This is a collection of Intel®’ IA32® Software Developer's Manuals (URL of the day) and AMD' AMD64 Architecture Programmer's Manual together with the related specifications, application notes, white papers, and change logs. The collection aims to keep all available revisions. It was originally created by Michal Necasek, see OS/2 Museum.

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UMAAL

Unsigned Multiply Accumulate Accumulate Long multiplies two unsigned 32-bit values to produce a 64-bit value, adds two unsigned 32-bit values, and writes the 64-bit result to two registers.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1

Decode for this encoding

let dLo : integer = UInt(RdLo); let dHi : integer = UInt(RdHi); let n : integer = UInt(Rn); let m : integer = UInt(Rm); if dLo == 15 || dHi == 15 || n == 15 || m == 15 then UnpredictableProcedure(); end; if dHi == dLo then UnpredictableProcedure(); end;

CONSTRAINED UNPREDICTABLE behavior

If dHi == dLo, then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as NOP.
• The value in the destination register is unknown.

T1

Decode for this encoding

let dLo : integer = UInt(RdLo); let dHi : integer = UInt(RdHi); let n : integer = UInt(Rn); let m : integer = UInt(Rm); if dLo == 15 || dHi == 15 || n == 15 || m == 15 then UnpredictableProcedure(); end; // Armv8-A removes UNPREDICTABLE for R13 if dHi == dLo then UnpredictableProcedure(); end;

CONSTRAINED UNPREDICTABLE behavior

If dHi == dLo, then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as NOP.
• The value in the destination register is unknown.

Assembler Symbols