STDC_BIT_FLOOR(3)      FreeBSD Library Functions Manual      STDC_BIT_FLOOR(3)

NAME

     stdc_bit_floor - round down to the previous power of 2

SYNOPSIS

     /* -lc */
     #include <stdbit.h>

     unsigned char
     stdc_bit_floor_uc(unsigned char value);

     unsigned short
     stdc_bit_floor_us(unsigned short value);

     unsigned int
     stdc_bit_floor_ui(unsigned int value);

     unsigned long
     stdc_bit_floor_ul(unsigned long value);

     unsigned long long
     stdc_bit_floor_ull(unsigned long long value);

     typeof(value)
     stdc_bit_floor(value);

DESCRIPTION

     The stdc_bit_floor_type() family of functions rounds value down to the
     previous power of 2, where value is of type unsigned char, unsigned
     short, unsigned int, unsigned long, or unsigned long long for type being
     uc, us, ui, ul, or ull respectively.  The stdc_bit_floor(value) type-
     generic macro picks the appropriate stdc_bit_floor_type() function based
     on the type of value.

RETURN VALUES

     Returns value round down to the previous power of 2.  If value is equal
     to zero, zero is returned.

SEE ALSO

     stdbit(3), stdc_bit_ceil(3)

STANDARDS

     The stdc_bit_floor_type() family of functions and the stdc_bit_floor()
     type-generic macro conform to ISO/IEC 9899:2024 ("ISO C23").

HISTORY

     The stdc_bit_floor_type() family of functions and the stdc_bit_floor()
     type-generic macro were added in FreeBSD 15.1.

AUTHOR

     Robert Clausecker <fuz@FreeBSD.org>

FreeBSD 15.1-STABLE-HBSD       November 9, 2025              STDC_BIT_FLOOR(3)