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;;; Copyright (C) 2010-2011,2013-2014,2024 Free Software Foundation, Inc.
;;;
;;; This library is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; This library 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
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
(define-module (system foreign)
#:use-module (ice-9 match)
#:use-module (rnrs bytevectors)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-9 gnu)
#:use-module (srfi srfi-11)
#:use-module (system base target)
#:export (void
float double
complex-float complex-double
short
unsigned-short
int unsigned-int long unsigned-long size_t ssize_t ptrdiff_t
int8 uint8
uint16 int16
uint32 int32
uint64 int64
intptr_t uintptr_t
sizeof alignof
%null-pointer
null-pointer?
pointer?
make-pointer
pointer->scm
scm->pointer
pointer-address
pointer->bytevector
bytevector->pointer
set-pointer-finalizer!
dereference-pointer
string->pointer
pointer->string
pointer->procedure
;; procedure->pointer (see below)
read-c-struct write-c-struct
make-c-struct parse-c-struct
define-wrapped-pointer-type))
(eval-when (expand load eval)
(load-extension (string-append "libguile-" (effective-version))
"scm_init_foreign"))
;;;
;;; Pointers.
;;;
(define (null-pointer? pointer)
"Return true if POINTER is the null pointer."
(= (pointer-address pointer) 0))
(if (defined? 'procedure->pointer)
(export procedure->pointer))
;;;
;;; Structures.
;;;
(define-syntax compile-time-eval
(lambda (stx)
"Evaluate the target-dependent expression EXP at compile-time if we are
not cross-compiling; otherwise leave it to be evaluated at run-time."
(syntax-case stx ()
((_ exp)
(if (equal? (target-type) %host-type)
#`(quote
#,(datum->syntax #'here
(primitive-eval (syntax->datum #'exp))))
#'exp)))))
;; Note that in a cross-compiled Guile, the host and the target may have
;; different values of, say, `long'. However the explicitly-sized types
;; int8, float, etc have the same value on all platforms. sizeof on
;; these types is also a target-invariant primitive. alignof is notably
;; *not* target-invariant.
(define-syntax switch/compile-time-keys
(syntax-rules (else)
((_ x (k expr) ... (else alt))
(let ((t x))
(cond
((eq? t (compile-time-eval k)) expr)
...
(else alt))))))
(define-syntax-rule (align off alignment)
(1+ (logior (1- off) (1- alignment))))
(define bytevector-pointer-ref
(case (sizeof '*)
((8) (lambda (bv offset)
(make-pointer (bytevector-u64-native-ref bv offset))))
((4) (lambda (bv offset)
(make-pointer (bytevector-u32-native-ref bv offset))))
(else (error "what machine is this?"))))
(define bytevector-pointer-set!
(case (sizeof '*)
((8) (lambda (bv offset ptr)
(bytevector-u64-native-set! bv offset (pointer-address ptr))))
((4) (lambda (bv offset ptr)
(bytevector-u32-native-set! bv offset (pointer-address ptr))))
(else (error "what machine is this?"))))
(define-syntax-rule (define-complex-accessors (read write) (%read %write size))
(begin
(define (read bv offset)
(make-rectangular
(%read bv offset)
(%read bv (+ offset size))))
(define (write bv offset val)
(%write bv offset (real-part val))
(%write bv (+ offset size) (imag-part val)))))
(define-complex-accessors
(bytevector-complex-single-native-ref bytevector-complex-single-native-set!)
(bytevector-ieee-single-native-ref bytevector-ieee-single-native-set! 4))
(define-complex-accessors
(bytevector-complex-double-native-ref bytevector-complex-double-native-set!)
(bytevector-ieee-double-native-ref bytevector-ieee-double-native-set! 8))
(define-syntax-rule (read-field %bv %offset %type)
(let ((bv %bv)
(offset %offset)
(type %type))
(define-syntax-rule (%read type reader)
(let* ((offset (align offset (compile-time-eval (alignof type))))
(val (reader bv offset)))
(values val
(+ offset (compile-time-eval (sizeof type))))))
(define-syntax-rule (dispatch-read type (%%type reader) (... ...))
(switch/compile-time-keys
type
(%%type (%read %%type reader))
(... ...)
(else
(let ((offset (align offset (alignof type))))
(values (%read-c-struct bv offset type)
(+ offset (sizeof type)))))))
(dispatch-read
type
(int8 bytevector-s8-ref)
(uint8 bytevector-u8-ref)
(int16 bytevector-s16-native-ref)
(uint16 bytevector-u16-native-ref)
(int32 bytevector-s32-native-ref)
(uint32 bytevector-u32-native-ref)
(int64 bytevector-s64-native-ref)
(uint64 bytevector-u64-native-ref)
(float bytevector-ieee-single-native-ref)
(double bytevector-ieee-double-native-ref)
(complex-float bytevector-complex-single-native-ref)
(complex-double bytevector-complex-double-native-ref)
('* bytevector-pointer-ref))))
(define-syntax-rule (read-c-struct %bv %offset ((field type) ...) k)
(let ((bv %bv)
(offset %offset)
(size (compile-time-eval (sizeof (list type ...)))))
(unless (<= (bytevector-length bv) (+ offset size))
(error "destination bytevector too small"))
(let*-values (((field offset)
(read-field bv offset (compile-time-eval type)))
...)
(k field ...))))
(define-syntax-rule (write-field %bv %offset %type %value)
(let ((bv %bv)
(offset %offset)
(type %type)
(value %value))
(define-syntax-rule (%write type writer)
(let ((offset (align offset (compile-time-eval (alignof type)))))
(writer bv offset value)
(+ offset (compile-time-eval (sizeof type)))))
(define-syntax-rule (dispatch-write type (%%type writer) (... ...))
(switch/compile-time-keys
type
(%%type (%write %%type writer))
(... ...)
(else
(let ((offset (align offset (alignof type))))
(%write-c-struct bv offset type value)
(+ offset (sizeof type))))))
(dispatch-write
type
(int8 bytevector-s8-set!)
(uint8 bytevector-u8-set!)
(int16 bytevector-s16-native-set!)
(uint16 bytevector-u16-native-set!)
(int32 bytevector-s32-native-set!)
(uint32 bytevector-u32-native-set!)
(int64 bytevector-s64-native-set!)
(uint64 bytevector-u64-native-set!)
(float bytevector-ieee-single-native-set!)
(double bytevector-ieee-double-native-set!)
(complex-float bytevector-complex-single-native-set!)
(complex-double bytevector-complex-double-native-set!)
('* bytevector-pointer-set!))))
(define-syntax-rule (write-c-struct %bv %offset ((field type) ...))
(let ((bv %bv)
(offset %offset)
(size (compile-time-eval (sizeof (list type ...)))))
(unless (<= (bytevector-length bv) (+ offset size))
(error "destination bytevector too small"))
(let* ((offset (write-field bv offset (compile-time-eval type) field))
...)
(values))))
;; Same as write-c-struct, but with run-time dispatch.
(define (%write-c-struct bv offset types vals)
(let lp ((offset offset) (types types) (vals vals))
(match types
(() (match vals
(() #t)
(_ (error "too many values" vals))))
((type . types)
(match vals
((val . vals)
(lp (write-field bv offset type val) types vals))
(() (error "too few values" vals)))))))
;; Same as read-c-struct, but with run-time dispatch.
(define (%read-c-struct bv offset types)
(let lp ((offset offset) (types types))
(match types
(() '())
((type . types)
(call-with-values (lambda () (read-field bv offset type))
(lambda (val offset)
(cons val (lp offset types))))))))
(define (make-c-struct types vals)
(let ((bv (make-bytevector (sizeof types) 0)))
(%write-c-struct bv 0 types vals)
(bytevector->pointer bv)))
(define (parse-c-struct foreign types)
(%read-c-struct (pointer->bytevector foreign (sizeof types)) 0 types))
;;;
;;; Wrapped pointer types.
;;;
(define-syntax define-wrapped-pointer-type
(lambda (stx)
"Define helper procedures to wrap pointer objects into Scheme
objects with a disjoint type. Specifically, this macro defines PRED, a
predicate for the new Scheme type, WRAP, a procedure that takes a
pointer object and returns an object that satisfies PRED, and UNWRAP
which does the reverse. PRINT must name a user-defined object printer."
(syntax-case stx ()
((_ type-name pred wrap unwrap print)
(with-syntax ((%wrap (datum->syntax #'wrap (gensym "wrap"))))
#'(begin
(define-record-type type-name
(%wrap pointer)
pred
(pointer unwrap))
(define wrap
;; Use a weak hash table to preserve pointer identity, i.e.,
;; PTR1 == PTR2 <-> (eq? (wrap PTR1) (wrap PTR2)).
(let ((ptr->obj (make-weak-value-hash-table 3000)))
(lambda (ptr)
(or (hash-ref ptr->obj ptr)
(let ((o (%wrap ptr)))
(hash-set! ptr->obj ptr o)
o)))))
(set-record-type-printer! type-name print)))))))
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