b.w

Branch (Wide)

B.W <label>

Thumb-2 32-bit Unconditional Branch (large range).

Details

Thumb-2 32-bit unconditional branch with large range (±16 MB). Computes the target address by sign-extending the immediate offset (formed from S, imm10, J1, J2, imm11) and adding it to PC. No condition flags are affected; no registers are modified except PC.

Pseudocode Operation

if ConditionPassed() then
  offset ← SignExtend(S || imm10 || J1 || J2 || imm11, 24)
  PC ← PC + (offset << 1)

Example

B.W label

Encoding

Binary Layout

11110

imm10

imm11

Format Thumb Branch

Opcode 0xF0009000

Extension T32 (Thumb2)

Operands

label
Label

Reference (Arm AArch32 ISA)

Instruction Forms

Encoding	Instruction	ISA	Bit pattern
0x0A000000	B{<c>}{<q>} <label>	A32	cond \| 101 \| 0 \| imm24
0xD000	B<c>{<q>} <label>	T32	1101 \| cond \| imm8
0xE000	B{<c>}{<q>} <label>	T32	11100 \| imm11
0xF0008000	B<c>.W <label>	T32	11110 \| S \| cond \| imm6 \| 10 \| J1 \| 0 \| J2 \| imm11
0xF0009000	B{<c>}.W <label>	T32	11110 \| S \| imm10 \| 10 \| J1 \| 1 \| J2 \| imm11

Description

Branch causes a branch to a target address.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    BranchWritePC(PC + imm32, BranchType_DIR);