4  * Copyright (C) 1996-1997  Paul H. Hargrove
11  * search/set/clear bits.
20  *  Given a block of memory, its length in bits, and a starting bit number,
21  *  determine the number of the first zero bits (in left-to-right ordering)
24  *  Returns >= 'size' if no zero bits are found in the range.
26  *  Accesses memory in 32-bit aligned chunks of 32-bits and thus
40 	curr = bitmap + (offset / 32);  in hfs_find_set_zero_bits()
41 	end = bitmap + ((size + 31) / 32);  in hfs_find_set_zero_bits()
43 	/* scan the first partial u32 for zero bits */  in hfs_find_set_zero_bits()
47 		i = offset % 32;  in hfs_find_set_zero_bits()
49 		for (; i < 32; mask >>= 1, i++) {  in hfs_find_set_zero_bits()
61 			for (i = 0; i < 32; mask >>= 1, i++) {  in hfs_find_set_zero_bits()
70 	start = (curr - bitmap) * 32 + i;  in hfs_find_set_zero_bits()
74 	len = min(size - start, len);  in hfs_find_set_zero_bits()
77 		if (++i >= 32)  in hfs_find_set_zero_bits()
80 		if (!--len || n & mask)  in hfs_find_set_zero_bits()
83 	if (!--len)  in hfs_find_set_zero_bits()
89 		if (len < 32)  in hfs_find_set_zero_bits()
92 			len = 32;  in hfs_find_set_zero_bits()
96 		len -= 32;  in hfs_find_set_zero_bits()
108 	*max = (curr - bitmap) * 32 + i - start;  in hfs_find_set_zero_bits()
116  *   Search for 'num_bits' consecutive cleared bits in the bitmap blocks of
123  *   u16 *num_bits: Pointer to the number of cleared bits
126  *   u16 *num_bits: The number of consecutive clear bits of the
130  *   The number of the first bit of the range of cleared bits which has been
135  *	the number of cleared bits to find.
148 	mutex_lock(&HFS_SB(sb)->bitmap_lock);  in hfs_vbm_search_free()
149 	bitmap = HFS_SB(sb)->bitmap;  in hfs_vbm_search_free()
151 	pos = hfs_find_set_zero_bits(bitmap, HFS_SB(sb)->fs_ablocks, goal, num_bits);  in hfs_vbm_search_free()
152 	if (pos >= HFS_SB(sb)->fs_ablocks) {  in hfs_vbm_search_free()
155 		if (pos >= HFS_SB(sb)->fs_ablocks) {  in hfs_vbm_search_free()
162 	HFS_SB(sb)->free_ablocks -= *num_bits;  in hfs_vbm_search_free()
165 	mutex_unlock(&HFS_SB(sb)->bitmap_lock);  in hfs_vbm_search_free()
174  *   Clear the requested bits in the volume bitmap of the hfs filesystem
178  *   u16 count: The number of bits
183  *   -1: One of the bits was already clear.  This is a strange
185  *   -2: One or more of the bits are out of range of the bitmap.
189  *   Starting with bit number 'start', 'count' bits in the volume bitmap
204 	/* are all of the bits in range? */  in hfs_clear_vbm_bits()
205 	if ((start + count) > HFS_SB(sb)->fs_ablocks)  in hfs_clear_vbm_bits()
206 		return -2;  in hfs_clear_vbm_bits()
208 	mutex_lock(&HFS_SB(sb)->bitmap_lock);  in hfs_clear_vbm_bits()
209 	/* bitmap is always on a 32-bit boundary */  in hfs_clear_vbm_bits()
210 	curr = HFS_SB(sb)->bitmap + (start / 32);  in hfs_clear_vbm_bits()
214 	i = start % 32;  in hfs_clear_vbm_bits()
216 		int j = 32 - i;  in hfs_clear_vbm_bits()
224 		count -= j;  in hfs_clear_vbm_bits()
228 	while (count >= 32) {  in hfs_clear_vbm_bits()
230 		count -= 32;  in hfs_clear_vbm_bits()
238 	HFS_SB(sb)->free_ablocks += len;  in hfs_clear_vbm_bits()
239 	mutex_unlock(&HFS_SB(sb)->bitmap_lock);  in hfs_clear_vbm_bits()