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.Dd October 27, 2024
.Dt STDC_COUNT_ZEROS 9F
.Os
.Sh NAME
.Nm stdc_count_zeros ,
.Nm stdc_count_zeros_uc ,
.Nm stdc_count_zeros_us ,
.Nm stdc_count_zeros_ui ,
.Nm stdc_count_zeros_ul ,
.Nm stdc_count_zeros_ull
.Nd count zero bits
.Sh SYNOPSIS
.In sys/stdbit.h
.Ft "unsigned int"
.Fo stdc_count_zeros
.Fa "generic_value_type value"
.Fc
.Ft "unsigned int"
.Fo stdc_count_zeros_uc
.Fa "unsigned char value"
.Fc
.Ft "unsigned int"
.Fo stdc_count_zeros_us
.Fa "unsigned short value"
.Fc
.Ft "unsigned int"
.Fo stdc_count_zeros_ui
.Fa "unsigned int value"
.Fc
.Ft "unsigned int"
.Fo stdc_count_zeros_ul
.Fa "unsigned long value"
.Fc
.Ft "unsigned int"
.Fo stdc_count_zeros_ull
.Fa "unsigned long long value"
.Fc
.Sh DESCRIPTION
The
.Fn stdc_count_zeros
family of functions returns the number of zero bits present in
.Fa value .
.Pp
The
.Fn stdc_count_zeros
function is generic and will operate on all 8, 16, 32, and 64-bit
unsigned integers; however, it is only available in C23.
The other functions all operate on a specific integer type, but
otherwise behave the same and are available regardless of the C language
version.
.Pp
Note that if an unsigned integer is promoted, it will always be filled
with leading zeros, increasing the return value.
.Sh CONTEXT
These functions may be called from
.Sy user ,
.Sy kernel ,
or
.Sy interrupt
context.
.Sh RETURN VALUES
The functions in the
.Fn stdc_count_zeros
family always return the number of zero bits in
.Fa value .
These functions cannot fail.
.Sh INTERFACE STABILITY
.Sy Committed
.Sh SEE ALSO
.Xr stdc_count_zeros 3C ,
.Xr stdc_bit_ceil 9F ,
.Xr stdc_bit_floor 9F ,
.Xr stdc_bit_width 9F ,
.Xr stdc_count_ones 9F ,
.Xr stdc_first_leading_one 9F ,
.Xr stdc_first_leading_zero 9F ,
.Xr stdc_first_trailing_one 9F ,
.Xr stdc_first_trailing_zero 9F ,
.Xr stdc_has_single_bit 9F ,
.Xr stdc_leading_ones 9F ,
.Xr stdc_leading_zeros 9F ,
.Xr stdc_trailing_ones 9F ,
.Xr stdc_trailing_zeros 9F