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SQRDMULH (by element)

Signed saturating Rounding Doubling Multiply returning High half (by element). This instruction multiplies each vector element in the first source SIMD&FP register by the specified vector element of the second source SIMD&FP register, doubles the results, places the most significant half of the final results into a vector, and writes the vector to the destination SIMD&FP register.

The results are rounded. For truncated results, see SQDMULH.

If any of the results overflows, they are saturated. If saturation occurs, the cumulative saturation bit FPSR.QC is set.

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 2 classes: Scalar and Vector

Scalar

313029282726252423222120191817161514131211109876543210
01011111sizeLMRm1101H0RnRd
op

Scalar

SQRDMULH <V><d>, <V><n>, <Vm>.<Ts>[<index>]

integer idxdsize = if H == '1' then 128 else 64; integer index; bit Rmhi; case size of when '01' index = UInt(H:L:M); Rmhi = '0'; when '10' index = UInt(H:L); Rmhi = M; otherwise UnallocatedEncoding(); integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rmhi:Rm); integer esize = 8 << UInt(size); integer datasize = esize; integer elements = 1; boolean round = (op == '1');

Vector

313029282726252423222120191817161514131211109876543210
0Q001111sizeLMRm1101H0RnRd
op

Vector

SQRDMULH <Vd>.<T>, <Vn>.<T>, <Vm>.<Ts>[<index>]

integer idxdsize = if H == '1' then 128 else 64; integer index; bit Rmhi; case size of when '01' index = UInt(H:L:M); Rmhi = '0'; when '10' index = UInt(H:L); Rmhi = M; otherwise UnallocatedEncoding(); integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rmhi:Rm); integer esize = 8 << UInt(size); integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize; boolean round = (op == '1');

Assembler Symbols

<V> Is a width specifier, encoded in size:
size<V>
00RESERVED
01H
10S
11RESERVED
Is a width specifier, encoded in size:
size<V>
00RESERVED
01H
10S
11RESERVED
<d>

Is the number of the SIMD&FP destination register, encoded in the "Rd" field.

<n>

Is the number of the first SIMD&FP source register, encoded in the "Rn" field.

<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<T> Is an arrangement specifier, encoded in size:Q:
sizeQ<T>
00xRESERVED
0104H
0118H
1002S
1014S
11xRESERVED
Is an arrangement specifier, encoded in size:Q:
sizeQ<T>
00xRESERVED
0104H
0118H
1002S
1014S
11xRESERVED
<Vn>

Is the name of the first SIMD&FP source register, encoded in the "Rn" field.

<Vm> Is the name of the second SIMD&FP source register, encoded in size:M:Rm:
size<Vm>
00RESERVED
010:Rm
10M:Rm
11RESERVED
Restricted to V0-V15 when element size <Ts> is H.
Is the name of the second SIMD&FP source register, encoded in size:M:Rm:
size<Vm>
00RESERVED
010:Rm
10M:Rm
11RESERVED
Restricted to V0-V15 when element size <Ts> is H.
<Ts> Is an element size specifier, encoded in size:
size<Ts>
00RESERVED
01H
10S
11RESERVED
Is an element size specifier, encoded in size:
size<Ts>
00RESERVED
01H
10S
11RESERVED
<index> Is the element index, encoded in size:L:H:M:
size<index>
00RESERVED
01H:L:M
10H:L
11RESERVED
Is the element index, encoded in size:L:H:M:
size<index>
00RESERVED
01H:L:M
10H:L
11RESERVED

Operation

CheckFPAdvSIMDEnabled64(); bits(datasize) operand1 = V[n]; bits(idxdsize) operand2 = V[m]; bits(datasize) result; integer round_const = if round then 1 << (esize - 1) else 0; integer element1; integer element2; integer product; boolean sat; element2 = SInt(Elem[operand2, index, esize]); for e = 0 to elements-1 element1 = SInt(Elem[operand1, e, esize]); product = (2 * element1 * element2) + round_const; // The following only saturates if element1 and element2 equal -(2^(esize-1)) (Elem[result, e, esize], sat) = SignedSatQ(product >> esize, esize); if sat then FPSR.QC = '1'; V[d] = result;


Internal version only: isa v29.05v27.02, AdvSIMD v26.0, pseudocode v35.3v34.2.2 ; Build timestamp: 2018-06-16T092018-03-28T19:4555

Copyright © 2010-2018 ARM Limited or its affiliates. All rights reserved. This document is Non-Confidential.

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