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< title > foreign-c a portable foreign function interface for R7RS
Schemes - 0.10.0< / title >
< style >
table { width : 250 % ; }
nav { float : left ; width : 20 % ; }
main { float : right ; width : 80 % ; }
pre { background-color : lightgrey ; }
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< / head >
< body >
< h1 id = "foreign-c" > foreign-c< / h1 >
< p > foreign-c is a C foreign function interface (FFI) library for
R7RS Schemes. It is portable in the sense that it supports
multiple implementations, as opposed to being portable by
conforming to some specification.< / p >
< p > < a href = "https://sr.ht/~retropikzel/foreign-c/trackers" > Issue
tracker< / a > < / p >
< p > < a href = "https://sr.ht/~retropikzel/foreign-c/lists" > Maling
lists< / a > < / p >
< p > < a
href = "https://jenkins.scheme.org/job/foreign_c/job/foreign-c/" > Jenkins< / a > < / p >
< ul >
< li > < a href = "#installation" > Installation< / a > < / li >
< li > < a href = "#documentation" > Documentation< / a >
< ul >
< li > < a href = "#types" > Types< / a > < / li >
< li > < a href = "#primitives-1" > Primitives 1< / a >
< ul >
< li > c-type-size< / li >
< li > define-c-library< / li >
< li > define-c-procedure< / li >
< li > c-bytevector?< / li >
< li > c-bytevector-u8-set!< / li >
< li > c-bytevector-u8-ref< / li >
< li > c-bytevector-pointer-set!< / li >
< li > c-bytevector-pointer-ref< / li >
< / ul > < / li >
< li > < a href = "#primitives-2" > Primitives 2< / a >
< ul >
< li > define-c-callback< / li >
< / ul > < / li >
< li > < a href = "#c-bytevector" > c-bytevector< / a >
< ul >
< li > make-c-null< / li >
< li > c-null?< / li >
< li > c-free< / li >
< li > make-c-bytevector< / li >
< li > call-with-address-of< / li >
< li > native-endianness< / li >
< li > c-bytevector-s8-set!< / li >
< li > c-bytevector-s8-ref< / li >
< li > c-bytevector-s16-set!< / li >
< li > c-bytevector-s16-ref< / li >
< li > c-bytevector-s16-native-set!< / li >
< li > c-bytevector-s16-native-ref< / li >
< li > c-bytevector-u16-set!< / li >
< li > c-bytevector-u16-ref< / li >
< li > c-bytevector-u16-native-set!< / li >
< li > c-bytevector-u16-native-ref< / li >
< li > c-bytevector-s32-set!< / li >
< li > c-bytevector-s32-ref< / li >
< li > c-bytevector-s32-native-set!< / li >
< li > c-bytevector-s32-native-ref< / li >
< li > c-bytevector-u32-set!< / li >
< li > c-bytevector-u32-ref< / li >
< li > c-bytevector-u32-native-set!< / li >
< li > c-bytevector-u32-native-ref< / li >
< li > c-bytevector-s64-set!< / li >
< li > c-bytevector-s64-ref< / li >
< li > c-bytevector-s64-native-set!< / li >
< li > c-bytevector-s64-native-ref< / li >
< li > c-bytevector-u64-set!< / li >
< li > c-bytevector-u64-ref< / li >
< li > c-bytevector-u64-native-set!< / li >
< li > c-bytevector-u64-native-ref< / li >
< li > c-bytevector-sint-set!< / li >
< li > c-bytevector-sint-ref< / li >
< li > c-bytevector-uint-set!< / li >
< li > c-bytevector-uint-ref< / li >
< li > c-bytevector-ieee-single-set!< / li >
< li > c-bytevector-ieee-single-native-set!< / li >
< li > c-bytevector-ieee-single-ref< / li >
< li > c-bytevector-ieee-single-native-ref< / li >
< li > c-bytevector-ieee-double-set!< / li >
< li > c-bytevector-ieee-double-native-set!< / li >
< li > c-bytevector-ieee-double-ref< / li >
< li > c-bytevector-ieee-double-native-ref< / li >
< li > bytevector-> c-bytevector< / li >
< li > c-bytevector-> bytevector< / li >
< li > string-> c-utf8< / li >
< li > c-utf8-> string< / li >
< / ul > < / li >
< li > < a href = "#environment-variables" > Environment
variables< / a > < / li >
< / ul > < / li >
< / ul >
< h2 id = "implementation-support-tables" > Implementation support
tables< / h2 >
< h3 id = "primitives-1-table" > Primitives 1 table< / h3 >
< table >
< colgroup >
< col style = "width: 13%" / >
< col style = "width: 10%" / >
< col style = "width: 16%" / >
< col style = "width: 15%" / >
< col style = "width: 16%" / >
< col style = "width: 11%" / >
< col style = "width: 16%" / >
< / colgroup >
< thead >
< tr class = "header" >
< th > < / th >
< th style = "text-align: center;" > c-type-size< / th >
< th style = "text-align: center;" > c-bytevector-u8-set!< / th >
< th style = "text-align: center;" > c-bytevector-u8-ref< / th >
< th style = "text-align: center;" > define-c-library< / th >
< th style = "text-align: center;" > c-bytevector?< / th >
< th style = "text-align: center;" > define-c-procedure< / th >
< / tr >
< / thead >
< tbody >
< tr class = "odd" >
< td > < strong > Chibi< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "even" >
< td > < strong > Chicken< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > < strong > Gauche< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "even" >
< td > < strong > Guile< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > < strong > Kawa< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "even" >
< td > < strong > Mosh< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > < strong > Racket< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "even" >
< td > < strong > Saggittarius< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > < strong > Stklos< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "even" >
< td > < strong > Ypsilon< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< / tbody >
< / table >
< h3 id = "primitives-2-table" > Primitives 2 table< / h3 >
< table >
< thead >
< tr class = "header" >
< th > < / th >
< th style = "text-align: center;" > define-c-callback< / th >
< / tr >
< / thead >
< tbody >
< tr class = "odd" >
< td > Chibi< / td >
< td style = "text-align: center;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Chicken< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > Gauche< / td >
< td style = "text-align: center;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Guile< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > Kawa< / td >
< td style = "text-align: center;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Mosh< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > < strong > Racket< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "even" >
< td > < strong > Saggittarius< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< tr class = "odd" >
< td > Stklos< / td >
< td style = "text-align: center;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Ypsilon< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< / tr >
< / tbody >
< / table >
< h3 id = "test-files-pass" > Test files pass< / h3 >
< table >
< thead >
< tr class = "header" >
< th > < / th >
< th style = "text-align: center;" > primitives.scm< / th >
< th style = "text-align: center;" > addressof.scm< / th >
< th style = "text-align: right;" > callback.scm< / th >
< / tr >
< / thead >
< tbody >
< tr class = "odd" >
< td > Chibi< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Chicken< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > X< / td >
< / tr >
< tr class = "odd" >
< td > Gauche< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Guile< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > X< / td >
< / tr >
< tr class = "odd" >
< td > Kawa< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > < / td >
< / tr >
< tr class = "even" >
< td > Mosh< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > < / td >
< / tr >
< tr class = "odd" >
< td > Racket< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > < / td >
< td style = "text-align: right;" > < / td >
< / tr >
< tr class = "even" >
< td > < strong > Saggittarius< / strong > < / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > X< / td >
< / tr >
< tr class = "odd" >
< td > Stklos< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > < / td >
< / tr >
< tr class = "even" >
< td > Ypsilon< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: center;" > X< / td >
< td style = "text-align: right;" > < / td >
< / tr >
< / tbody >
< / table >
< h2 id = "installation" > Installation< / h2 >
< p > Eithe download the latest release from < a
href = "https://git.sr.ht/~retropikzel/foreign-c/refs" > https://git.sr.ht/~retropikzel/foreign-c/refs< / a >
or git clone, preferably with a tag, and copy the
< em > foreign< / em > directory to your library directory.< / p >
< p > Example assuming libraries in directory < em > snow< / em > :< / p >
< pre > < code > git clone https://git.sr.ht/~retropikzel/foreign-c --branch LATEST_VERSION
mkdir -p snow
cp -r foreign-c/foreign snow/
make -C snow/foreign/c SCHEME_IMPLEMENTATION_NAME< / code > < / pre >
< p > With most implementations the make command does not compile
anything. When that is the case it will say “Nothing to build on
SCHEME_IMPLEMENTATION_NAME.”< / p >
< h2 id = "documentation" > Documentation< / h2 >
< h3 id = "types" > Types< / h3 >
< p > Types are given as symbols, for example ’
’ < / p >
< ul >
< li > int8< / li >
< li > uint8< / li >
< li > int16< / li >
< li > uint16< / li >
< li > int32< / li >
< li > uint32< / li >
< li > int64< / li >
< li > uint64< / li >
< li > char< / li >
< li > unsigned-char< / li >
< li > short< / li >
< li > unsigned-short< / li >
< li > int< / li >
< li > unsigned-int< / li >
< li > long< / li >
< li > unsigned-long< / li >
< li > float< / li >
< li > double< / li >
< li > pointer
< ul >
< li > c-bytevector on Scheme side< / li >
< / ul > < / li >
< li > callback
< ul >
< li > Callback function< / li >
< / ul > < / li >
< li > void
< ul >
< li > Can not be argument type, only return type< / li >
< / ul > < / li >
< / ul >
< h3 id = "primitives-1" > Primitives 1< / h3 >
< p > (< strong > c-type-size< / strong > < em > type< / em > )< / p >
< p > Returns the size of given C type.< / p >
< p > (< strong > define-c-library< / strong > < em > scheme-name< / em >
< em > headers< / em > < em > object-name< / em > < em > options< / em > )< / p >
< p > Takes a scheme-name to bind the library to, list of C headers
as strings, shared-object name and options.< / p >
< p > The C header strings should not contain “< ” or “> ”,
they are added automatically.< / p >
< p > The name of the shared object should not contain suffix like
.so or .dll. Nor should it contain any prefix like “lib”.< / p >
< p > Options:< / p >
< ul >
< li > additional-versions
< ul >
< li > Search for additional versions of shared object, given
shared object “c” and additional versions “6” “7” on linux the
files “libc”, “libc.6”, “libc.7” are searched for.< / li >
< li > Can be either numbers or strings< / li >
< / ul > < / li >
< li > additional-paths
< ul >
< li > Give additional paths to search shared objects from< / li >
< / ul > < / li >
< / ul >
< p > Example:< / p >
< pre > < code > (cond-expand
(windows (define-c-library libc-stdlib
' (" stdlib.h" )
" ucrtbase"
' ((additional-versions (" 0" " 6" ))
(additiona-paths (" ." )))))
(else (define-c-library libc-stdlib
(list " stdlib.h" )
" c"
' ((additional-versions (" 0" " 6" ))
(additiona-paths (" ." ))))))< / code > < / pre >
< h4 id = "notes" > Notes< / h4 >
< ul >
< li > Do not cond-expand inside the arguments, that might lead to
problems on some implementations.< / li >
< li > Do not store options in variables, that might lead to
problems on some implementations.< / li >
< li > Pass the headers using quote
< ul >
< li > As ’ < / li >
< / ul > < / li >
< li > Pass the options using quote
< ul >
< li > As ’ < / li >
< / ul > < / li >
< / ul >
< p > (< strong > define-c-procedure< / strong > < em > scheme-name< / em >
< em > shared-object< / em > < em > c-name< / em > < em > return-type< / em >
< em > argument-type< / em > )< / p >
< p > Takes a scheme-name to bind the C procedure to, shared-object
where the function is looked from, c-name of the function as
symbol, return-type and argument-types.< / p >
< p > Defines a new foreign function to be used from Scheme
code.< / p >
< p > Example:< / p >
< pre > < code > (cond-expand
(windows (define-c-library libc-stdlib ' (" stdlib.h" ) " ucrtbase" ' ()))
(else (define-c-library libc-stdlib ' (" stdlib.h" ) " c" ' (" 6" ))))
(define-c-procedure c-puts libc-stdlib ' puts ' int ' (pointer))
(c-puts " Message brought to you by foreign-c!" )< / code > < / pre >
< h4 id = "notes-1" > Notes< / h4 >
< ul >
< li > Pass the return-types using quote
< ul >
< li > As ’ < / li >
< / ul > < / li >
< / ul >
< p > (< strong > c-bytevector?< / strong > < em > obj< / em > )< / p >
< p > Returns < strong > #t< / strong > if < em > obj< / em > is c-bytevector,
otherwise returns < strong > #f< / strong > .< / p >
< p > (< strong > c-bytevector-u8-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > byte< / em > )< / p >
< p > If K is not a valid index of c-bytevector the behaviour is
undefined.< / p >
< p > Stores the byte in element k of c-bytevector.< / p >
< p > (< strong > c-bytevector-u8-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > )< / p >
< p > If K is not a valid index of c-bytevector the behaviour is
undefined.< / p >
< p > Returns the byte at index k of c-bytevector.< / p >
< p > (< strong > c-bytevector-pointer-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > pointer< / em > )< / p >
< p > If K is not a valid index of c-bytevector the behaviour is
undefined.< / p >
< p > Stores the pointer(which is also c-bytevector) in element k
of c-bytevector.< / p >
< p > (< strong > c-bytevector-pointer-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > pointer< / em > )< / p >
< p > If K is not a valid index of c-bytevector the behaviour is
undefined.< / p >
< p > Returns the pointer(which is also c-bytevector) at index k of
c-bytevector.< / p >
< h3 id = "primitives-2" > Primitives 2< / h3 >
< p > (< strong > define-c-callback< / strong > < em > scheme-name< / em >
< em > return-type< / em > < em > argument-types< / em >
< em > procedure< / em > )< / p >
< p > Takes scheme-name to bind the Scheme procedure to,
return-type, argument-types and procedure as in place
lambda.< / p >
< p > Defines a new Sceme function to be used as callback to C
code.< / p >
< p > Example:< / p >
< pre > < code > ; Load the shared library
(cond-expand
(windows (define-c-library libc-stdlib ' (" stdlib.h" ) " ucrtbase" ' ()))
(else (define-c-library ' (" stdlib.h" ) " c" ' (" " " 6" ))))
; Define C function that takes a callback
(define-c-procedure qsort libc-stdlib ' qsort ' void ' (pointer int int callback))
; Define our callback
(define-c-callback compare
' int
' (pointer pointer)
(lambda (pointer-a pointer-b)
(let ((a (c-bytevector-sint-get pointer-a (native-endianness) 0))
(b (c-bytevector-sint-get pointer-b (native-endianness) 0)))
(cond ((> a b) 1)
((= a b) 0)
((< a b) -1)))))
; Create new array of ints to be sorted
(define array (make-c-bytevector (* (c-type-size ' int) 3)))
(c-bytevector-s32-native-set! array (* (c-type-size ' int) 0) 3)
(c-bytevector-s32-native-set! array (* (c-type-size ' int) 1) 2)
(c-bytevector-s32-native-set! array (* (c-type-size ' int) 2) 1)
(display array)
(newline)
;> (3 2 1)
; Sort the array
(qsort array 3 (c-type-size ' int) compare)
(display array)
(newline)
;> (1 2 3)< / code > < / pre >
< h3 id = "c-bytevector" > c-bytevector< / h3 >
< p > Foreign-c c-bytevector interface is copied from R6RS
bytevectors, with some added functionality for C null pointers
and manual memory management.< / p >
< p > (< strong > make-c-null< / strong > )< / p >
< p > Returns a null C pointer.< / p >
< p > (< strong > c-null?< / strong > < em > obj< / em > )< / p >
< p > Returns < strong > #t< / strong > if < em > obj< / em > is a null C
pointer, otherwise returns < strong > #f< / strong > .< / p >
< p > (< strong > c-free< / strong > < em > c-bytevector< / em > )< / p >
< p > Frees < em > c-bytevector< / em > from memory.< / p >
< p > (< strong > call-with-address-of< / strong > < em > c-bytevector< / em >
< em > thunk< / em > )< / p >
< p > Calls < em > thunk< / em > with address pointer of
< em > c-bytevector< / em > .< / p >
< p > Since the support for calling C functions taking pointer
address arguments, ones prefixrd with & in C, varies, some
additional ceremony is needed on the Scheme side.< / p >
< p > Example:< / p >
< p > Calling from C:< / p >
< pre > < code > //void func(int** i);
func(& i);< / code > < / pre >
< p > Calling from Scheme:< / p >
< pre > < code > (define cbv (make-bytevector (c-type-size ' int)))
(call-with-address-of
cbv
(lambda (address)
(func address)))
; Use cbv here< / code > < / pre >
< p > The passed c-bytevector, in example named cbv, should only be
used < strong > after< / strong > call to call-with-addres-of
ends.< / p >
< p > (< strong > bytevector-> c-bytevector< / strong >
< em > bytevector< / em > )< / p >
< p > Returns a newly allocated c-bytevector of the bytes of
< em > bytevector< / em > .< / p >
< p > (< strong > c-bytevector-> bytevector< / strong > )< / p >
< p > Returns a newly allocated bytevector of the bytes of
< em > c-bytevector< / em > .< / p >
< p > (< strong > native-endianness< / strong > )< / p >
< p > Returns the endianness symbol associated implementation’
preferred endianness (usually that of the underlying machine
architecture). This may be any < endianness symbol> ,
including a symbol other than big and little.< / p >
< p > (< strong > make-c-bytevector< / strong > < em > k< / em > )< / br >
(< strong > make-c-bytevector< / strong > < em > k< / em >
< em > fill< / em > )< / p >
< p > Returns a newly allocated c-bytevector of < em > k< / em >
bytes.< / p >
< p > If the < em > fill< / em > argument is missing, the initial
contents of the returned c-bytevector are unspecified.< / p >
< p > If the < em > fill< / em > argument is present, it’
confine to C uint8_t values , it specifies the initial value for
the bytes of the c-bytevector< / p >
< p > (< strong > c-bytevector-s8-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > byte< / em > )< / p >
< p > If < em > k< / em > is not a valid index of c-bytevector the
behaviour is undefined.< / p >
< p > Stores the < em > byte< / em > in element < em > k< / em > of
< em > c-bytevector< / em > .< / p >
< p > (< strong > c-bytevector-s8-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > )< / p >
< p > If < em > k< / em > is not a valid index of c-bytevector the
behaviour is undefined.< / p >
< p > Returns the byte at index < em > k< / em > of
< em > c-bytevector< / em > .< / p >
< p > (< strong > c-bytevector-char-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > char< / em > )< / p >
< p > If < em > k< / em > is not a valid index of c-bytevector the
behaviour is undefined.< / p >
< p > Stores the < em > char< / em > in element < em > k< / em > of
< em > c-bytevector< / em > .< / p >
< p > (< strong > c-bytevector-char-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > )< / p >
< p > If < em > k< / em > is not a valid index of c-bytevector the
behaviour is undefined.< / p >
< p > Returns the char at index < em > k< / em > of
< em > c-bytevector< / em > .< / p >
< p > (< strong > c-bytevector-uchar-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > char< / em > )< / p >
< p > If < em > k< / em > is not a valid index of c-bytevector the
behaviour is undefined.< / p >
< p > Stores the unsigned < em > char< / em > in element < em > k< / em > of
< em > c-bytevector< / em > .< / p >
< p > (< strong > c-bytevector-uchar-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / p >
< p > If < em > k< / em > is not a valid index of c-bytevector the
behaviour is undefined.< / p >
< p > Returns the unsigned char at index < em > k< / em > of
< em > c-bytevector< / em > .< / p >
< p > (< strong > c-bytevector-uint-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > < em > size< / em > )< / br >
(< strong > c-bytevector-sint-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > < em > size< / em > )< / br >
(< strong > c-bytevector-uint-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > < em > size< / em > )< / br >
(< strong > c-bytevector-sint-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > < em > size< / em > )< / p >
< p > Size must be a positive exact integer object. If
< em > k< / em > ,…,< em > k< / em > + < em > size< / em > −
of c-bytevector the behavior is unspecified.< / p >
< p > The c-bytevector-uint-ref procedure retrieves the exact
integer object corresponding to the unsigned representation of
size < em > size< / em > and specified by < em > endianness< / em > at
indices < em > k< / em > ,…,< em > k< / em > + < em > size< / em > − < / p >
< p > The c-bytevector-sint-ref procedure retrieves the exact
integer object corresponding to the two’
representation of size < em > size< / em > and specified by
< em > endianness< / em > at indices < em > k< / em > ,…,< em > k< / em > +
< em > size< / em > − < em > n< / em > must
be an exact integer object in the interval
{0,…,256^< em > size< / em > − < / p >
< p > The c-bytevector-uint-set! procedure stores the unsigned
representation of size < em > size< / em > and specified by
< em > endianness< / em > into c-bytevector at indices
< em > k< / em > ,…,< em > k< / em > + size − < / p >
< p > The . . . -set! procedures return unspecified values.< / p >
< p > Examples:< / p >
< pre > < code > (define cbv (make-c-bytevector (c-type-size ' int)))
(c-bytevector-sint-set! cbv 0 100 (native-endianness) (c-type-size ' int))
(c-bytevector-sint-ref cbv 0 (native-endianness) (c-type-size ' int))
> 100< / code > < / pre >
< p > (< strong > c-bytevector-u16-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-s16-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-u16-native-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / br >
(< strong > c-bytevector-s16-native-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / br >
(< strong > c-bytevector-u16-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-s16-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-u16-native-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > n< / em > )< / br >
(< strong > c-bytevector-s16-native-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > n< / em > )< / p >
< p > < em > K< / em > must be a valid index of < em > c-bytevector< / em > ;
so must < em > k< / em > + 1. For c-bytevector-u16-set! and
c-bytevector-u16-native-set!, < em > n< / em > must be an exact
integer object in the interval {0,…,216 −
c-bytevector-s16-set! and c-bytevector-s16-native-set!,
< em > n< / em > must be an exact integer object in the interval
{− − < / p >
< p > These retrieve and set two-byte representations of numbers at
indices < em > k< / em > and < em > k< / em > + 1, according to the
endianness specified by < em > endianness< / em > . The procedures with
u16 in their names deal with the unsigned representation; those
with s16 in their names deal with the two’
representation.< / p >
< p > The procedures with native in their names employ the native
endianness, and work only at aligned indices: < em > k< / em > must be
a multiple of 2.< / p >
< p > The …-set! procedures return unspecified values.< / p >
< p > (< strong > c-bytevector-u32-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-s32-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-u32-native-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / br >
(< strong > c-bytevector-s32-native-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / br >
(< strong > c-bytevector-u32-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-s32-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-u32-native-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > n< / em > )< / br >
(< strong > c-bytevector-s32-native-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > n< / em > )< / p >
< p > < em > K< / em > ,…,< em > k< / em > + 3 must be valid indices of
bytevector. For c-bytevector-u32-set! and
bytevector-u32-native-set!, < em > n< / em > must be an exact integer
object in the interval {0,…,232 −
and bytevector-s32-native-set!, < em > n< / em > must be an exact
integer object in the interval {− − < / p >
< p > These retrieve and set four-byte representations of numbers
at indices < em > k< / em > ,…,< em > k< / em > + 3, according to the
endianness specified by < em > endianness< / em > . The procedures with
u32 in their names deal with the unsigned representation; those
with s32 with the two’ < / p >
< p > The procedures with native in their names employ the native
endianness, and work only at aligned indices: < em > k< / em > must be
a multiple of 4.< / p >
< p > The …-set! procedures return unspecified values.< / p >
< p > (< strong > c-bytevector-u64-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-s64-ref< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-u64-native-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / br >
(< strong > c-bytevector-s64-native-ref< / strong >
< em > c-bytevector< / em > < em > k< / em > )< / br >
(< strong > c-bytevector-u64-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-s64-set!< / strong > < em > c-bytevector< / em >
< em > k< / em > < em > n< / em > < em > endianness< / em > )< / br >
(< strong > c-bytevector-u64-native-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > n< / em > )< / br >
(< strong > c-bytevector-s64-native-set!< / strong >
< em > c-bytevector< / em > < em > k< / em > < em > n< / em > )< / p >
< p > < em > K< / em > ,…,< em > k< / em > + 7 must be valid indices of
< em > c-bytevector< / em > . For c-bytevector-u64-set! and
c-bytevector-u64-native-set!, < em > n< / em > must be an exact
integer object in the interval {0,…,264 −
c-bytevector-s64-set! and c-bytevector-s64-native-set!,
< em > n< / em > must be an exact integer object in the interval
{− − < / p >
< p > These retrieve and set eight-byte representations of numbers
at indices < em > k< / em > ,…,< em > k< / em > + 7, according to the
endianness specified by < em > endianness< / em > . The procedures with
u64 in their names deal with the unsigned representation; those
with s64 with the two’ < / p >
< p > The procedures with native in their names employ the native
endianness, and work only at aligned indices: < em > k< / em > must be
a multiple of 8.< / p >
< p > The …-set! procedures return unspecified values.< / p >
< p > (< strong > c-bytevector-ieee-single-native-ref< / strong > )< / br >
(< strong > c-bytevector-ieee-single-ref< / strong > )< / br > < / p >
< p > < em > K< / em > ,…,< em > k< / em > + 3 must be valid indices of
< em > c-bytevector< / em > . For c-bytevector-ieee-single-native-ref,
< em > k< / em > must be a multiple of 4.< / p >
< p > These procedures return the inexact real number object that
best represents the IEEE-754 single-precision number represented
by the four bytes beginning at index < em > k< / em > .< / p >
< p > (< strong > c-bytevector-ieee-double-native-ref< / strong > )< / br >
(< strong > c-bytevector-ieee-double-ref< / strong > )< / p >
< p > < em > K< / em > ,…,< em > k< / em > + 7 must be valid indices of
< em > c-bytevector< / em > . For c-bytevector-ieee-double-native-ref,
< em > k< / em > must be a multiple of 8.< / p >
< p > These procedures return the inexact real number object that
best represents the IEEE-754 double-precision number represented
by the eight bytes beginning at index < em > k< / em > .< / p >
< p > (< strong > c-bytevector-ieee-single-native-set!< / strong > )< / br >
(< strong > c-bytevector-ieee-single-set!< / strong > )< / p >
< p > < em > K< / em > ,…,< em > k< / em > + 3 must be valid indices of
< em > c-bytevector< / em > . For c-bytevector-ieee-single-native-set!,
< em > k< / em > must be a multiple of 4.< / p >
< p > These procedures store an IEEE-754 single-precision
representation of x into elements < em > k< / em > through < em > k< / em >
+ 3 of bytevector, and return unspecified values.< / p >
< p > (< strong > c-bytevector-ieee-double-native-set!< / strong > )< / br >
(< strong > c-bytevector-ieee-double-set!< / strong > )< / p >
< p > < em > K< / em > ,…,< em > k< / em > + 7 must be valid indices of
bytevector. For c-bytevector-ieee-double-native-set!, < em > k< / em >
must be a multiple of 8.< / p >
< p > These procedures store an IEEE-754 double-precision
representation of x into elements < em > k< / em > through < em > k< / em >
+ 7 of bytevector, andreturn unspecified values.< / p >
< p > (< strong > string-> c-utf8< / strong > < em > string< / em > )< / p >
< p > Returns a newly allocated (unless empty) c-bytevector that
contains the UTF-8 encoding of the given string.< / p >
< p > (< strong > c-utf8-> string< / strong >
< em > c-bytevector< / em > )< / p >
< p > Returns a newly allocated (unless empty) string whose
character sequence is encoded by the given c-bytevector.< / p >
< h3 id = "environment-variables" > Environment variables< / h3 >
< p > Setting environment variables like this on Windows works for
this library:< / p >
< pre > < code > set " FOREIGN_C_LOAD_PATH=C:\Program Files (x86)/foo/bar" < / code > < / pre >
< h4 id = "foreign_c__load_path" > FOREIGN_C__LOAD_PATH< / h4 >
< p > To add more paths to where foreign c looks for libraries set
FOREIGN_C_LOAD_PATH to paths separated by ; on windows, and : on
other operating systems.< / p >
< / body >
< / html >
