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

 113

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

Reverse bytes and Reverse bits.

Syntax

op{cond} Rd, Rn

where:

op

is any of:

REV Reverse byte order in a word.

REV16 Reverse byte order in each halfword independently.

REVSH Reverse byte order in the bottom halfword, and sign extend to 32 bits.

RBIT Reverse the bit order in a 32-bit word.

cond

Rd

is the destination register.

Rn

is the register holding the operand.

Operation

Use these instructions to change endianness of data:

REV converts either:



32-bit big-endian data into little-endian data



32-bit little-endian data into big-endian data.

REV16 converts either:



16-bit big-endian data into little-endian data



16-bit little-endian data into big-endian data.

REVSH converts either:



16-bit signed big-endian data into 32-bit signed little-endian data



16-bit signed little-endian data into 32-bit signed big-endian data.

Restrictions

Do not use SP and do not use PC

Condition Flags

These instructions do not change the flags.

Examples

REV   R3, R7; Reverse byte order of value in R7 and write it to R3

REV16 R0, R0; Reverse byte order of each 16-bit halfword in R0

REVSH R0, R5; Reverse Signed Halfword

REVHS R3, R7; Reverse with Higher or Same condition

RBIT  R7, R8; Reverse bit order of value in R8 and write the result to R7.