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;; This file is part of scheme-GNUnet, a partial Scheme port of GNUnet.
;; Copyright (C) 2020, 2021 Maxime Devos <maxime.devos@student.kuleuven.be>
;;
;; scheme-GNUnet is free software: you can redistribute it and/or modify it
;; under the terms of the GNU Affero General Public License as published
;; by the Free Software Foundation, either version 3 of the License,
;; or (at your option) any later version.
;;
;; scheme-GNUnet is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; Affero General Public License for more details.
;;
;; You should have received a copy of the GNU Affero General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;
;; SPDX-License-Identifier: AGPL-3.0-or-later
;;
;; As a special exception to the GNU Affero General Public License,
;; the file may be relicensed under any license used for
;; most source code of GNUnet 0.13.1, or later versions, as published by
;; GNUnet e.V.
;; Author: Maxime Devos
;; Source: gnu/gnunet/utils/netstruct.scm
;; Brief: C-like structures as syntactical sugar
;; TODO: guile-bytestructures is more standard
;; TODO: testing
(library (gnu gnunet utils netstruct)
(export u8vector u8
u16/big u32/big u64/big
u16/little u32/little u64/little
structure/packed
wrap-reader-setter
sizeof offset select read% set%!)
(import (rnrs base)
(srfi srfi-26)
(gnu gnunet utils bv-slice))
;; Methods (not all might be available)
;; :sizeof (): size of structure
;; :sizeof (x ...): sizeof of field x (& repeat) in structure
;; :offset (x ...): offset of field x (& repeat) in structure
;; :select (x ...):
;; select field x in structure, repeat for ... (function between slices)
;; :reader (x ...):
;; select field x (& repeat), and parse the found value
;; (only for very simple values usually)
;; :setter (x ...):
;; select field x (& repeat), and mutate the found value
;;
;; The use of sizeof, offset, select, read & write is preferred
(define (slice-length-verifying-id length)
(lambda (slice)
(assert (= (slice-length slice) length))
slice))
(define (verify-index i length)
(assert (and (integer? i)
(exact? i)
(<= 0 i)
(< i length))))
(define (reader-also-check-length length reader)
(lambda (slice)
(assert (= (slice-length slice) length))
(reader slice)))
(define (setter-also-check-length length setter)
(lambda (slice x)
(assert (= (slice-length slice) length))
(setter slice x)))
(define-syntax standard-select
(syntax-rules ()
((_ % indices)
(let ((stot (% :sizeof ()))
(offset (% :offset indices))
(size (% :sizeof indices)))
(lambda (slice)
(assert (= stot (slice-length slice)))
(slice-slice slice offset size))))))
(define-syntax u8vector
(syntax-rules ()
((_ length)
(syntax-rules (:sizeof :offset :select :reader :setter)
((% :sizeof ()) length)
((% :sizeof (i))
(begin (verify-index i length)
1))
((% :offset ()) 0)
((% :offset (i))
(begin (verify-index i length)
i))
((% :select indices)
(let-syntax ((%-self (u8vector length)))
(standard-select %-self indices)))
((% :reader indices)
(let-syntax ((self (u8vector length)))
(let ((s (self :select indices))
(r (u8 :reader ())))
(lambda (slice)
(r (s slice))))))
((% :setter indices)
(let-syntax ((self (u8vector length)))
(let ((se (self :select indices))
(ss (u8 :setter indices)))
(lambda (slice v)
(ss (se slice) v)))))))))
(define-syntax unsigned-N-bytes
(syntax-rules ()
((_ length slice-ref slice-set!)
(syntax-rules (:sizeof :offset :select :reader :setter)
((% :sizeof ()) length)
((% :offset ()) 0)
((% :select ()) (slice-verifying-id length))
((% :reader ())
(reader-also-check-length length (cute slice-ref <> 0)))
((% :setter ())
(setter-also-check-length length (cute slice-set! <> 0 <>)))))))
(define-syntax define-unsigned-N-bytes
(syntax-rules ()
((_ ((length slice-ref slice-set!)
(name-big name-little)) ...)
(begin
(begin
(define-syntax name-big
(unsigned-N-bytes
length
(cute slice-ref <> 0 (endianness big))
(cute slice-set! <> 0 (endianness big) <>)))
(define-syntax name-little
(unsigned-N-bytes
length
(cute slice-ref <> 0 (endianness little))
(cute slice-set! <> 0 (endianness little) <>))))
...))))
(define-syntax u8 (unsigned-N-bytes 1 slice-u8-ref slice-u8-set!))
(define-unsigned-N-bytes
((2 slice-u16-ref slice-u16-set!) (u16/big u16/little))
((4 slice-u32-ref slice-u32-set!) (u32/big u32/little))
((8 slice-u64-ref slice-u64-set!) (u64/big u64/little)))
;; FIXME ideally field names would be symbols,
;; not strings, but I can't get this to work
;; with symbols.
(define-syntax structure/packed
(syntax-rules ::: ()
((_)
(syntax-rules (:sizeof :offset :select)
((% :sizeof ()) 0)
((% :offset ()) 0)
((% :select ()) (slice-verifying-id 0))))
((_ (field-name field-type) (field-name* field-type*) :::)
(syntax-rules (:sizeof :offset :select
:reader-for-field :setter-for-field
:reader :setter)
((% :sizeof ())
(+ (field-type :sizeof ())
(field-type* :sizeof ())
:::))
((% :sizeof (field-name etc ...))
(field-type :sizeof (etc ...)))
((% :sizeof (field-name* etc ...))
(field-type* :sizeof (etc ...)))
:::
((% :offset ()) 0)
((% :offset (field-name etc ...))
(field-type :offset (etc ...)))
((% :offset (other-field-name etc ...))
(+ (field-type :sizeof ())
(let-syntax ((tail
(structure/packed
(field-name* field-type*) :::)))
(tail :offset (other-field-name etc ...)))))
((% :select indices)
(let-syntax ((%-self (structure/packed
(field-name field-type)
(field-name* field-type*) :::)))
(standard-select %-self indices)))
((% :reader-for-field field-name rest)
(field-type :reader rest))
((% :reader-for-field field-name* rest)
(field-type* :reader rest))
:::
((% :setter-for-field field-name rest)
(field-type :setter rest))
((% :setter-for-field field-name* rest)
(field-type* :setter rest))
:::
((% :reader (any-field-name . rest))
(let-syntax ((self
(structure/packed
(field-name field-type)
(field-name* field-type*)
:::)))
(let ((fs (self :select (any-field-name)))
(fr (self :reader-for-field any-field-name rest)))
(lambda (slice)
(fr (fs slice))))))
((% :setter (any-field-name . rest))
(let-syntax ((self
(structure/packed
(field-name field-type)
(field-name* field-type*)
:::)))
(let ((fsel (self :select (any-field-name)))
(fset (self :setter-for-field any-field-name rest)))
(lambda (slice x)
(fset (fsel slice) x)))))))))
(define-syntax wrap-reader-setter
(syntax-rules ()
((_ internal internal->wrap wrap->internal)
(syntax-rules (:sizeof :offset :reader :setter)
((% :sizeof rest)
(internal :sizeof rest))
((% :offset ())
(internal :offset ()))
((% :reader ())
(let ((internal-reader (internal :reader ()))
(internal->wrap/expanded internal->wrap))
(lambda (slice)
(internal->wrap (internal-reader slice)))))
((% :setter ())
(let ((internal-setter (internal :setter ()))
(wrap->internal/expanded wrap->internal))
(lambda (slice wrapped)
(internal-setter slice (wrap->internal wrapped)))))))))
(define-syntax syntax-method
(syntax-rules ()
((_ () method)
(syntax-rules ()
((_ struct arg)
(struct method arg))))
((_ (()) method)
(syntax-rules ()
((_ struct arg arg*)
((struct method arg) arg*))))
((_ (() ()) method)
(syntax-rules ()
((_ struct arg arg* arg**)
((struct method arg) arg* arg**))))))
(define-syntax sizeof (syntax-method () :sizeof))
(define-syntax offset (syntax-method () :offset))
(define-syntax select (syntax-method (()) :select))
(define-syntax read% (syntax-method (()) :reader))
(define-syntax set%! (syntax-method (() ()) :setter)))
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