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.

If you have a public document, related to the IA32® specifications and missing from the collection, please mail it to me. The content of this URL and all sub-ULRs is available for convenient bulk download by rsync x86docs password "" (empty).

LDTRSW -- A64

LDTRSW

Load register signed word (unprivileged)

This instruction loads a word from memory, sign-extends it to 64 bits, and writes the result to a register. The address that is used for the load is calculated from a base register and an immediate offset.

Explicit Memory effects produced by the instruction behave as if the instruction was executed at EL0 if the Effective value of PSTATE.UAO is 0 and either:

Otherwise, the Explicit Memory effects operate with the restrictions determined by the Exception level at which the instruction is executed.

For information about addressing modes, see Load/Store addressing modes.

313029282726252423222120191817161514131211109876543210
10111000100imm910RnRt
sizeVRopc

Encoding

LDTRSW <Xt>, [<Xn|SP>{, #<simm>}]

Decode for this encoding

let offset : bits(64) = SignExtend{}(imm9);

Assembler Symbols

<Xt>

Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.

<Xn|SP>

Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.

<simm>

Is the optional signed immediate byte offset, in the range -256 to 255, defaulting to 0 and encoded in the "imm9" field.

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.


2025-09_rel_asl1 2026-03-12 12:57:38

Copyright © 2010-2025 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.