I cant understand this...

[thetransltr]

Good day! Im a C++ beginner, can anybody explain to me how this 2 codes work?


#define _RGB16BIT565(r,g,b) ((b%32) + ((g%64) << 6) + ((r%32) << 11))

#define _RGB32BIT(a,r,g,b) ( + ((g) << 8) + ((r) << 16) + ( << 24))

[Bazzy]

#define _RGB16BIT565(r,g,b) is defining a macro called _RGB16BIT565 with three parameters
The second part is some mathematical trick:

1 2 3 4 5 6 7 8 9 10 11 12 13

( (b%32) + ( (g%64) << 6 ) + ( (r%32) << 11 ) )

return the remainder of the division of 'b' by 32 ( somewhat the corresponding digit in base 32 ). See http://en.wikipedia.org/wiki/Modular_arithmetic same thing shift the last value by 6 bits ( see http://en.wikipedia.org/wiki/Arithmetic_shift ) same as above same as above

[guestgulkan]

Strange though - I thought the top one should be ((g%64) << 5) not ((g%64) << 6)

[thetransltr]

Thanks for clearing that up for me. However im having problem understanding the parenthesis for example:

#define _RGB16BIT565(r,g,b) ((b%32) + ((g%64) << 6) + ((r%32) << 11))

some opening parenthesis has no closing parenthesis which i think will give error but it didn't. Hows this syntax possible? Is creating a macro different?

[Bazzy]

some opening parenthesis has no closing parenthesis

All parentheses are matched, where do you see miss-matches?

Hows this syntax possible?Is creating a macro different?

Even if it was, you can have whatever you want in a macro
eg:

#define MACROS int main (
#define ARE ){
#define BAD return 
#define DONT 0
#define USE ; }
#define THEM


MACROS ARE BAD!!!
DONT USE THEM

[thetransltr]

Thank you guys!