NAME

stdc_count_zeros, stdc_count_zeros_uc, stdc_count_zeros_us, stdc_count_zeros_ui, stdc_count_zeros_ul, stdc_count_zeros_ull — count zero bits

SYNOPSIS

#include <sys/stdbit.h>

unsigned int
stdc_count_zeros(generic_value_type value);

unsigned int
stdc_count_zeros_uc(unsigned char value);

unsigned int
stdc_count_zeros_us(unsigned short value);

unsigned int
stdc_count_zeros_ui(unsigned int value);

unsigned int
stdc_count_zeros_ul(unsigned long value);

unsigned int
stdc_count_zeros_ull(unsigned long long value);

DESCRIPTION

The stdc_count_zeros() family of functions returns the number of zero bits present in value.

The 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.

Note that if an unsigned integer is promoted, it will always be filled with leading zeros, increasing the return value.

CONTEXT

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

RETURN VALUES

The functions in the stdc_count_zeros() family always return the number of zero bits in value. These functions cannot fail.

INTERFACE STABILITY

Committed