2 * bitops.c --- Bitmap frobbing code. See bitops.h for the inlined
5 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
8 * This file may be redistributed under the terms of the GNU Library
9 * General Public License, version 2.
16 #include <sys/types.h>
22 #ifndef _EXT2_HAVE_ASM_BITOPS_
25 * For the benefit of those who are trying to port Linux to another
26 * architecture, here are some C-language equivalents. You should
27 * recode these in the native assembly language, if at all possible.
29 * C language equivalents written by Theodore Ts'o, 9/26/92.
30 * Modified by Pete A. Zaitcev 7/14/95 to be portable to big endian
31 * systems, as well as non-32 bit systems.
34 int ext2fs_set_bit(unsigned int nr,void * addr)
37 unsigned char *ADDR = (unsigned char *) addr;
40 mask = 1 << (nr & 0x07);
41 retval = mask & *ADDR;
46 int ext2fs_clear_bit(unsigned int nr, void * addr)
49 unsigned char *ADDR = (unsigned char *) addr;
52 mask = 1 << (nr & 0x07);
53 retval = mask & *ADDR;
58 int ext2fs_test_bit(unsigned int nr, const void * addr)
61 const unsigned char *ADDR = (const unsigned char *) addr;
64 mask = 1 << (nr & 0x07);
65 return (mask & *ADDR);
68 #endif /* !_EXT2_HAVE_ASM_BITOPS_ */
70 void ext2fs_warn_bitmap(errcode_t errcode, unsigned long arg,
71 const char *description)
75 com_err(0, errcode, "#%lu for %s", arg, description);
77 com_err(0, errcode, "#%lu", arg);
85 int ext2fs_set_bit64(__u64 nr, void * addr)
88 unsigned char *ADDR = (unsigned char *) addr;
91 mask = 1 << (nr & 0x07);
92 retval = mask & *ADDR;
97 int ext2fs_clear_bit64(__u64 nr, void * addr)
100 unsigned char *ADDR = (unsigned char *) addr;
103 mask = 1 << (nr & 0x07);
104 retval = mask & *ADDR;
109 int ext2fs_test_bit64(__u64 nr, const void * addr)
112 const unsigned char *ADDR = (const unsigned char *) addr;
115 mask = 1 << (nr & 0x07);
116 return (mask & *ADDR);
119 static unsigned int popcount8(unsigned int w)
121 unsigned int res = w - ((w >> 1) & 0x55);
122 res = (res & 0x33) + ((res >> 2) & 0x33);
123 return (res + (res >> 4)) & 0x0F;
126 static unsigned int popcount32(unsigned int w)
128 unsigned int res = w - ((w >> 1) & 0x55555555);
129 res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
130 res = (res + (res >> 4)) & 0x0F0F0F0F;
131 res = res + (res >> 8);
132 return (res + (res >> 16)) & 0x000000FF;
135 unsigned int ext2fs_bitcount(const void *addr, unsigned int nbytes)
137 const unsigned char *cp = addr;
139 unsigned int res = 0;
141 while (((((uintptr_t) cp) & 3) != 0) && (nbytes > 0)) {
142 res += popcount8(*cp++);
145 p = (const __u32 *) cp;
148 res += popcount32(*p++);
151 cp = (const unsigned char *) p;
154 res += popcount8(*cp++);