What is this macro doing?

[G0rdano]

In portaudio, there are data type definitions like paInt32 and paFloat32.

I was looking at the header file where these are defined:

typedef unsigned long PaSampleFormat;  
#define paFloat32        ((PaSampleFormat) 0x00000001) 
#define paInt32          ((PaSampleFormat) 0x00000002) 
#define paInt24          ((PaSampleFormat) 0x00000004) 
#define paInt16          ((PaSampleFormat) 0x00000008) 
#define paInt8           ((PaSampleFormat) 0x00000010) 
#define paUInt8          ((PaSampleFormat) 0x00000020) 
#define paCustomFormat   ((PaSampleFormat) 0x00010000) 
#define paNonInterleaved ((PaSampleFormat) 0x80000000)  

It looks just like values being cast to unsigned int, but how would this approximate different datatypes?

[Peter87]

They are not data types. They are integer constants that have one of the bits set.

#define paFloat32        ((PaSampleFormat) 0x00000001) // first bit set
#define paInt32          ((PaSampleFormat) 0x00000002) // second bit set
#define paInt24          ((PaSampleFormat) 0x00000004) // third bit set
#define paInt16          ((PaSampleFormat) 0x00000008) // fourth bit set
#define paInt8           ((PaSampleFormat) 0x00000010) // fifth bit set
#define paUInt8          ((PaSampleFormat) 0x00000020) // sixth bit set
#define paCustomFormat   ((PaSampleFormat) 0x00010000) // seventeenth bit set
#define paNonInterleaved ((PaSampleFormat) 0x80000000) // thirty-second bit set 

They are probably meant to be used with bit masks to allow multiple of them in the same value.

PaSampleFormat frmt = paInt24 | paNonInterleaved; // non-interleaved 24 bit integer format 

https://en.wikipedia.org/wiki/Mask_%28computing%29

[G0rdano]

Yes, not sure what I was thinking, you're right they are just flags that can be or'ed together passed as arguments.