60 lines
1.5 KiB
Scheme
60 lines
1.5 KiB
Scheme
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; Copyright (c) 1993, 1994 Richard Kelsey and Jonathan Rees. See file COPYING.
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; --------------------
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; Fake interrupt and exception system.
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; This needs to be reconciled with alt/primitives.scm.
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(define (with-exceptions thunk)
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(with-handler
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(lambda (c punt)
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(cond ((and (exception? c)
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(procedure? (get-exception-handler)))
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(handle-exception-carefully c))
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((interrupt? c)
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(if (not (deal-with-interrupt c))
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(punt)))
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;; ((vm-return? c)
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;; (vm-return (cadr c)))
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(else
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(punt))))
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thunk))
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(define (handle-exception-carefully c)
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(display "(Exception: ") (write c) (display ")") (newline)
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(noting-exceptional-context c
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(lambda ()
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(raise-exception (exception-opcode c)
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(exception-arguments c)))))
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(define (noting-exceptional-context c thunk)
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(call-with-current-continuation
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(lambda (k)
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;; Save for future inspection, just in case.
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(set! *exceptional-context* (cons c k))
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(thunk))))
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(define *exceptional-context* #f)
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(define (deal-with-interrupt c)
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(noting-exceptional-context c
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(lambda ()
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(maybe-handle-interrupt
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(if (and (pair? (cdr c)) (integer? (cadr c)))
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(cadr c)
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(enum interrupt keyboard))))))
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; (define (poll-for-interrupts) ...)
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; Get the whole thing started
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(define (?start-with-exceptions entry-point arg)
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(with-exceptions
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(lambda ()
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(?start entry-point arg))))
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(define (in struct form)
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(eval form (structure-package struct)))
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