Epiphany Attributes (Using the GNU Compiler Collection (GCC))

#### 6.4.2.9 Epiphany Attributes ¶

These attributes are supported by the Epiphany back end:

`disinterrupt` ¶

  This attribute applies to functions.

  It causes the compiler to emit instructions to disable interrupts for the duration of the given function.

`forwarder_section` ¶

  This attribute applies to functions.

  It modifies the behavior of an interrupt handler. The interrupt handler may be in external memory which cannot be reached by a branch instruction, so generate a local memory trampoline to transfer control. The single parameter identifies the section where the trampoline is placed.

`interrupt` ¶

  This attribute applies to functions.

  It indicates that the specified function is an interrupt handler. The compiler generates function entry and exit sequences suitable for use in an interrupt handler when this attribute is present. It may also generate a special section with code to initialize the interrupt vector table.

  On Epiphany targets one or more optional parameters can be added like this:

      void __attribute__ ((interrupt ("dma0, dma1"))) universal_dma_handler ();

  Permissible values for these parameters are: `reset`, `software_exception`, `page_miss`, `timer0`, `timer1`, `message`, `dma0`, `dma1`, `wand` and `swi`. Multiple parameters indicate that multiple entries in the interrupt vector table should be initialized for this function, i.e. for each parameter name, a jump to the function is emitted in the section ivt_entry_name. The parameter(s) may be omitted entirely, in which case no interrupt vector table entry is provided.

  Note that interrupts are enabled inside the function unless the `disinterrupt` attribute is also specified.

  The following examples are all valid uses of these attributes on Epiphany targets:

      void __attribute__ ((interrupt)) universal_handler ();
      void __attribute__ ((interrupt ("dma1"))) dma1_handler ();
      void __attribute__ ((interrupt ("dma0, dma1")))
        universal_dma_handler ();
      void __attribute__ ((interrupt ("timer0"), disinterrupt))
        fast_timer_handler ();
      void __attribute__ ((interrupt ("dma0, dma1"),
                           forwarder_section ("tramp")))
        external_dma_handler ();

`long_call` ¶
`short_call`

  These attributes apply to functions.

  They specify how the associated function is called. These attributes override the `-mlong-calls` (see Adapteva Epiphany Options) command-line switch and `#pragma long_calls` settings.