SQCADD

Saturating complex integer add with rotate

Add the real and imaginary components of the integral complex numbers from the first source vector to the complex numbers from the second source vector which have first been rotated by 90 or 270 degrees in the direction from the positive real axis towards the positive imaginary axis, when considered in polar representation, equivalent to multiplying the complex numbers in the second source vector by ±j beforehand. Destructively place the results in the corresponding elements of the first source vector. Each result element is saturated to the N-bit element's signed integer range -2(N-1) to (2(N-1))-1. This instruction is unpredicated.

Each complex number is represented in a vector register as an even/odd pair of elements with the real part in the even-numbered element and the imaginary part in the odd-numbered element.

Encoding: SVE2

Variants: FEAT_SVE2 || FEAT_SME (FEAT_SVE2 || FEAT_SME)

313029282726252423222120191817161514131211109876543210
0100010100000111011
sizeoprotZmZdn

SQCADD <Zdn>.<T>, <Zdn>.<T>, <Zm>.<T>, <const>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer m = UInt(Zm);
constant integer dn = UInt(Zdn);
constant boolean sub_i = (rot == '0');
constant boolean sub_r = (rot == '1');

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer pairs = VL DIV (2 * esize);
constant bits(VL) operand1 = Z[dn, VL];
constant bits(VL) operand2 = Z[m, VL];
bits(VL) result;

for p = 0 to pairs-1
    integer acc_r  = SInt(Elem[operand1, 2 * p + 0, esize]);
    integer acc_i  = SInt(Elem[operand1, 2 * p + 1, esize]);
    constant integer elt2_r = SInt(Elem[operand2, 2 * p + 0, esize]);
    constant integer elt2_i = SInt(Elem[operand2, 2 * p + 1, esize]);
    if sub_i then
        acc_r = acc_r - elt2_i;
        acc_i = acc_i + elt2_r;
    if sub_r then
        acc_r = acc_r + elt2_i;
        acc_i = acc_i - elt2_r;

    Elem[result, 2 * p + 0, esize] = SignedSat(acc_r, esize);
    Elem[result, 2 * p + 1, esize] = SignedSat(acc_i, esize);

Z[dn, VL] = result;

Explanations

<Zdn>: Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.
<T>: <Zm>: Is the name of the second source scalable vector register, encoded in the "Zm" field.
<const>:

Operational Notes

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is CONSTRAINED UNPREDICTABLE: