5.4.3. BX

Branch, and optionally exchange instruction set.

Syntax

BX Rm

where:

Rm

is an ARM register containing the address to branchto.

Bit 0 of Rm is not used as part of the address.

If bit 0 of Rm is clear:

  • bit 1 must also be clear

  • the instruction clears the T flag in the CPSR, and the code at the destination is interpreted as ARM code.

Usage

The BX instruction causes a branch to the address held in Rm, and changes instruction set to Thumb if bit 0 of Rm is set.

Architectures

This instruction is available in all T variants of the ARM architecture.

Examples

    BX  r5
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