Is there any convenient CopyMemory function in Phobos?

[Jonathan M Davis]

On 2011-06-13 16:27, Andrej Mitrovic wrote:
> Apparently in the Windows API there's a whole lot of byte-copying going
> around.
> 
> Here's an example:
> 
> int CALLBACK EnhMetaFileProc (HDC hdc, HANDLETABLE * pHandleTable,
> CONST ENHMETARECORD * pEmfRecord,
> int iHandles, LPARAM pData)
> {
> ENHMETARECORD * pEmfr ;
> 
> pEmfr = (ENHMETARECORD *) malloc (pEmfRecord->nSize) ;
> 
> CopyMemory (pEmfr, pEmfRecord, pEmfRecord->nSize) ;
> 
> if (pEmfr->iType == EMR_RECTANGLE)
> pEmfr->iType = EMR_ELLIPSE ;
> 
> PlayEnhMetaFileRecord (hdc, pHandleTable, pEmfr, iHandles) ;
> 
> free (pEmfr) ;
> 
> return TRUE ;
> }
> 
> The nSize field specifies the byte size of the structure pointed to by
> pEmfRecord. The reason copying is required is because of this code:
> if (pEmfr->iType == EMR_RECTANGLE)
> pEmfr->iType = EMR_ELLIPSE ;
> 
> pEmfRecord itself is const, so new memory has to be allocated first
> and then the memory from pEmfRecord is copied there, and then the
> iType field is changed. A simple pointer dereference won't copy all
> the bytes, since this is one of those variable-length structure types
> you often see in C code.
> 
> In D I've used the slice trick to assign a byte range of data from one
> memory location to another:
> extern (Windows)
> int EnhMetaFileProc(HDC hdc, HANDLETABLE* pHandleTable,
> const ENHMETARECORD* pEmfRecord,
> int iHandles, LPARAM pData)
> {
> ENHMETARECORD* pEmfr;
> immutable newlength = pEmfRecord.nSize;
> 
> pEmfr = cast(ENHMETARECORD*)GC.malloc(newlength);
> 
> (cast(ubyte*)pEmfr)[0..newlength] =
> (cast(ubyte*)pEmfRecord)[0..newlength];
> 
> if (pEmfr.iType == EMR_RECTANGLE)
> pEmfr.iType = EMR_ELLIPSE;
> 
> PlayEnhMetaFileRecord(hdc, pHandleTable, pEmfr, iHandles);
> 
> GC.free(pEmfr);
> return TRUE;
> }
> 
> That's quite ugly.. Is there a Phobos/Druntime and maybe
> platform-independent function that can do byte-memory copies in a
> simple way? Something like this is what I need:
> CopyBytes(dest, src, bytecount);
> 
> Btw, CopyMemory is a WinAPI specific function, but I can't even link
> to it (it's actually an alias to RtlCopyMemory, but it's not in
> kernel32.lib for some reason even though MSDN says it is).

mempcy? The C memory functions are all available in D.

- Jonathan M Davis