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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129// 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;}