まともなエンジニアの作ったキー生成ルーチン

unsigned GenKey000(){ return KEY000; }
unsigned GenKey001(){ return KEY001 }
unsigned GenKey002(){ return KEY002; }
...
#define MAXCH 999
unsigned (*pGenKeyCH [MAXCH])()={GenKey000, GenKey001, GenKey002,,,,,,};

unsigned GenKey( unsigned ch )
{
if (ch >MAXCH ){
return ERR;
}
return (pGenKeyCH [ch] )();
}