1*d790b16bSRobert Clausecker.\" 2*d790b16bSRobert Clausecker.\" Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org> 3*d790b16bSRobert Clausecker.\" 4*d790b16bSRobert Clausecker.\" SPDX-License-Identifier: BSD-2-Clause 5*d790b16bSRobert Clausecker.\" 6*d790b16bSRobert Clausecker.Dd November 9, 2025 7*d790b16bSRobert Clausecker.Dt STDC_BIT_FLOOR 3 8*d790b16bSRobert Clausecker.Os 9*d790b16bSRobert Clausecker.Sh NAME 10*d790b16bSRobert Clausecker.Nm stdc_bit_floor 11*d790b16bSRobert Clausecker.Nd round down to the previous power of\~2 12*d790b16bSRobert Clausecker.Sh SYNOPSIS 13*d790b16bSRobert Clausecker.Lb libc 14*d790b16bSRobert Clausecker.In stdbit.h 15*d790b16bSRobert Clausecker.Ft unsigned char 16*d790b16bSRobert Clausecker.Fn stdc_bit_floor_uc "unsigned char value" 17*d790b16bSRobert Clausecker.Ft unsigned short 18*d790b16bSRobert Clausecker.Fn stdc_bit_floor_us "unsigned short value" 19*d790b16bSRobert Clausecker.Ft unsigned int 20*d790b16bSRobert Clausecker.Fn stdc_bit_floor_ui "unsigned int value" 21*d790b16bSRobert Clausecker.Ft unsigned long 22*d790b16bSRobert Clausecker.Fn stdc_bit_floor_ul "unsigned long value" 23*d790b16bSRobert Clausecker.Ft unsigned long long 24*d790b16bSRobert Clausecker.Fn stdc_bit_floor_ull "unsigned long long value" 25*d790b16bSRobert Clausecker.Ft typeof Ns Pq Em value 26*d790b16bSRobert Clausecker.Fn stdc_bit_floor "value" 27*d790b16bSRobert Clausecker.Sh DESCRIPTION 28*d790b16bSRobert ClauseckerThe 29*d790b16bSRobert Clausecker.Nm stdc_bit_floor_ Ns Em type Ns () 30*d790b16bSRobert Clauseckerfamily of functions rounds 31*d790b16bSRobert Clausecker.Fa value 32*d790b16bSRobert Clauseckerdown to the previous power of\~2, where 33*d790b16bSRobert Clausecker.Fa value 34*d790b16bSRobert Clauseckeris of type 35*d790b16bSRobert Clausecker.Va unsigned char , 36*d790b16bSRobert Clausecker.Va unsigned short , 37*d790b16bSRobert Clausecker.Va unsigned int , 38*d790b16bSRobert Clausecker.Va unsigned long , 39*d790b16bSRobert Clauseckeror 40*d790b16bSRobert Clausecker.Va unsigned long long 41*d790b16bSRobert Clauseckerfor 42*d790b16bSRobert Clausecker.Em type 43*d790b16bSRobert Clauseckerbeing 44*d790b16bSRobert Clausecker.Sy uc , 45*d790b16bSRobert Clausecker.Sy us , 46*d790b16bSRobert Clausecker.Sy ui , 47*d790b16bSRobert Clausecker.Sy ul , 48*d790b16bSRobert Clauseckeror 49*d790b16bSRobert Clausecker.Sy ull 50*d790b16bSRobert Clauseckerrespectively. 51*d790b16bSRobert ClauseckerThe 52*d790b16bSRobert Clausecker.Fn stdc_bit_floor "value" 53*d790b16bSRobert Clauseckertype-generic macro picks the appropriate 54*d790b16bSRobert Clausecker.Nm stdc_bit_floor_ Ns Em type Ns () 55*d790b16bSRobert Clauseckerfunction based on the type of 56*d790b16bSRobert Clausecker.Fa value . 57*d790b16bSRobert Clausecker.Sh RETURN VALUES 58*d790b16bSRobert ClauseckerReturns 59*d790b16bSRobert Clausecker.Fa value 60*d790b16bSRobert Clauseckerround down to the previous power of\~2. 61*d790b16bSRobert ClauseckerIf 62*d790b16bSRobert Clausecker.Fa value 63*d790b16bSRobert Clauseckeris equal to zero, 64*d790b16bSRobert Clauseckerzero is returned. 65*d790b16bSRobert Clausecker.Sh SEE ALSO 66*d790b16bSRobert Clausecker.Xr stdbit 3 , 67*d790b16bSRobert Clausecker.Xr stdc_bit_ceil 3 68*d790b16bSRobert Clausecker.Sh STANDARDS 69*d790b16bSRobert ClauseckerThe 70*d790b16bSRobert Clausecker.Nm stdc_bit_floor_ Ns Em type Ns () 71*d790b16bSRobert Clauseckerfamily of functions and the 72*d790b16bSRobert Clausecker.Fn stdc_bit_floor 73*d790b16bSRobert Clauseckertype-generic macro conform to 74*d790b16bSRobert Clausecker.St -isoC-2023 . 75*d790b16bSRobert Clausecker.Sh HISTORY 76*d790b16bSRobert ClauseckerThe 77*d790b16bSRobert Clausecker.Nm stdc_bit_floor_ Ns Em type Ns () 78*d790b16bSRobert Clauseckerfamily of functions and the 79*d790b16bSRobert Clausecker.Fn stdc_bit_floor 80*d790b16bSRobert Clauseckertype-generic macro were added in 81*d790b16bSRobert Clausecker.Fx 15.1. 82*d790b16bSRobert Clausecker.Sh AUTHOR 83*d790b16bSRobert Clausecker.An Robert Clausecker Aq Mt fuz@FreeBSD.org 84