Tribblix: manual page: stdc_leading_zeros

STDC_LEADING_ZEROS(9F) Kernel Functions for Drivers STDC_LEADING_ZEROS(9F)

NAME

stdc_leading_zeros, stdc_leading_zeros_uc, stdc_leading_zeros_us,
stdc_leading_zeros_ui, stdc_leading_zeros_ul, stdc_leading_zeros_ull -
count consecutive leading zero bits

SYNOPSIS

#include <sys/stdbit.h>

unsigned int
stdc_leading_zeros(generic_value_type value);

unsigned int
stdc_leading_zeros_uc(unsigned char value);

unsigned int
stdc_leading_zeros_us(unsigned short value);

unsigned int
stdc_leading_zeros_ui(unsigned int value);

unsigned int
stdc_leading_zeros_ul(unsigned long value);

unsigned int
stdc_leading_zeros_ull(unsigned long long value);

DESCRIPTION

The stdc_leading_zeros() family of functions counts the number of
consecutive zero bits present in value starting at the most significant
bit.

The stdc_leading_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.

Note that promoting an integer from one type to another increases the
quantity of leading zeros, thus increasing the return value.

CONTEXT

These functions may be called from user, kernel, or interrupt context.

RETURN VALUES

The functions in the stdc_leading_zeros() family always return the
number of leading zeros found in value. These functions cannot fail.

INTERFACE STABILITY