Mercurial > pub > dyncall > bindings
comparison R/rdyncall/man/utils.Rd @ 0:0cfcc391201f
initial from svn dyncall-1745
| author | Daniel Adler |
|---|---|
| date | Thu, 19 Mar 2015 22:26:28 +0100 |
| parents | |
| children |
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| -1:000000000000 | 0:0cfcc391201f |
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| 1 \name{utils} | |
| 2 \alias{is.nullptr} | |
| 3 \alias{as.extptr} | |
| 4 \alias{is.externalptr} | |
| 5 \alias{floatraw} | |
| 6 \alias{as.floatraw} | |
| 7 \alias{floatraw2numeric} | |
| 8 \alias{ptr2str} | |
| 9 \alias{strarrayptr} | |
| 10 \alias{strptr} | |
| 11 \alias{offsetPtr} | |
| 12 \title{Utility functions for working with foreign C data types} | |
| 13 \description{Functions for low-level operations on C pointers as well as | |
| 14 helper functions and objects to handle C \code{float} arrays and strings.} | |
| 15 \usage{ | |
| 16 is.nullptr(x) | |
| 17 as.extptr(x) | |
| 18 is.externalptr(x) | |
| 19 floatraw(n) | |
| 20 as.floatraw(x) | |
| 21 floatraw2numeric(x) | |
| 22 ptr2str(x) | |
| 23 strarrayptr(x) | |
| 24 strptr(x) | |
| 25 offsetPtr(x, offset) | |
| 26 } | |
| 27 \arguments{ | |
| 28 \item{x}{an R object.} | |
| 29 \item{n}{number of elements to allocate.} | |
| 30 \item{offset}{a offset given in bytes.} | |
| 31 } | |
| 32 \details{ | |
| 33 | |
| 34 \code{is.nullptr} tests if the external pointer given by \code{x} represents a C \code{NULL} pointer. | |
| 35 | |
| 36 \code{as.extptr} returns an external pointer to the data area of atomic | |
| 37 vector given by \code{x}. The external pointer holds an additional reference | |
| 38 to the \code{x} R object to prevent it from garbage collection. | |
| 39 | |
| 40 \code{is.externalptr} tests if the object given by \code{x} is an external pointer. | |
| 41 | |
| 42 \code{floatraw} creates an array with a capacity to store \code{n} single-precision C \code{float} values. | |
| 43 The array is implemented via a \code{\link[base]{raw}} vector. | |
| 44 | |
| 45 \code{as.floatraw} coerces a numeric vector into a single-precision C \code{float} vector. | |
| 46 Values given by \code{x} are converted to C \code{float} values and stored in the R raw vector via \code{.pack}. | |
| 47 This function is useful when calling foreign functions that expeect a C \code{float} pointer via \code{\link{.dyncall}}. | |
| 48 | |
| 49 \code{floatraw2numeric} coerces a C \code{float} (raw) vector to a numeric vector. | |
| 50 | |
| 51 \code{ptr2str}, \code{strarrayptr}, \code{strptr} are currently experimental. | |
| 52 | |
| 53 \code{offsetPtr} creates a new external pointer pointing to \code{x} plus the byte \code{offset}. | |
| 54 If \code{x} is given as an external pointer, the address is increased by the \code{offset}, | |
| 55 or, if \code{x} is given as a atomic vector, the address of the data (pointing to offset zero) is taken as basis | |
| 56 and increased by the \code{offset}. | |
| 57 The returned external pointer is protected (as offered by the C function \code{R_MakeExternalPtr}) by the external pointer \code{x}. | |
| 58 } | |
| 59 \value{ | |
| 60 A logical value is returned by \code{is.nullptr} and \code{is.externalptr}. | |
| 61 \code{as.extptr} returns an external pointer value. | |
| 62 \code{floatraw} and \code{as.floatraw} return an atomic vector of type \code{raw} | |
| 63 tagged with class \code{'floatraw'}. | |
| 64 \code{floatraw2numeric} returns a \code{numeric} atomic vector. | |
| 65 } | |
| 66 \keyword{programming} | |
| 67 \keyword{interface} |