73 lines
1.7 KiB
Scheme
73 lines
1.7 KiB
Scheme
; Copyright (c) 1994 by Richard Kelsey. See file COPYING.
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(define (test x)
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(cond ((= x 1)
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(goto raise-exception 2))
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((= x 2)
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(goto raise-exception1 2 0))
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((= x 3)
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(goto raise-exception 3))
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((= x 4)
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(goto raise-exception1 4 0))))
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(define *code-pointer* 0)
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(define *stack* 0)
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(define (push x)
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(vector-set! *stack* 0 x)
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(set! *stack* (- *stack* 4)))
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(define (fetch-byte address)
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(byte-vector-ref address 0))
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(define (current-opcode code-args)
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(fetch-byte (- *code-pointer* (+ code-args 1))))
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(define (start-exception args)
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(push (current-opcode args)))
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(define (raise-exception args)
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(start-exception args)
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(goto raise 0))
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(define (raise-exception1 args a1)
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(start-exception args)
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(push a1)
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(goto raise 1))
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(define (raise n)
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(goto test n))
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(define-local-syntax (define-primitive id nargs)
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(let ((args (reverse (list-tail '(z y x) (- '3 nargs)))))
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`(define (,id . ,args)
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(call-primitively ,id . ,args))))
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(define-local-syntax (define-effect-primitive id nargs)
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(let ((args (reverse (list-tail '(z y x) (- '3 nargs)))))
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`(define (,id . ,args)
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(call-primitively ,id . ,args)
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(call-primitively undefined-value))))
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(define-primitive + 2)
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(define-primitive - 2)
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(define-primitive * 2)
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(define-primitive < 2)
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(define-primitive = 2)
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(define-primitive quotient 2)
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(define-primitive remainder 2)
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(define (unassigned) (call-primitively undefined-value))
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(define (byte-vector-ref vec index)
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(call-primitively byte-contents (+ vec index)))
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(define (byte-vector-set! vec index value)
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(call-primitively byte-set-contents! (+ vec index) value))
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(define (vector-set! vec index value)
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(call-primitively set-contents! (+ vec (* index 4)) value))
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