Datasheet

169
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
12.6.9.1 BFC and BFI
Bit Field Clear and Bit Field Insert.
Syntax
BFC{cond} Rd, #lsb, #width
BFI{cond} Rd, Rn, #lsb, #width
where:
cond is an optional condition code, see “Conditional Execution” .
Rd is the destination register.
Rn is the source register.
lsb is the position of the least significant bit of the bitfield. lsb must be in the range
0 to 31.
width is the width of the bitfield and must be in the range 1 to 32-lsb.
Operation
BFC clears a bitfield in a register. It clears width bits in Rd, starting at the low bit position lsb. Other bits in Rd are
unchanged.
BFI copies a bitfield into one register from another register. It replaces width bits in Rd starting at the low bit position lsb,
with width bits from Rn starting at bit[0]. Other bits in Rd are unchanged.
Restrictions
Do not use SP and do not use PC.
Condition Flags
These instructions do not affect the flags.
Examples
BFC R4, #8, #12 ; Clear bit 8 to bit 19 (12 bits) of R4 to 0
BFI R9, R2, #8, #12 ; Replace bit 8 to bit 19 (12 bits) of R9 with
; bit 0 to bit 11 from R2.