1 /* 2 * bitops.c --- Bitmap frobbing code. See bitops.h for the inlined 3 * routines. 4 * 5 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o. 6 * 7 * %Begin-Header% 8 * This file may be redistributed under the terms of the GNU Library 9 * General Public License, version 2. 10 * %End-Header% 11 */ 12 13 #include <stdio.h> 14 #if HAVE_SYS_TYPES_H 15 #include <sys/types.h> 16 #endif 17 18 #include "ext2_fs.h" 19 #include "ext2fs.h" 20 21 #ifndef _EXT2_HAVE_ASM_BITOPS_ 22 23 /* 24 * For the benefit of those who are trying to port Linux to another 25 * architecture, here are some C-language equivalents. You should 26 * recode these in the native assmebly language, if at all possible. 27 * 28 * C language equivalents written by Theodore Ts'o, 9/26/92. 29 * Modified by Pete A. Zaitcev 7/14/95 to be portable to big endian 30 * systems, as well as non-32 bit systems. 31 */ 32 33 int ext2fs_set_bit(unsigned int nr,void * addr) 34 { 35 int mask, retval; 36 unsigned char *ADDR = (unsigned char *) addr; 37 38 ADDR += nr >> 3; 39 mask = 1 << (nr & 0x07); 40 retval = mask & *ADDR; 41 *ADDR |= mask; 42 return retval; 43 } 44 45 int ext2fs_clear_bit(unsigned int nr, void * addr) 46 { 47 int mask, retval; 48 unsigned char *ADDR = (unsigned char *) addr; 49 50 ADDR += nr >> 3; 51 mask = 1 << (nr & 0x07); 52 retval = mask & *ADDR; 53 *ADDR &= ~mask; 54 return retval; 55 } 56 57 int ext2fs_test_bit(unsigned int nr, const void * addr) 58 { 59 int mask; 60 const unsigned char *ADDR = (const unsigned char *) addr; 61 62 ADDR += nr >> 3; 63 mask = 1 << (nr & 0x07); 64 return (mask & *ADDR); 65 } 66 67 #endif /* !_EXT2_HAVE_ASM_BITOPS_ */ 68 69 void ext2fs_warn_bitmap(errcode_t errcode, unsigned long arg, 70 const char *description) 71 { 72 #ifndef OMIT_COM_ERR 73 if (description) 74 com_err(0, errcode, "#%lu for %s", arg, description); 75 else 76 com_err(0, errcode, "#%lu", arg); 77 #endif 78 } 79 80 /* 81 * C-only 64 bit ops. 82 */ 83 84 int ext2fs_set_bit64(__u64 nr, void * addr) 85 { 86 int mask, retval; 87 unsigned char *ADDR = (unsigned char *) addr; 88 89 ADDR += nr >> 3; 90 mask = 1 << (nr & 0x07); 91 retval = mask & *ADDR; 92 *ADDR |= mask; 93 return retval; 94 } 95 96 int ext2fs_clear_bit64(__u64 nr, void * addr) 97 { 98 int mask, retval; 99 unsigned char *ADDR = (unsigned char *) addr; 100 101 ADDR += nr >> 3; 102 mask = 1 << (nr & 0x07); 103 retval = mask & *ADDR; 104 *ADDR &= ~mask; 105 return retval; 106 } 107 108 int ext2fs_test_bit64(__u64 nr, const void * addr) 109 { 110 int mask; 111 const unsigned char *ADDR = (const unsigned char *) addr; 112 113 ADDR += nr >> 3; 114 mask = 1 << (nr & 0x07); 115 return (mask & *ADDR); 116 } 117 118 static unsigned int popcount8(unsigned int w) 119 { 120 unsigned int res = w - ((w >> 1) & 0x55); 121 res = (res & 0x33) + ((res >> 2) & 0x33); 122 return (res + (res >> 4)) & 0x0F; 123 } 124 125 static unsigned int popcount32(unsigned int w) 126 { 127 unsigned int res = w - ((w >> 1) & 0x55555555); 128 res = (res & 0x33333333) + ((res >> 2) & 0x33333333); 129 res = (res + (res >> 4)) & 0x0F0F0F0F; 130 res = res + (res >> 8); 131 return (res + (res >> 16)) & 0x000000FF; 132 } 133 134 unsigned int ext2fs_bitcount(const void *addr, unsigned int nbytes) 135 { 136 const unsigned char *cp = addr; 137 const __u32 *p; 138 unsigned int res = 0; 139 140 while (((((unsigned long) cp) & 3) != 0) && (nbytes > 0)) { 141 res += popcount8(*cp++); 142 nbytes--; 143 } 144 p = (const __u32 *) cp; 145 146 while (nbytes > 4) { 147 res += popcount32(*p++); 148 nbytes -= 4; 149 } 150 cp = (const unsigned char *) p; 151 152 while (nbytes > 0) { 153 res += popcount8(*cp++); 154 nbytes--; 155 } 156 return res; 157 } 158
