Arm VERSION 1.2 Manual do Utilizador descarregar pdf (Página 192)

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101

ARM Instruction Reference

4.9.3 LDR ARM pseudo-instruction

Load a register with either:

• a 32-bit constant value

• an address.

Note

This section describes the

LDR

pseudo-instruction only. See ARM memory access

instructions on page 4-6 for information on the

LDR

instruction.

Syntax

LDR{cond} register,=[expr | label-expr]

where:

cond

is an optional condition code.

is the register to be loaded.

expr

evaluates to a numeric constant:

• the assembler generates a

MOV

MVN

instruction, if the value of

expr

is within range

• if the value of

expr

is not within range of a

MOV

MVN

instruction,

the assembler places the constant in a literal pool and generates a

program-relative

LDR

instruction that reads the constant from the

literal pool.

label-expr

is a program-relative or external expression. The assembler places the

value of

label-expr

in a literal pool and generates a program-relative

LDR

instruction that loads the value from the literal pool.

label-expr

is an external expression, or is not contained in the current

section, the assembler places a linker relocation directive in the object

file. The linker generates the address at link time.

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