Arm® A64 Instruction Set Architecture: Future Architecture Technologies in the A architecture profile

CADD

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. 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.

if !HaveSVE2() then UNDEFINED;
integer esize = 8 << UInt(size);
integer m = UInt(Zm);
integer dn = UInt(Zdn);
boolean sub_i = (rot == '0');
boolean sub_r = (rot == '1');

Assembler Symbols

CheckSVEEnabled();
integer pairs = VL DIV (2 * esize);
bits(VL) operand1 = Z[dn];
bits(VL) operand2 = Z[m];
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]);
    integer elt2_r = SInt(Elem[operand2, 2 * p + 0, esize]);
    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] = acc_r<esize-1:0>;
    Elem[result, 2 * p + 1, esize] = acc_i<esize-1:0>;

Z[dn] = result;

Operational information

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.

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

• The MOVPRFX instruction must be unpredicated.
• The MOVPRFX instruction must specify the same destination register as this instruction.
• The destination register must not refer to architectural register state referenced by any other source operand register of this instruction.