BBC.W18 — Branch if Bit Clear

Instruction Word

Slot
ae2_slot0
6
3
6
2
6
1
6
0
5
9
5
8
5
7
5
6
5
5
5
4
5
3
5
2
5
1
5
0
4
9
4
8
4
7
4
6
4
5
4
4
4
3
4
2
4
1
4
0
3
9
3
8
3
7
3
6
3
5
3
4
3
3
3
2
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
9876543210
Format ae_format2 - 64 bit(s)0000 1110
BBC.W18 00 0011
s 3210
t 3210
xt_wbr18_imm 1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
987654 3210

Assembler Syntax

BBC.W18 as, at, label

Description

(please consult the Xtensa ® Instruction Set Architecture Reference Manual for any cross references and additional information)

The operation of the BBC.W18 branch instruction is very similar to the Xtensa ISA instruction BBC. The only difference is that the BBC.W18 instruction provides for a wider immediate field of 18 bits to encode the branch offset, thus enabling branches over a greater address range.

Operation

b ← AR[t]4..0 xor msbFirst5
if AR[s]b = 0 then
	nextPC ← PC + (imm8724||imm8) + 4
endif

Exceptions

EveryInstR Group (see EveryInstR Group:)