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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UMULH

Unsigned multiply high

This instruction multiplies two 64-bit register values, and writes bits[127:64] of the 128-bit result to the 64-bit destination register.

Decode for this encoding

let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm);