Re: LPSTR to PBYTE
On Jan 13, 9:21 am, Michael Doubez <michael.dou...@free.fr> wrote:
On 13 jan, 09:22, "Larry" <dontmewit...@got.it> wrote:
"James Kanze" <james.ka...@gmail.com> ha scritto nel messaggionews:6a0b9734-58fa-40c1-a63a-12c71d23c04a@h9g2000yqa.googlegroups.com...
From a language standpoint, it's legal. But it ranks as
obfuscation: something done to make your code intentionally
difficult to read and to maintain.
If you need a pointer to an unsigned char: "unsigned char*".
think I own you a wider explanation on what I am dealing
with. I'm writing a class to wrap up the waveForm API,
especially the waveInxxx functions for the moment.
The API provides me with the WAVEHDR structure. This
structure defines the header used to identify a
waveform-audio buffer.
typedef struct {
LPSTR lpData;
DWORD dwBufferLength;
DWORD dwBytesRecorded;
DWORD dwUser;
DWORD dwFlags;
DWORD dwLoops;
struct wavehdr_tag* lpNext;
DWORD reserved;
} WAVEHDR;
This is C syntax.
It's probably a C interface. Most API are defined in terms of
C.
Prefer:
struct WAVEHDR {
// ...
};
Except don't define a symbol all caps (unless it's a macro).
His struct looks like the sort of thing Microsoft developed some
years back. And are now locked into. In my own code, I'd use
"struct WaveHeader", rather than the typedef, there'd be no
DWORD or LPSTR, and none of the Hungarian prefixes. If you're
interfacing to an existing interface, however... None of my
local variables would have the prefixes, but the name WAVEHDR is
pretty much imposed, and I've got a couple of DWORD as well
where I interface with Windows. (It's easier to just write
DWORD that it is to figure out what the actual type is.)
where (LPSTR)lpData is a: Long pointer to the address of the
waveform buffer.
I have not seen long pointer since windows 3.1. Are you really
going to code for that plateform ?
Modern Microsoft may not have long pointers, but it still has
LPSTR.
DWORD is basically a unsigned int; the only advantage is that
it is guaranteed to be 32 bits on 64 bit architecture. I
expect it is not what you want here.
DWORD is guaranteed to be the type the interface uses in its
structure.
[...]
As you can see I'm using memcpy to copy from LPSTR to PBYTE
using the correct amount of bytes...
Do you think I am in the right direction with that?
With using memcpy() to copy data yes. And copying to unsigned
char is guaranteed to preserve the binary layout.
And memcpy is guaranteed to copy "as if" through pointers to
unsigned char. (It takes void* as arguments, so you can pass it
a pointer to anything.)
Now, IMO the P* naming for pointers is still obfuscation.
Mine too, but some of the names may be imposed by the interface.
--
James Kanze