ADCS

Add with carry, setting flags

This instruction adds two register values and the Carry flag 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
	0	1	1	1	0	1	0	0	0	0						0	0	0	0	0	0
sf	op	S									Rm											Rn					Rd

32-bit (sf == 0)

ADCS <Wd>, <Wn>, <Wm>

64-bit (sf == 1)

ADCS <Xd>, <Xn>, <Xm>

Decoding algorithm

constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
constant integer datasize = 32 << UInt(sf);

Operation

constant bits(datasize) operand1 = X[n, datasize];
constant bits(datasize) operand2 = X[m, datasize];
bits(datasize) result;
bits(4) nzcv;

(result, nzcv) = AddWithCarry(operand1, operand2, PSTATE.C);

X[d, datasize] = result;
PSTATE. = nzcv;

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 first general-purpose source register, encoded in the "Rn" field.
<Wm>: Is the 32-bit name of the second general-purpose source register, encoded in the "Rm" field.
<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 first general-purpose source register, encoded in the "Rn" field.
<Xm>: Is the 64-bit name of the second general-purpose source register, encoded in the "Rm" 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.