@c
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@c
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@c COPYRIGHT (c) 1988-2002.
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@c COPYRIGHT (c) 1988-2002.
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@c On-Line Applications Research Corporation (OAR).
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@c On-Line Applications Research Corporation (OAR).
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@c All rights reserved.
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@c All rights reserved.
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@c
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@c
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@c adaintr.t,v 1.4 2002/01/17 21:47:44 joel Exp
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@c adaintr.t,v 1.4 2002/01/17 21:47:44 joel Exp
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@c
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@c
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@chapter Ada95 Interrupt Support
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@chapter Ada95 Interrupt Support
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@section Introduction
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@section Introduction
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This chapter describes what is required to enable Ada interrupt
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This chapter describes what is required to enable Ada interrupt
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and error exception handling when using GNAT over RTEMS.
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and error exception handling when using GNAT over RTEMS.
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The GNAT Ada95 interrupt support RTEMS was developed by
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The GNAT Ada95 interrupt support RTEMS was developed by
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Jiri Gaisler who also wrote this
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Jiri Gaisler who also wrote this
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chapter.
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chapter.
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@section Mapping Interrupts to POSIX Signals
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@section Mapping Interrupts to POSIX Signals
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In Ada95, interrupts can be attached with the interrupt_attach pragma.
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In Ada95, interrupts can be attached with the interrupt_attach pragma.
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For most systems, the gnat run-time will use POSIX signal to implement
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For most systems, the gnat run-time will use POSIX signal to implement
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the interrupt handling, mapping one signal per interrupt. For interrupts
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the interrupt handling, mapping one signal per interrupt. For interrupts
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to be propagated to the attached Ada handler, the corresponding signal
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to be propagated to the attached Ada handler, the corresponding signal
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must be raised when the interrupt occurs.
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must be raised when the interrupt occurs.
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The same mechanism is used to generate Ada error exceptions.
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The same mechanism is used to generate Ada error exceptions.
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Three error exceptions are defined: program, constraint and storage
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Three error exceptions are defined: program, constraint and storage
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error. These are generated by raising the predefined signals: SIGILL,
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error. These are generated by raising the predefined signals: SIGILL,
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SIGFPE and SIGSEGV. These signals should be raised when a spurious
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SIGFPE and SIGSEGV. These signals should be raised when a spurious
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or erroneous trap occurs.
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or erroneous trap occurs.
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To enable gnat interrupt and error exception support for a particular
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To enable gnat interrupt and error exception support for a particular
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bsp, the following has to be done:
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bsp, the following has to be done:
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@enumerate
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@enumerate
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@item Write an interrupt/trap handler that will raise the corresponding
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@item Write an interrupt/trap handler that will raise the corresponding
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signal depending on the interrupt/trap number.
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signal depending on the interrupt/trap number.
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@item Install the interrupt handler for all interrupts/traps that will be
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@item Install the interrupt handler for all interrupts/traps that will be
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handled by gnat (including spurious).
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handled by gnat (including spurious).
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@item At startup, gnat calls @code{__gnat_install_handler()}. The bsp
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@item At startup, gnat calls @code{__gnat_install_handler()}. The bsp
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must provide this function which installs the interrupt/trap handlers.
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must provide this function which installs the interrupt/trap handlers.
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@end enumerate
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@end enumerate
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Which cpu-interrupt will generate which signal is implementation
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Which cpu-interrupt will generate which signal is implementation
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defined. There are 32 POSIX signals (1 - 32), and all except the
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defined. There are 32 POSIX signals (1 - 32), and all except the
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three error signals (SIGILL, SIGFPE and SIGSEGV) can be used. I
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three error signals (SIGILL, SIGFPE and SIGSEGV) can be used. I
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would suggest to use the upper 16 (17 - 32) which do not
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would suggest to use the upper 16 (17 - 32) which do not
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have an assigned POSIX name.
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have an assigned POSIX name.
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Note that the pragma interrupt_attach will only bind a signal
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Note that the pragma interrupt_attach will only bind a signal
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to a particular Ada handler - it will not unmask the
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to a particular Ada handler - it will not unmask the
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interrupt or do any other things to enable it. This have to be
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interrupt or do any other things to enable it. This have to be
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done separately, typically by writing various device register.
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done separately, typically by writing various device register.
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@section Example Ada95 Interrupt Program
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@section Example Ada95 Interrupt Program
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An example program (@code{irq_test}) is included in the
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An example program (@code{irq_test}) is included in the
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Ada examples package to show how interrupts can be handled
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Ada examples package to show how interrupts can be handled
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in Ada95. Note that generation of the test interrupt
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in Ada95. Note that generation of the test interrupt
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(@code{irqforce.c}) is bsp specific and must be edited.
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(@code{irqforce.c}) is bsp specific and must be edited.
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NOTE: The @code{irq_test} example was written for the SPARC/ERC32
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NOTE: The @code{irq_test} example was written for the SPARC/ERC32
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BSP.
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BSP.
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@section Version Requirements
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@section Version Requirements
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With RTEMS 4.0, a patch was required to psignal.c in RTEMS
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With RTEMS 4.0, a patch was required to psignal.c in RTEMS
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sources (to correct a bug associated to the default action of
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sources (to correct a bug associated to the default action of
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signals 15-32). The SPARC/ERC32 RTEMS BSP includes the
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signals 15-32). The SPARC/ERC32 RTEMS BSP includes the
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@code{gnatsupp} subdirectory that can be used as an example
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@code{gnatsupp} subdirectory that can be used as an example
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for other BSPs.
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for other BSPs.
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With GNAT 3.11p, a patch is required for @code{a-init.c} to invoke
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With GNAT 3.11p, a patch is required for @code{a-init.c} to invoke
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the BSP specific routine that installs the exception handlers.
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the BSP specific routine that installs the exception handlers.
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