| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* bit search implementation |
| * |
| * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * Copyright (C) 2008 IBM Corporation |
| * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au> |
| * (Inspired by David Howell's find_next_bit implementation) |
| * |
| * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease |
| * size and improve performance, 2015. |
| */ |
| |
| #include <linux/bitops.h> |
| #include <linux/bitmap.h> |
| #include <linux/export.h> |
| #include <linux/math.h> |
| #include <linux/minmax.h> |
| #include <linux/swab.h> |
| |
| /* |
| * Common helper for find_bit() function family |
| * @FETCH: The expression that fetches and pre-processes each word of bitmap(s) |
| * @MUNGE: The expression that post-processes a word containing found bit (may be empty) |
| * @size: The bitmap size in bits |
| */ |
| #define FIND_FIRST_BIT(FETCH, MUNGE, size) \ |
| ({ \ |
| unsigned long idx, val, sz = (size); \ |
| \ |
| for (idx = 0; idx * BITS_PER_LONG < sz; idx++) { \ |
| val = (FETCH); \ |
| if (val) { \ |
| sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz); \ |
| break; \ |
| } \ |
| } \ |
| \ |
| sz; \ |
| }) |
| |
| /* |
| * Common helper for find_next_bit() function family |
| * @FETCH: The expression that fetches and pre-processes each word of bitmap(s) |
| * @MUNGE: The expression that post-processes a word containing found bit (may be empty) |
| * @size: The bitmap size in bits |
| * @start: The bitnumber to start searching at |
| */ |
| #define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \ |
| ({ \ |
| unsigned long mask, idx, tmp, sz = (size), __start = (start); \ |
| \ |
| if (unlikely(__start >= sz)) \ |
| goto out; \ |
| \ |
| mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \ |
| idx = __start / BITS_PER_LONG; \ |
| \ |
| for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \ |
| if ((idx + 1) * BITS_PER_LONG >= sz) \ |
| goto out; \ |
| idx++; \ |
| } \ |
| \ |
| sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \ |
| out: \ |
| sz; \ |
| }) |
| |
| #define FIND_NTH_BIT(FETCH, size, num) \ |
| ({ \ |
| unsigned long sz = (size), nr = (num), idx, w, tmp; \ |
| \ |
| for (idx = 0; (idx + 1) * BITS_PER_LONG <= sz; idx++) { \ |
| if (idx * BITS_PER_LONG + nr >= sz) \ |
| goto out; \ |
| \ |
| tmp = (FETCH); \ |
| w = hweight_long(tmp); \ |
| if (w > nr) \ |
| goto found; \ |
| \ |
| nr -= w; \ |
| } \ |
| \ |
| if (sz % BITS_PER_LONG) \ |
| tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz); \ |
| found: \ |
| sz = min(idx * BITS_PER_LONG + fns(tmp, nr), sz); \ |
| out: \ |
| sz; \ |
| }) |
| |
| #ifndef find_first_bit |
| /* |
| * Find the first set bit in a memory region. |
| */ |
| unsigned long _find_first_bit(const unsigned long *addr, unsigned long size) |
| { |
| return FIND_FIRST_BIT(addr[idx], /* nop */, size); |
| } |
| EXPORT_SYMBOL(_find_first_bit); |
| #endif |
| |
| #ifndef find_first_and_bit |
| /* |
| * Find the first set bit in two memory regions. |
| */ |
| unsigned long _find_first_and_bit(const unsigned long *addr1, |
| const unsigned long *addr2, |
| unsigned long size) |
| { |
| return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size); |
| } |
| EXPORT_SYMBOL(_find_first_and_bit); |
| #endif |
| |
| #ifndef find_first_zero_bit |
| /* |
| * Find the first cleared bit in a memory region. |
| */ |
| unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size) |
| { |
| return FIND_FIRST_BIT(~addr[idx], /* nop */, size); |
| } |
| EXPORT_SYMBOL(_find_first_zero_bit); |
| #endif |
| |
| #ifndef find_next_bit |
| unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start) |
| { |
| return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start); |
| } |
| EXPORT_SYMBOL(_find_next_bit); |
| #endif |
| |
| unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n) |
| { |
| return FIND_NTH_BIT(addr[idx], size, n); |
| } |
| EXPORT_SYMBOL(__find_nth_bit); |
| |
| unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2, |
| unsigned long size, unsigned long n) |
| { |
| return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n); |
| } |
| EXPORT_SYMBOL(__find_nth_and_bit); |
| |
| unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, |
| unsigned long size, unsigned long n) |
| { |
| return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n); |
| } |
| EXPORT_SYMBOL(__find_nth_andnot_bit); |
| |
| unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, |
| const unsigned long *addr2, |
| const unsigned long *addr3, |
| unsigned long size, unsigned long n) |
| { |
| return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n); |
| } |
| EXPORT_SYMBOL(__find_nth_and_andnot_bit); |
| |
| #ifndef find_next_and_bit |
| unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2, |
| unsigned long nbits, unsigned long start) |
| { |
| return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start); |
| } |
| EXPORT_SYMBOL(_find_next_and_bit); |
| #endif |
| |
| #ifndef find_next_andnot_bit |
| unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2, |
| unsigned long nbits, unsigned long start) |
| { |
| return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start); |
| } |
| EXPORT_SYMBOL(_find_next_andnot_bit); |
| #endif |
| |
| #ifndef find_next_or_bit |
| unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2, |
| unsigned long nbits, unsigned long start) |
| { |
| return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start); |
| } |
| EXPORT_SYMBOL(_find_next_or_bit); |
| #endif |
| |
| #ifndef find_next_zero_bit |
| unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits, |
| unsigned long start) |
| { |
| return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start); |
| } |
| EXPORT_SYMBOL(_find_next_zero_bit); |
| #endif |
| |
| #ifndef find_last_bit |
| unsigned long _find_last_bit(const unsigned long *addr, unsigned long size) |
| { |
| if (size) { |
| unsigned long val = BITMAP_LAST_WORD_MASK(size); |
| unsigned long idx = (size-1) / BITS_PER_LONG; |
| |
| do { |
| val &= addr[idx]; |
| if (val) |
| return idx * BITS_PER_LONG + __fls(val); |
| |
| val = ~0ul; |
| } while (idx--); |
| } |
| return size; |
| } |
| EXPORT_SYMBOL(_find_last_bit); |
| #endif |
| |
| unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr, |
| unsigned long size, unsigned long offset) |
| { |
| offset = find_next_bit(addr, size, offset); |
| if (offset == size) |
| return size; |
| |
| offset = round_down(offset, 8); |
| *clump = bitmap_get_value8(addr, offset); |
| |
| return offset; |
| } |
| EXPORT_SYMBOL(find_next_clump8); |
| |
| #ifdef __BIG_ENDIAN |
| |
| #ifndef find_first_zero_bit_le |
| /* |
| * Find the first cleared bit in an LE memory region. |
| */ |
| unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size) |
| { |
| return FIND_FIRST_BIT(~addr[idx], swab, size); |
| } |
| EXPORT_SYMBOL(_find_first_zero_bit_le); |
| |
| #endif |
| |
| #ifndef find_next_zero_bit_le |
| unsigned long _find_next_zero_bit_le(const unsigned long *addr, |
| unsigned long size, unsigned long offset) |
| { |
| return FIND_NEXT_BIT(~addr[idx], swab, size, offset); |
| } |
| EXPORT_SYMBOL(_find_next_zero_bit_le); |
| #endif |
| |
| #ifndef find_next_bit_le |
| unsigned long _find_next_bit_le(const unsigned long *addr, |
| unsigned long size, unsigned long offset) |
| { |
| return FIND_NEXT_BIT(addr[idx], swab, size, offset); |
| } |
| EXPORT_SYMBOL(_find_next_bit_le); |
| |
| #endif |
| |
| #endif /* __BIG_ENDIAN */ |