst[i] = rsqtm(src0[i])
preddst[i] = (rsqtm(src0[i]) == NAN/INF/ZERO)
}
}
```
## Description
```
Use rsqtm math macro to computes component-wise reciprocal square root of src0 and stores the results in <dst> and set <preddst>
to EO (early out) of rsqtm. If a bit in <preddst> is set, its corresponding <dst> is a special number (NAN/INF/ZERO); otherwise
<dst> is an initial approximation of the reciprocal sqaure root, and the further refinement on the apporoximation is needed to get
a result of expected precision.
```
- **Exec_size(ub):** Execution size
- Bit[2..0]: size of the region for source and destination operands
- 0b000: 1 element (scalar)
- 0b001: 2 elements
- 0b010: 4 elements
- 0b011: 8 elements
- 0b100: 16 elements
- 0b101: 32 elements
- Bit[7..4]: execution mask (explicit control over the enabled channels)
- 0b0000: M1
- 0b0001: M2
- 0b0010: M3
- 0b0011: M4
- 0b0100: M5
- 0b0101: M6
- 0b0110: M7
- 0b0111: M8
- 0b1000: M1_NM
- 0b1001: M2_NM
- 0b1010: M3_NM
- 0b1011: M4_NM
- 0b1100: M5_NM
- 0b1101: M6_NM
- 0b1110: M7_NM
- 0b1111: M8_NM
- **Pred(uw):** Predication control
- **Dst(vec_operand):** The destination operand. Operand class: general,indirect
- **PredDst(vec_operand):** The predicate destination operand. Operand class: predicate
- **Src0(vec_operand):** The first source operand. Operand class: general,indirect,immediate
#### Properties
- **Supported Types:** DF,F
- **Source Modifier:** arithmetic
## Text
```
[(<P>)] RSQTM (<exec_size>) <dst> <preddst> <src0>
```
## Notes
```
The instruction is intended to be used in a library function to provide different implementations of some math functions,
such as, a double reciprocal square root of precision 2ulp.
Saturation is not supported.
```
|
