c++ - Building my own LPARAM variable -

i want create own lparam pass win32 function getkeynametext(), (the first parameter takes lparam var).

this may seem doing things hard way, work around not having specific amounts of information & working @ bit level confusing me why want familiarise myself this.

so want put in lparam var is: - set 16-23 bits keyboard scan code: i've got scan code dont know how combine 32bit variable? - set 24th bit extended-key flag (i have no idea how yet alone how combine 32 bit variable) - set 25th bit dont care bit care - set bit 1?

so understand way binary & bits work...i think, amazing understand higher lvl concepts polymorphism not lower lvl computer hardware stuff :p

so have 32 bit(or byte?) variable, mean have 32 0's & 1's: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx or have variable xxxxxx, eg 100011(which 35), last number 2^0(so 1), 2^1(2), 2^2(4), .... 2^5(32).

so create lparam this:

dword scancode = 0x??;  // dword 32bit var, scan code 7 bits long? bit   extflag       = 1;        // there bit variable? how can find out extended-key flag also? bit   carebit       = 1;         //now combine this?  dword mylparam = scancode & extflag & carebit; // or lparam mylparam = scancode & extflag & carebit; 

i think best way use bitfields ( http://msdn.microsoft.com/en-us/library/ewwyfdbe%28v=vs.80%29.aspx )

heres structure use key state lparam:

union keystate {     lparam lparam;      struct     {         unsigned nrepeatcount : 16;         unsigned nscancode : 8;         unsigned nextended : 1;         unsigned nreserved : 4;         unsigned ncontext : 1;         unsigned nprev : 1;         unsigned ntrans : 1;     }; }; 

then implement as:

keystate keystate; // declared globally case wm_keydown: {     keystate.lparam = lparam;      // use values here, e.g:     printf("%d,%d,%d", keystate.nrepeatcount, keystate.nscancode, keystate.nextended);      return 0; }