On Wed, Mar 29, 2017 at 07:57:50PM -0400, valdis.kletnieks@xxxxxx wrote: > On Thu, 30 Mar 2017 09:59:44 +1100, "Tobin C. Harding" said: > > What is the reason for the zero bit shift in this code please? > > > > #define SDIO_STATE_PRESENT (1<<0) /* present in sysfs */ > > > > file: include/linux/mmc/sdio_func.h > > Most likely, to indicate that it's a bitmask in the 'unsigned int state' > in the line above, rather than an integer. > > See the other 2 uses of the flag in-tree: > > [/usr/src/linux-next] git grep SDIO_STATE_PRESENT > include/linux/mmc/sdio_func.h:#define SDIO_STATE_PRESENT (1<<0) /* present in sysfs */ > include/linux/mmc/sdio_func.h:#define sdio_func_present(f) ((f)->state & SDIO_STATE_PRESENT) > include/linux/mmc/sdio_func.h:#define sdio_func_set_present(f) ((f)->state |= SDIO_STATE_PRESENT) > Awesome, thanks. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
