Signed Multiply Long multiplies two 32-bit signed values to produce a 64-bit result.
In A32 instructions, the condition flags can optionally be updated based on the result. Use of this option adversely affects performance on many implementations.
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
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 |
!= 1111 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | S | RdHi | RdLo | Rm | 1 | 0 | 0 | 1 | Rn | |||||||||||||||
cond |
dLo = UInt(RdLo); dHi = UInt(RdHi); n = UInt(Rn); m = UInt(Rm); setflags = (S == '1'); if dLo == 15 || dHi == 15 || n == 15 || m == 15 then UNPREDICTABLE; if dHi == dLo then UNPREDICTABLE;
If dHi == dLo, then one of the following behaviors must occur:
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | Rn | RdLo | RdHi | 0 | 0 | 0 | 0 | Rm |
dLo = UInt(RdLo); dHi = UInt(RdHi); n = UInt(Rn); m = UInt(Rm); setflags = FALSE; if dLo == 15 || dHi == 15 || n == 15 || m == 15 then UNPREDICTABLE; // ARMv8-A removes UNPREDICTABLE for R13 if dHi == dLo then UNPREDICTABLE;
If dHi == dLo, then one of the following behaviors must occur:
For more information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors.
<c> |
<q> |
<RdLo> |
Is the general-purpose destination register for the lower 32 bits of the result, encoded in the "RdLo" field. |
<RdHi> |
Is the general-purpose destination register for the upper 32 bits of the result, encoded in the "RdHi" field. |
<Rn> |
Is the first general-purpose source register holding the multiplicand, encoded in the "Rn" field. |
<Rm> |
Is the second general-purpose source register holding the multiplier, encoded in the "Rm" field. |
if ConditionPassed() then EncodingSpecificOperations(); result = SInt(R[n]) * SInt(R[m]); R[dHi] = result<63:32>; R[dLo] = result<31:0>; if setflags then PSTATE.N = result<63>; PSTATE.Z = IsZeroBit(result<63:0>); // PSTATE.C, PSTATE.V unchanged
Internal version only: isa v00_79, pseudocode v34.2 ; Build timestamp: 2017-12-19T15:42
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