Mercurial > pub > dyncall > bindings
diff R/rdyncall/man/dynbind.Rd @ 0:0cfcc391201f
initial from svn dyncall-1745
author | Daniel Adler |
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date | Thu, 19 Mar 2015 22:26:28 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/R/rdyncall/man/dynbind.Rd Thu Mar 19 22:26:28 2015 +0100 @@ -0,0 +1,78 @@ +\name{dynbind} +\alias{dynbind} +\title{Binding C library functions via thin call wrappers} +\description{Function to bind several foreign functions of a C library via installation of thin R call wrappers.} +\usage{ +dynbind(libnames, signature, + envir=parent.frame(), callmode="default", + pat=NULL, replace=NULL, funcptr=FALSE) +} +\arguments{ + \item{libnames}{vector of character strings giving short library names of the shared library to be loaded. See \code{\link{dynfind}} for details.} + \item{signature}{character string specifying the \emph{library signature} that determines the set of foreign function names and types. See details.} + \item{envir}{the environment to use for installation of call wrappers.} + \item{callmode}{character string specifying the calling convention, see details.} + \item{pat}{NULL or regular expression character string applied to symbolic names.} + \item{replace}{NULL or replacement character string applied to \code{pat} part of symbolic names.} + \item{funcptr}{logical, that indicates whether foreign objects refer to functions (\code{FALSE}, default) or to function poiner variables (\code{TRUE} rarely needed).} +} +\details{ +\code{dynbind} makes a set of C functions available to R through installation of thin call wrappers. +The set of functions, including the symbolic name and function type, is specified by \code{signature} ; a character string that encodes a +library signature: + +The \strong{library signature} is a compact plain-text format to specify a set of function bindings. +It consists of function names and corresponding \link[=call signature]{call signatures}. Function bindings are separated +by \sQuote{;} (semicolon) ; white spaces (including tab and new line) are allowed before and after semicolon. + +\tabular{c}{ +\emph{function-name} \code{(} \emph{call-signature} \code{;} \ldots \cr +} + +Here is an example that specifies three function bindings to the OpenGL library: +\preformatted{"glAccum(If)v ; glClear(I)v ; glClearColor(ffff)v ;"} + +Symbolic names are resolved using the library specified by \code{libnames} using \code{\link{dynfind}} for loading. +For each function, a thin call wrapper function is created using the following template: + +\preformatted{ function(...) .dyncall.<MODE> ( <TARGET>, <SIGNATURE>, ... ) } + +\code{<MODE>} is replaced by \code{callmode} argument, see \code{\link{.dyncall}} for details on calling conventions. +\code{<TARGET>} is replaced by the external pointer, resolved by the \sQuote{function-name}. +\code{<SIGNATURE>} is replaced by the call signature string contained in \code{signature}. + +The call wrapper is installed in the environment given by \code{envir}. +The assignment name is obtained from the function signature. +If \code{pat} and \code{replace} is given, a text replacement is applied to the name before assignment, useful for basic C name space mangling such as exchanging the prefix. + +As a special case, \code{dynbind} supports binding of pointer-to-function variables, indicated by setting \code{funcptr} to \code{TRUE}, in which case \code{<TARGET>} +is replaced with the expression \code{.unpack(<TARGET>,"p",0)} in order to dereference \code{<TARGET>} as a pointer-to-function variable at call-time. +} + +\value{ +The function returns a list with two fields: +\item{libhandle}{External pointer returned by \code{\link{.dynload}}.} +\item{unresolved.symbols}{vector of character strings, the names of unresolved symbols.} + +As a side effect, for each wrapper, \code{dynbind} assigns the \sQuote{function-name} to the corresponding call wrapper function in the environment given by \code{envir}. + +If no shared library is found, an error is reported. +} +\examples{ +\donttest{ +# Install two wrappers to functions of the R shared C library. +info <- dynbind("R"," +R_ShowMessage(Z)v; +R_rsort(pi)v; +") +R_ShowMessage("hello") +} +} +\seealso{ +\code{\link{.dyncall}} for details on call signatures and calling conventions, +\code{\link{dynfind}} for details on short library names, +\code{\link{.unpack}} for details on reading low-level memory (e.g. dereferencing of (function) pointer variables). +} +\keyword{programming} +\keyword{interface} +