Index

SBCS

Subtract with Carry, setting flags, subtracts a register value and the value of NOT (Carry flag) from a register value, and writes the result to the destination register. It updates the condition flags based on the result.

This instruction is used by the alias NGCS.

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
sf 1 1 1 1 0 1 0 0 0 0 Rm 0 0 0 0 0 0 Rn Rd
op S

32-bit (sf == 0)

SBCS <Wd>, <Wn>, <Wm>

64-bit (sf == 1)

SBCS <Xd>, <Xn>, <Xm>

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

Assembler Symbols

<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.

Alias Conditions

Alias Is preferred when
NGCS Rn == '11111'

Operation

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

operand2 = NOT(operand2);

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

PSTATE.<N,Z,C,V> = nzcv;

X[d, datasize] = result;

Operational information

If PSTATE.DIT is 1: