// SPDX-License-Identifier: GPL-2.0/* * * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved. * */ #include <linux/types.h> #include "ntfs_fs.h" #define BITS_IN_SIZE_T (sizeof(size_t) * 8) /* * fill_mask[i] - first i bits are '1' , i = 0,1,2,3,4,5,6,7,8 * fill_mask[i] = 0xFF >> (8-i) */static const u8 fill_mask[] = { 0x00, 0x01, 0x03, 0x07, 0x0F,				0x1F, 0x3F, 0x7F, 0xFF }; /* * zero_mask[i] - first i bits are '0' , i = 0,1,2,3,4,5,6,7,8 * zero_mask[i] = 0xFF << i */static const u8 zero_mask[] = { 0xFF, 0xFE, 0xFC, 0xF8, 0xF0,				0xE0, 0xC0, 0x80, 0x00 }; /* * are_bits_clear * * Return: True if all bits [bit, bit+nbits) are zeros "0". */bool are_bits_clear(const void *lmap, size_t bit, size_t nbits){	size_t pos = bit & 7;	const u8 *map = (u8 *)lmap + (bit >> 3); 	if (pos) {		if (8 - pos >= nbits)			return !nbits || !(*map & fill_mask[pos + nbits] &					   zero_mask[pos]); 		if (*map++ & zero_mask[pos])			return false;		nbits -= 8 - pos;	} 	pos = ((size_t)map) & (sizeof(size_t) - 1);	if (pos) {		pos = sizeof(size_t) - pos;		if (nbits >= pos * 8) {			for (nbits -= pos * 8; pos; pos--, map++) {				if (*map)					return false;			}		}	} 	for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {		if (*((size_t *)map))			return false;	} 	for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {		if (*map)			return false;	} 	pos = nbits & 7;	if (pos && (*map & fill_mask[pos]))		return false; 	return true;} /* * are_bits_set * * Return: True if all bits [bit, bit+nbits) are ones "1". */bool are_bits_set(const void *lmap, size_t bit, size_t nbits){	u8 mask;	size_t pos = bit & 7;	const u8 *map = (u8 *)lmap + (bit >> 3); 	if (pos) {		if (8 - pos >= nbits) {			mask = fill_mask[pos + nbits] & zero_mask[pos];			return !nbits || (*map & mask) == mask;		} 		mask = zero_mask[pos];		if ((*map++ & mask) != mask)			return false;		nbits -= 8 - pos;	} 	pos = ((size_t)map) & (sizeof(size_t) - 1);	if (pos) {		pos = sizeof(size_t) - pos;		if (nbits >= pos * 8) {			for (nbits -= pos * 8; pos; pos--, map++) {				if (*map != 0xFF)					return false;			}		}	} 	for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {		if (*((size_t *)map) != MINUS_ONE_T)			return false;	} 	for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {		if (*map != 0xFF)			return false;	} 	pos = nbits & 7;	if (pos) {		mask = fill_mask[pos];		if ((*map & mask) != mask)			return false;	} 	return true;}