Cortex-M3 Processor (Reference Material)
UG0331 User Guide Revision 15.0 82
3.6.8.3.2 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.
3.6.8.3.3 Restrictions
Do not use SP and do not use PC.
3.6.8.3.4 Condition Flags
These instructions do not affect the flags.
Examples
SXTH R4, R6, ROR #16 ; Rotate R6 right by 16 bits, then obtain the lower
; halfword of the result and then sign extend to
; 32 bits and write the result to R4.
UXTB R3, R10 ; Extract lowest byte of the value in R10 and zero
; extend it, and write the result to R3.
3.6.9 Branch and Control Instructions
The following table lists the branch and control instructions:
3.6.9.1 B, BL, BX, and BLX
Branch instructions.
3.6.9.1.1 Syntax
B{cond} label
BL{cond} label
BX{cond} Rm
BLX{cond} Rm
where:
B is branch (immediate).
Table 36 • Branch and Control Instructions
Mnemonic Brief description See
B Branch B, BL, BX, and BLX, page 83
BL Branch with Link B, BL, BX, and BLX, page 83
BLX Branch indirect with Link B, BL, BX, and BLX, page 83
BX Branch indirect B, BL, BX, and BLX, page 83
CBNZ Compare and Branch if Non Zero CBZ and CBNZ, page 85
CBZ Compare and Branch if Zero CBZ and CBNZ, page 85
IT If-Then IT, page 85
TBB Table Branch Byte TBB and TBH, page 87
TBH Table Branch Halfword TBB and TBH, page 87
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