17.41 LDRSB (register)

Load Register Signed Byte (register).

Syntax

LDRSB Wt, [Xn|SP, (Wm|Xm), extend {amount}] ; 32-bit with extended register offset general registers

LDRSB Wt, [Xn|SP, Xm{, LSL amount}] ; 32-bit with shifted register offset general registers

LDRSB Xt, [Xn|SP, (Wm|Xm), extend {amount}] ; 64-bit with extended register offset general registers

LDRSB Xt, [Xn|SP, Xm{, LSL amount}] ; 64-bit with shifted register offset general registers

Where:

Wt
Is the 32-bit name of the general-purpose register to be transferred.
Xn|SP
Is the 64-bit name of the general-purpose base register or stack pointer.
Wm
When "option<0>" is set to 0, is the 32-bit name of the general-purpose index register.
Xm
When "option<0>" is set to 1, is the 64-bit name of the general-purpose index register.
extend

Is the index extend specifier:

Can be one of UXTW, SXTW or SXTX.

amount
Is the index shift amount, it must be.
Xt
Is the 64-bit name of the general-purpose register to be transferred.

Usage

Load Register Signed Byte (register) calculates an address from a base register value and an offset register value, loads a byte from memory, sign-extends it, and writes it to a register. For information about memory accesses, see Load/Store addressing modes in the Arm® Architecture Reference Manual Arm®v8, for Arm®v8‑A architecture profile.

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