diff options
author | Yang Zhang <yang.z.zhang@intel.com> | 2015-08-28 09:58:54 +0800 |
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committer | Yang Zhang <yang.z.zhang@intel.com> | 2015-09-01 12:44:00 +0800 |
commit | e44e3482bdb4d0ebde2d8b41830ac2cdb07948fb (patch) | |
tree | 66b09f592c55df2878107a468a91d21506104d3f /qemu/util/bitops.c | |
parent | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (diff) |
Add qemu 2.4.0
Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Diffstat (limited to 'qemu/util/bitops.c')
-rw-r--r-- | qemu/util/bitops.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/qemu/util/bitops.c b/qemu/util/bitops.c new file mode 100644 index 000000000..227c38b88 --- /dev/null +++ b/qemu/util/bitops.c @@ -0,0 +1,158 @@ +/* + * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * Copyright (C) 2008 IBM Corporation + * Written by Rusty Russell <rusty@rustcorp.com.au> + * (Inspired by David Howell's find_next_bit implementation) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include "qemu/bitops.h" + +#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) + +/* + * Find the next set bit in a memory region. + */ +unsigned long find_next_bit(const unsigned long *addr, unsigned long size, + unsigned long offset) +{ + const unsigned long *p = addr + BITOP_WORD(offset); + unsigned long result = offset & ~(BITS_PER_LONG-1); + unsigned long tmp; + + if (offset >= size) { + return size; + } + size -= result; + offset %= BITS_PER_LONG; + if (offset) { + tmp = *(p++); + tmp &= (~0UL << offset); + if (size < BITS_PER_LONG) { + goto found_first; + } + if (tmp) { + goto found_middle; + } + size -= BITS_PER_LONG; + result += BITS_PER_LONG; + } + while (size >= 4*BITS_PER_LONG) { + unsigned long d1, d2, d3; + tmp = *p; + d1 = *(p+1); + d2 = *(p+2); + d3 = *(p+3); + if (tmp) { + goto found_middle; + } + if (d1 | d2 | d3) { + break; + } + p += 4; + result += 4*BITS_PER_LONG; + size -= 4*BITS_PER_LONG; + } + while (size >= BITS_PER_LONG) { + if ((tmp = *(p++))) { + goto found_middle; + } + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) { + return result; + } + tmp = *p; + +found_first: + tmp &= (~0UL >> (BITS_PER_LONG - size)); + if (tmp == 0UL) { /* Are any bits set? */ + return result + size; /* Nope. */ + } +found_middle: + return result + ctzl(tmp); +} + +/* + * This implementation of find_{first,next}_zero_bit was stolen from + * Linus' asm-alpha/bitops.h. + */ +unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size, + unsigned long offset) +{ + const unsigned long *p = addr + BITOP_WORD(offset); + unsigned long result = offset & ~(BITS_PER_LONG-1); + unsigned long tmp; + + if (offset >= size) { + return size; + } + size -= result; + offset %= BITS_PER_LONG; + if (offset) { + tmp = *(p++); + tmp |= ~0UL >> (BITS_PER_LONG - offset); + if (size < BITS_PER_LONG) { + goto found_first; + } + if (~tmp) { + goto found_middle; + } + size -= BITS_PER_LONG; + result += BITS_PER_LONG; + } + while (size & ~(BITS_PER_LONG-1)) { + if (~(tmp = *(p++))) { + goto found_middle; + } + result += BITS_PER_LONG; + size -= BITS_PER_LONG; + } + if (!size) { + return result; + } + tmp = *p; + +found_first: + tmp |= ~0UL << size; + if (tmp == ~0UL) { /* Are any bits zero? */ + return result + size; /* Nope. */ + } +found_middle: + return result + ctzl(~tmp); +} + +unsigned long find_last_bit(const unsigned long *addr, unsigned long size) +{ + unsigned long words; + unsigned long tmp; + + /* Start at final word. */ + words = size / BITS_PER_LONG; + + /* Partial final word? */ + if (size & (BITS_PER_LONG-1)) { + tmp = (addr[words] & (~0UL >> (BITS_PER_LONG + - (size & (BITS_PER_LONG-1))))); + if (tmp) { + goto found; + } + } + + while (words) { + tmp = addr[--words]; + if (tmp) { + found: + return words * BITS_PER_LONG + BITS_PER_LONG - 1 - clzl(tmp); + } + } + + /* Not found */ + return size; +} |