Find First Set. Used in Linux programming as a quick way to find which is the first bit of a word, starting from the least significant bit, that is set.
From the Linux kernel arch/x86/kernel/cpu/mtrr/generic.c:
high_width = ffs(size_or_mask & 0xffffffffUL) - 1;
high_width becomes the bit position of the least significant bit set in size_or_mask. Note, the least significant bit for ffs is 1, not 0, because 0 is returned if no bit is set. The -1 is used to convert the result of ffs() to the standard bit numbering.
high_width = ffs(size_or_mask & 0xffffffffUL) - 1;
high_width becomes the bit position of the least significant bit set in size_or_mask. Note, the least significant bit for ffs is 1, not 0, because 0 is returned if no bit is set. The -1 is used to convert the result of ffs() to the standard bit numbering.
by Linux nerd June 12, 2011
Get the ffsmug. "ff" is a term used to define what kind of porn you're going to find in the link it gives you. "ff" refers to female on female action. get ready for the lesbians!
by lemonlime December 7, 2004
Get the ffmug. by SpaghettiBetty August 8, 2019
Get the FFSmug. 
Fat Fuck Syndrome. A person with type-2 diabetes caused by their obesity and poor health habits. Origin guy with type-1 and friend.
by GAMECOCK-type1 June 11, 2012
Get the FFSmug.