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53befeb700
(Not quite finished, the following will be done tomorrow. module/srfi/*.scm module/rnrs/*.scm module/scripts/*.scm testsuite/*.scm guile-readline/* )
51 lines
1.6 KiB
Scheme
51 lines
1.6 KiB
Scheme
;;; Guile Virtual Machine Object Code
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;; Copyright (C) 2001 Free Software Foundation, Inc.
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;;;; This library is free software; you can redistribute it and/or
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;;;; modify it under the terms of the GNU Lesser General Public
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;;;; License as published by the Free Software Foundation; either
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;;;; version 3 of the License, or (at your option) any later version.
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;;;;
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;;;; This library is distributed in the hope that it will be useful,
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;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;;;; Lesser General Public License for more details.
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;;;;
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;;;; You should have received a copy of the GNU Lesser General Public
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;;;; License along with this library; if not, write to the Free Software
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;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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;;; Code:
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(define-module (language objcode)
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#:export (encode-length decode-length))
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;;;
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;;; Variable-length interface
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;;;
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;; NOTE: decoded in vm_fetch_length in vm.c as well.
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(define (encode-length len)
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(cond ((< len 254) (u8vector len))
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((< len (* 256 256))
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(u8vector 254 (quotient len 256) (modulo len 256)))
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((< len most-positive-fixnum)
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(u8vector 255
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(quotient len (* 256 256 256))
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(modulo (quotient len (* 256 256)) 256)
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(modulo (quotient len 256) 256)
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(modulo len 256)))
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(else (error "Too long code length:" len))))
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(define (decode-length pop)
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(let ((x (pop)))
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(cond ((< x 254) x)
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((= x 254) (+ (ash x 8) (pop)))
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(else
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(let* ((b2 (pop))
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(b3 (pop))
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(b4 (pop)))
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(+ (ash x 24) (ash b2 16) (ash b3 8) b4))))))
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