Floating-point Reciprocal Square Root Estimate. This instruction calculates an approximate square root for each vector element in the source SIMD&FP register, places the result in a vector, and writes the vector to the destination SIMD&FP register.
This instruction can generate a floating-point exception. Depending on the settings in FPCR, the exception results in either a flag being set in FPSR or a synchronous exception being generated. For more information, see Floating-point exception traps.
Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.
It has encodings from 4 classes: Scalar half precision , Scalar single-precision and double-precision , Vector half precision and Vector single-precision and double-precision
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | Rn | Rd | ||||||||
if !HaveFP16Ext() then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer esize = 16; integer datasize = esize; integer elements = 1;
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| 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | sz | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | Rn | Rd | ||||||||
integer d = UInt(Rd); integer n = UInt(Rn); integer esize = 32 << UInt(sz); integer datasize = esize; integer elements = 1;
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| 0 | Q | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | Rn | Rd | ||||||||
if !HaveFP16Ext() then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer esize = 16; integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize;
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| 0 | Q | 1 | 0 | 1 | 1 | 1 | 0 | 1 | sz | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | Rn | Rd | ||||||||
integer d = UInt(Rd); integer n = UInt(Rn); if sz:Q == '10' then UNDEFINED; integer esize = 32 << UInt(sz); integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize;
| <Hd> |
Is the 16-bit name of the SIMD&FP destination register, encoded in the "Rd" field. |
| <Hn> |
Is the 16-bit name of the SIMD&FP source register, encoded in the "Rn" field. |
| <V> |
Is a width specifier,
encoded in
sz:
|
| <d> |
Is the number of the SIMD&FP destination register, encoded in the "Rd" field. |
| <n> |
Is the number of the SIMD&FP source register, encoded in the "Rn" field. |
| <Vd> |
Is the name of the SIMD&FP destination register, encoded in the "Rd" field. |
| <Vn> |
Is the name of the SIMD&FP source register, encoded in the "Rn" field. |
CheckFPAdvSIMDEnabled64(); bits(datasize) operand = V[n]; bits(datasize) result; bits(esize) element; for e = 0 to elements-1 element = Elem[operand, e, esize]; Elem[result, e, esize] = FPRSqrtEstimate(element, FPCR); V[d] = result;
Internal version only: isa v32.13, AdvSIMD v29.04, pseudocode morello-2022-01_rc2, capabilities morello-2022-01_rc2 ; Build timestamp: 2022-01-11T11:23
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