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INDEX (immediate, scalar)

Create index starting from immediate and incremented by general-purpose register.

Populates the destination vector by setting the first element to the first signed immediate integer operand and monotonically incrementing the value by the second signed scalar integer operand for each subsequent element. The scalar source operand is a general-purpose register in which only the least significant bits corresponding to the vector element size are used and any remaining bits are ignored. This instruction is unpredicated.

313029282726252423222120191817161514131211109876543210
00000100size1Rm010010imm5Zd

SVE

INDEX <Zd>.<T>, #<imm>, <R><m>

if !HaveSVE() then UNDEFINED;
integer esize = 8 << UInt(size);
integer m = UInt(Rm);
integer d = UInt(Zd);
integer imm = SInt(imm5);

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<T> Is the size specifier, encoded in size:
size <T>
00 B
01 H
10 S
11 D
<imm>

Is the signed immediate operand, in the range -16 to 15, encoded in the "imm5" field.

<R> Is a width specifier, encoded in size:
size <R>
01 W
x0 W
11 X
<m>

Is the number [0-30] of the source general-purpose register or the name ZR (31), encoded in the "Rm" field.

Operation

CheckSVEEnabled();
integer elements = VL DIV esize;
bits(esize) operand2 = X[m];
integer element2 = SInt(operand2);
bits(VL) result;

for e = 0 to elements-1
    integer index = imm + e * element2;
    Elem[result, e, esize] = index<esize-1:0>;

Z[d] = result;
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