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//
// bitops.c
//
// Bitmap manipulation routines
//
// Copyright (C) 2002 Michael Ringgaard. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. Neither the name of the project nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
#include <bitops.h>
int find_first_zero_bit(void *bitmap, int len) {
int result;
if (!len) return 0;
__asm {
mov ebx, bitmap
mov edi, ebx
mov ecx, len
add ecx, 31
shr ecx, 5
xor edx, edx
mov eax, -1
repe scasd
je ffzb1
sub edi, 4
xor eax, [edi]
bsf edx, eax
ffzb1:
sub edi, ebx
shl edi, 3
add edx, edi
mov result, edx
}
return result;
}
int find_next_zero_bit(void *bitmap, int len, int start) {
unsigned long *p = ((unsigned long *) bitmap) + (start >> 5);
int set = 0;
int bit = start & 31;
int result;
if (start >= len) return len;
if (bit) {
unsigned long mask = ~(*p >> bit);
__asm {
mov eax, mask
bsf edx, eax
jne fnzb1
mov edx, 32
fnzb1:
mov set, edx
}
if (set < (32 - bit)) return set + start;
set = 32 - bit;
p++;
}
result = find_first_zero_bit (p, len - 32 * (p - (unsigned long *) bitmap));
return start + set + result;
}