ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Instruction Details
A8.6.18 BFI
Bit Field Insert copies any number of low order bits from a register into the same number of adjacent bits at
any position in the destination register.
Encoding T1 ARMv6T2, ARMv7
BFI ,,#,#
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 1 1 0 (0) 1 1 0 1 1 0 Rn 0 imm3 Rd imm2 (0) msb
if Rn == ‘1111’ then SEE BFC;
d = UInt(Rd); n = UInt(Rn); msbit = UInt(msb); lsbit = UInt(imm3:imm2);
if BadReg(d) || n == 13 then UNPREDICTABLE;
Encoding A1 ARMv6T2, ARMv7
BFI ,,#,#
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
cond 0 1 1 1 1 1 0 msb Rd 1sb 0 0 1 Rn
if Rn == ‘1111’ then SEE BFC;
d = UInt(Rd); n = UInt(Rn); msbit = UInt(msb); lsbit = UInt(lsb);
if d == 15 then UNPREDICTABLE;
A8-48 Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. ARM DDI 0406B