Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

172

Examples

PKHBT

R3, R4, R5 LSL #0  ; Writes bottom halfword of R4 to bottom halfword of

 ; R3, writes top halfword of R5, unshifted, to top 

 ; halfword of R3

PKHTB   R4, R0, R2 ASR #1  ; Writes R2 shifted right by 1 bit to bottom halfword

; of R4, and writes top halfword of R0 to top

 ; halfword of R4.

Sign extend and Zero extend.
Syntax

op{cond} {Rd,} Rm {, ROR #n}

op{cond} {Rd}, Rm {, ROR #n}

where:
opis one of:
SXTB Sign extends an 8-bit value to a 32-bit value.
SXTH Sign extends a 16-bit value to a 32-bit value.
SXTB16 Sign extends two 8-bit values to two 16-bit values.
UXTB Zero extends an 8-bit value to a 32-bit value.
UXTH Zero extends a 16-bit value to a 32-bit value.
UXTB16 Zero extends two 8-bit values to two 16-bit values.
condis an optional condition code, see 

.

Rdis the destination register.
Rmis the register holding the value to extend.
ROR #nis one of:
ROR #8 Value from Rm is rotated right 8 bits.
Operation
These instructions do the following:

1. Rotate the value from Rm right by 0, 8, 16 or 24 bits.

2. Extract bits from the resulting value:

̶

SXTB extracts bits[7:0] and sign extends to 32 bits.

̶

UXTB extracts bits[7:0] and zero extends to 32 bits.

̶

SXTH extracts bits[15:0] and sign extends to 32 bits.

̶

UXTH extracts bits[15:0] and zero extends to 32 bits.

̶

SXTB16 extracts bits[7:0] and sign extends to 16 bits,

and extracts bits [23:16] and sign extends to 16 bits.

̶

UXTB16 extracts bits[7:0] and zero extends to 16 bits,

and extracts bits [23:16] and zero extends to 16 bits.

Restrictions
Do not use SP and do not use PC.
Condition Flags