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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SMUSD, SMUSDX

Signed Multiply Subtract Dual performs two signed 16 x 16-bit multiplications. It subtracts one of the products from the other, and writes the result to the destination register.

Optionally, the instruction can exchange the halfwords of the second operand before performing the arithmetic. This produces top x bottom and bottom x top multiplication.

Overflow cannot occur.

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

A1

Decode for all variants of this encoding

let d : integer = UInt(Rd); let n : integer = UInt(Rn); let m : integer = UInt(Rm); let m_swap : boolean = (M == '1'); if d == 15 || n == 15 || m == 15 then UnpredictableProcedure(); end;

T1

Decode for all variants of this encoding

let d : integer = UInt(Rd); let n : integer = UInt(Rn); let m : integer = UInt(Rm); let m_swap : boolean = (M == '1'); // Armv8-A removes UNPREDICTABLE for R13 if d == 15 || n == 15 || m == 15 then UnpredictableProcedure(); end;

Assembler Symbols