17.2.12 Isr Function Attribute

The isr(type) attribute instructs the compiler to generate prologue and epilogue code for the function as an interrupt handler function, as described in Interrupts. For Cortex-A devices, the type argument specifies the type of the interrupt, which may be one of the identifiers irq, fiq, abort, undef or swi, in lowercase or uppercase. Any argument specified is ignore when building for Cortex-M devices.