ANDS (immediate)

Bitwise AND (immediate), setting flags

This instruction performs a bitwise AND of a register value and an immediate value, and writes the result to the destination register. It updates the condition flags based on the result.

Encoding: Setting the condition flags

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
	1	1	1	0	0	1	0	0
sf	opc								N	immr						imms						Rn					Rd

32-bit (sf == 0 && N == 0)

ANDS <Wd>, <Wn>, #<imm>

64-bit (sf == 1)

ANDS <Xd>, <Xn>, #<imm>

Decoding algorithm

if sf == '0' && N != '0' then EndOfDecode(Decode_UNDEF);
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer datasize = 32 << UInt(sf);
bits(datasize) imm;
(imm, -) = DecodeBitMasks(N, imms, immr, TRUE, datasize);

Operation

constant bits(datasize) operand1 = X[n, datasize];
constant bits(datasize) operand2 = imm;

constant bits(datasize) result = operand1 AND operand2;

X[d, datasize] = result;
PSTATE. = result:IsZeroBit(result):'00';

Explanations

<Wd>: Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field.
<Wn>: Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field.
<imm>: For the "32-bit" variant: is the bitmask immediate, encoded in "imms:immr".
<imm>: For the "64-bit" variant: is the bitmask immediate, encoded in "N:imms:immr".
<Xd>: Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.
<Xn>: Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field.

Operational Notes

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.