UM10462
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User manual
Rev. 5.5 — 21 December 2016
475 of 523
NXP Semiconductors
UM10462
Chapter 24: LPC11U3x/2x/1x Appendix ARM Cortex-M0
24.4.5.7.4
Condition flags
These instructions do not change the flags.
24.4.5.7.5
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
24.4.5.8 SXT and UXT
Sign extend and Zero extend.
24.4.5.8.1
Syntax
SXTB Rd,
Rm
SXTH Rd,
Rm
UXTB Rd,
Rm
UXTH Rd,
Rm
where:
Rd
is the destination register.
Rm
is the register holding the value to be extended.
24.4.5.8.2
Operation
These instructions 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.
24.4.5.8.3
Restrictions
In these instructions,
Rd
and
Rm
must only specify R0-R7.
24.4.5.8.4
Condition flags
These instructions do not affect the flags.
24.4.5.8.5
Examples
SXTH R4, R6
; Obtain the lower halfword of the
; value in R6 and then sign extend to
; 32 bits and write the result to R4.
UXTB R3, R1
; Extract lowest byte of the value in R10 and zero
; extend it, and write the result to R3
24.4.5.9 TST
Test bits.