Datasheet

165
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
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.
12.6.8.2 SXT and UXT
Sign extend and Zero extend.
Syntax
op{cond} {Rd,} Rm {, ROR #n}
op{cond} {Rd}, Rm {, ROR #n}
where:
op is 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.
cond is an optional condition code, see “Conditional Execution” .
Rd is the destination register.
Rm is the register holding the value to extend.
ROR #n is 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
These instructions do not affect the flags.
Examples