Index

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.

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 0 0 1 1 0 1 1 0 0 0 Rm 1 Ra Rn Rd
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);
constant integer destsize = 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 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

Alias Is preferred when
MNEG Ra == '11111'

Operation

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

integer result;

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

Operational information

If PSTATE.DIT is 1: