RealView® Developer Kit Assembler Guide 4.10.2. SWI

4.10.2. SWI

SoftWare Interrupt.

Syntax

SWI{cond} immed

where:

cond

is an optional condition code (see Conditional execution).

immed

is an expression evaluating to an integer in the range:

0 to 2²⁴–1 (a 24-bit value) in an ARM instruction
0-255 (an 8-bit value) in a 16-bit Thumb instruction.

Usage

The SWI instruction causes a SWI exception. This means that the processor mode changes to Supervisor, the CPSR is saved to the Supervisor mode SPSR, and execution branches to the SWI vector.

immed is ignored by the processor. However, it can be retrieved by the exception handler to determine what service is being requested.

Condition flags

This instruction does not change the flags.

Architectures

This ARM instruction is available in all versions of the ARM architecture.

This 16-bit Thumb instruction is available in all T variants of the ARM architecture.

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