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Samsung S3C2440A User Manual

Page 89

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ARM INSTRUCTION SET

S3C2440A RISC MICROPROCESSOR

3-32

ASSEMBLER SYNTAX

{cond}{B}{T} Rd,

where:

LDR

Load from memory into a register

STR

Store from a register into memory

{cond}

Two-character condition mnemonic. See Table 3-2.

{B}

If B is present then byte transfer, otherwise word transfer

{T}

If T is present the W bit will be set in a post-indexed instruction, forcing non-privileged

mode for the transfer cycle. T is not allowed when a pre-indexed addressing mode is

specified

or

implied.

Rd

An expression evaluating to a valid register number.

Rn and Rm

Expressions evaluating to a register number. If Rn is R15 then the assembler will
subtract 8 from the offset value to allow for ARM920T pipelining.
In this case base write-back should not be specified.

can be:

1

An expression which generates an address:

The assembler will attempt to generate an instruction using the PC as a base and a

corrected immediate offset to address the location given by evaluating the expression.

This will be a PC relative, pre-indexed address. If the address is out of range, an error
will be generated.

2

A pre-indexed addressing specification:

[Rn]

offset

of

zero

[Rn,<#expression>]{!}

offset

of

bytes

[Rn,{+/-}Rm{,}]{!}

offset of +/- contents of index register, shifted

by

3

A post-indexed addressing specification:

[Rn],<#expression>

offset of bytes

[Rn],{+/-}Rm{,}

offset of +/- contents of index register, shifted as

by .

General shift operation (see data processing instructions) but you cannot specify the shift

amount by a register.

{!}

Writes back the base register (set the W bit) if! is present.