Writing a managed wrapper for unmanaged (C++) code - custom types/structs
- by Bobby
faacEncConfigurationPtr FAACAPI faacEncGetCurrentConfiguration(
faacEncHandle hEncoder);
I'm trying to come up with a simple wrapper for this C++ library; I've never done more than very simple p/invoke interop before - like one function call with primitive arguments.
So, given the above C++ function, for example, what should I do to deal with the return type, and parameter?
FAACAPI is defined as: #define FAACAPI __stdcall
faacEncConfigurationPtr is defined:
typedef struct faacEncConfiguration
{
int version;
char *name;
char *copyright;
unsigned int mpegVersion;
unsigned long bitRate;
unsigned int inputFormat;
int shortctl;
psymodellist_t *psymodellist;
int channel_map[64];
} faacEncConfiguration, *faacEncConfigurationPtr;
AFAIK this means that the return type of the function is a reference to this struct?
And faacEncHandle is:
typedef struct {
unsigned int numChannels;
unsigned long sampleRate;
...
SR_INFO *srInfo;
double *sampleBuff[MAX_CHANNELS];
...
double *freqBuff[MAX_CHANNELS];
double *overlapBuff[MAX_CHANNELS];
double *msSpectrum[MAX_CHANNELS];
CoderInfo coderInfo[MAX_CHANNELS];
ChannelInfo channelInfo[MAX_CHANNELS];
PsyInfo psyInfo[MAX_CHANNELS];
GlobalPsyInfo gpsyInfo;
faacEncConfiguration config;
psymodel_t *psymodel;
/* quantizer specific config */
AACQuantCfg aacquantCfg;
/* FFT Tables */
FFT_Tables fft_tables;
int bitDiff;
} faacEncStruct, *faacEncHandle;
So within that struct we see a lot of other types... hmm.
Essentially, I'm trying to figure out how to deal with these types in my managed wrapper?
Do I need to create versions of these types/structs, in C#? Something like this:
[StructLayout(LayoutKind.Sequential)]
struct faacEncConfiguration
{
uint useTns;
ulong bitRate;
...
}
If so then can the runtime automatically "map" these objects onto eachother?
And, would I have to create these "mapped" types for all the types in these return types/parameter type hierarchies, all the way down until I get to all primitives?
I know this is a broad topic, any advice on getting up-to-speed quickly on what I need to learn to make this happen would be very much appreciated! Thanks!
