Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD Hoja De Datos

 98

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

Load register from memory.

Syntax

LDR{type}{cond} Rt, label

LDRD{cond} Rt, Rt2, label         ; Load two words

where:

type

is one of:

B

unsigned byte, zero extend to 32 bits.

SB

signed byte, sign extend to 32 bits.

H

unsigned halfword, zero extend to 32 bits.

SH

signed halfword, sign extend to 32 bits.

-

omit, for word.

cond

Rt

is the register to load or store.

Rt2

is the second register to load or store.

label

.

Operation

LDR loads a register with a value from a PC-relative memory address. The memory address is specified by a label or by
an offset from the PC.

The value to load or store can be a byte, halfword, or word. For load instructions, bytes and halfwords can either be
signed or unsigned. See 

label must be within a limited range of the current instruction. The table below shows the possible offsets between label
and the PC.

.

Restrictions

In these instructions:



Rt can be SP or PC only for word loads



Rt2 must not be SP and must not be PC



Rt must be different from Rt2.

Word, halfword, signed halfword, byte, signed byte

-4095 to 4095

Two words

-1020 to 1020