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diff --git a/doc/bsp_howto/adaintr.t b/doc/bsp_howto/adaintr.t new file mode 100644 index 0000000000..ee87156e42 --- /dev/null +++ b/doc/bsp_howto/adaintr.t @@ -0,0 +1,77 @@ +@c +@c COPYRIGHT (c) 1988-1998. +@c On-Line Applications Research Corporation (OAR). +@c All rights reserved. +@c +@c $Id$ +@c + +@chapter Ada95 Interrupt Support + +@section Introduction + +This chapter describes what is required to enable Ada interrupt +and error exception handling when using GNAT over RTEMS. + +The GNAT Ada95 interrupt support RTEMS was developed by +Jiri Gaisler <jgais@@ws.estec.esa.nl> who also wrote this +chapter. + +@section Mapping Interrupts to POSIX Signals + +In Ada95, interrupts can be attached with the interrupt_attach pragma. +For most systems, the gnat run-time will use POSIX signal to implement +the interrupt handling, mapping one signal per interrupt. For interrupts +to be propagated to the attached Ada handler, the corresponding signal +must be raised when the interrupt occurs. + +The same mechanism is used to generate Ada error exceptions. +Three error exceptions are defined: program, constraint and storage +error. These are generated by raising the predefined signals: SIGILL, +SIGFPE and SIGSEGV. These signals should be raised when a spurious +or erroneous trap occurs. + +To enable gnat interrupt and error exception support for a particular +bsp, the following has to be done: + +@enumerate + +@item Write an interrupt/trap handler that will raise the corresponding +signal depending on the interrupt/trap number. + +@item Install the interrupt handler for all interrupts/traps that will be +handled by gnat (including spurious). + +@item At startup, gnat calls @code{__gnat_install_handler()}. The bsp +must provide this function which installs the interrupt/trap handlers. + +@end enumerate + +Which cpu-interrupt will generate which signal is implementation +defined. There are 32 POSIX signals (1 - 32), and all except the +three error signals (SIGILL, SIGFPE and SIGSEGV) can be used. I +would suggest to use the upper 16 (17 - 32) which do not +have an assigned POSIX name. + +Note that the pragma interrupt_attach will only bind a signal +to a particular Ada handler - it will not unmask the +interrupt or do any other things to enable it. This have to be +done separately, typically by writing various device register. + +@section Example Ada95 Interrupt Program + +An example program is available to show how interrupts +can be handled in Ada95. Note that generation of the test +interrupt (irqforce.c) is bsp specific and must be edited. + +@section Version Requirements + +With RTEMS 4.0, a patch was required to psignal.c in RTEMS +sources (to correct a bug associated to the default action of +signals 15-32). The SPARC/ERC32 RTEMS BSP includes the +@code{gnatsupp} subdirectory that can be used as an example +for other BSPs. + +With GNAT 3.11p, a patch is required for @code{a-init.c} to invoke +the BSP specific routine that installs the exception handlers. + |