1.\" 2.\" This file and its contents are supplied under the terms of the 3.\" Common Development and Distribution License ("CDDL"), version 1.0. 4.\" You may only use this file in accordance with the terms of version 5.\" 1.0 of the CDDL. 6.\" 7.\" A full copy of the text of the CDDL should have accompanied this 8.\" source. A copy of the CDDL is also available via the Internet at 9.\" http://www.illumos.org/license/CDDL. 10.\" 11.\" 12.\" Copyright 2024 Oxide Computer Company 13.\" 14.Dd October 27, 2024 15.Dt STDC_TRAILING_ZEROS 9F 16.Os 17.Sh NAME 18.Nm stdc_trailing_zeros , 19.Nm stdc_trailing_zeros_uc , 20.Nm stdc_trailing_zeros_us , 21.Nm stdc_trailing_zeros_ui , 22.Nm stdc_trailing_zeros_ul , 23.Nm stdc_trailing_zeros_ull 24.Nd count consecutive trailing zero bits 25.Sh SYNOPSIS 26.In sys/stdbit.h 27.Ft "unsigned int" 28.Fo stdc_trailing_zeros 29.Fa "generic_value_type value" 30.Fc 31.Ft "unsigned int" 32.Fo stdc_trailing_zeros_uc 33.Fa "unsigned char value" 34.Fc 35.Ft "unsigned int" 36.Fo stdc_trailing_zeros_us 37.Fa "unsigned short value" 38.Fc 39.Ft "unsigned int" 40.Fo stdc_trailing_zeros_ui 41.Fa "unsigned int value" 42.Fc 43.Ft "unsigned int" 44.Fo stdc_trailing_zeros_ul 45.Fa "unsigned long value" 46.Fc 47.Ft "unsigned int" 48.Fo stdc_trailing_zeros_ull 49.Fa "unsigned long long value" 50.Fc 51.Sh DESCRIPTION 52The 53.Fn stdc_trailing_zeros 54family of functions counts the number of consecutive zero bits present in 55.Fa value 56starting at the least significant bit. 57.Pp 58The 59.Fn stdc_trailing_zeros 60function is generic and will operate on all 8, 16, 32, and 64-bit 61unsigned integers; however, it is only available in C23. 62The other functions all operate on a specific integer type, but 63otherwise behave the same and are available regardless of the C language 64version. 65.Sh CONTEXT 66These functions may be called from 67.Sy user , 68.Sy kernel , 69or 70.Sy interrupt 71context. 72.Sh RETURN VALUES 73The functions in the 74.Fn stdc_trailing_zeros 75family always return the number of trailing zeros found in 76.Fa value . 77These functions cannot fail. 78.Sh INTERFACE STABILITY 79.Sy Committed 80.Sh SEE ALSO 81.Xr stdc_trailing_zeros 3C , 82.Xr stdc_bit_ceil 9F , 83.Xr stdc_bit_floor 9F , 84.Xr stdc_bit_width 9F , 85.Xr stdc_count_ones 9F , 86.Xr stdc_count_zeros 9F , 87.Xr stdc_first_leading_one 9F , 88.Xr stdc_first_leading_zero 9F , 89.Xr stdc_first_trailing_one 9F , 90.Xr stdc_first_trailing_zero 9F , 91.Xr stdc_has_single_bit 9F , 92.Xr stdc_leading_ones 9F , 93.Xr stdc_leading_zeros 9F , 94.Xr stdc_trailing_ones 9F 95