Hi, Willy > [...] > > > > > > /* __systry2() is used to select one of two provided low level syscalls */ > > > #define __systry2(a, sys_a, sys_b) \ > > > ((NOLIBC__NR_##a != NOLIBC__NR_NOSYS) ? (sys_a) : (sys_b)) > > > > But this supposes that all of them are manually defined as you did above. > > I'd rather implement an ugly is_numeric() macro based on argument > > resolution. I've done it once in another project, I don't remember > > precisely where it is but I vaguely remember that it used to check > > that the string resolution of the argument gave a letter (when it > > does not exist) or a digit (when it does). I can look into that later > > if needed. But please avoid extra macro definitions as much as possible, > > they're a real pain to handle in the code. There's no error when one is > > missing or has a typo, it's difficult to follow them and they don't > > appear in the debugger. > > > > Yeah, your reply inspired me to look into the IS_ENABLED() from > ../include/linux/kconfig.h macro again, there was a __is_defined() there, let's > throw away the ugly sysnr.h. I thought of IS_ENABLED() was only for y/n/m > before, but it does return 0 when the macro is not defined, it uses the same > trick in syscall() to calculate the number of arguments, if the macro is not > defined, then, 0 "argument". > The above trick is only for ""#define something 1" ;-) BR, Zhangjin
