You copied the Doc URL to your clipboard.

MSUB

Multiply-Subtract multiplies two register values, subtracts the product from a third register value, and writes the result to the destination register.

This instruction is used by the alias MNEG.

313029282726252423222120191817161514131211109876543210
sf0011011000Rm1RaRnRd
o0

32-bit (sf == 0)

MSUB <Wd>, <Wn>, <Wm>, <Wa>

64-bit (sf == 1)

MSUB <Xd>, <Xn>, <Xm>, <Xa>

integer d = UInt(Rd);
integer n = UInt(Rn);
integer m = UInt(Rm);
integer a = UInt(Ra);
integer destsize = if sf == '1' then 64 else 32;

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 holding the multiplicand, encoded in the "Rn" field.

<Wm>

Is the 32-bit name of the second general-purpose source register holding the multiplier, encoded in the "Rm" field.

<Wa>

Is the 32-bit name of the third general-purpose source register holding the minuend, encoded in the "Ra" 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 holding the multiplicand, encoded in the "Rn" field.

<Xm>

Is the 64-bit name of the second general-purpose source register holding the multiplier, encoded in the "Rm" field.

<Xa>

Is the 64-bit name of the third general-purpose source register holding the minuend, encoded in the "Ra" field.

Alias Conditions

AliasIs preferred when
MNEGRa == '11111'

Operation

bits(destsize) operand1 = X[n];
bits(destsize) operand2 = X[m];
bits(destsize) operand3 = X[a];

integer result;

result = UInt(operand3) - (UInt(operand1) * UInt(operand2));
X[d] = result<destsize-1:0>;

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.
Was this page helpful? Yes No