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 "config.h" 14 #include <stdio.h> 15 #if HAVE_SYS_TYPES_H 16 #include <sys/types.h> 17 #endif 18 19 #include "ext2_fs.h" 20 #include "ext2fs.h" 21 22 #ifndef _EXT2_HAVE_ASM_BITOPS_ 23 24 /* 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 assmebly language, if at all possible. 28 * 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. 32 */ 33 34 int ext2fs_set_bit(unsigned int nr,void * addr) 35 { 36 int mask, retval; 37 unsigned char *ADDR = (unsigned char *) addr; 38 39 ADDR += nr >> 3; 40 mask = 1 << (nr & 0x07); 41 retval = mask & *ADDR; 42 *ADDR |= mask; 43 return retval; 44 } 45 46 int ext2fs_clear_bit(unsigned int nr, void * addr) 47 { 48 int mask, retval; 49 unsigned char *ADDR = (unsigned char *) addr; 50 51 ADDR += nr >> 3; 52 mask = 1 << (nr & 0x07); 53 retval = mask & *ADDR; 54 *ADDR &= ~mask; 55 return retval; 56 } 57 58 int ext2fs_test_bit(unsigned int nr, const void * addr) 59 { 60 int mask; 61 const unsigned char *ADDR = (const unsigned char *) addr; 62 63 ADDR += nr >> 3; 64 mask = 1 << (nr & 0x07); 65 return (mask & *ADDR); 66 } 67 68 #endif /* !_EXT2_HAVE_ASM_BITOPS_ */ 69 70 void ext2fs_warn_bitmap(errcode_t errcode, unsigned long arg, 71 const char *description) 72 { 73 #ifndef OMIT_COM_ERR 74 if (description) 75 com_err(0, errcode, "#%lu for %s", arg, description); 76 else 77 com_err(0, errcode, "#%lu", arg); 78 #endif 79 } 80 81 /* 82 * C-only 64 bit ops. 83 */ 84 85 int ext2fs_set_bit64(__u64 nr, void * addr) 86 { 87 int mask, retval; 88 unsigned char *ADDR = (unsigned char *) addr; 89 90 ADDR += nr >> 3; 91 mask = 1 << (nr & 0x07); 92 retval = mask & *ADDR; 93 *ADDR |= mask; 94 return retval; 95 } 96 97 int ext2fs_clear_bit64(__u64 nr, void * addr) 98 { 99 int mask, retval; 100 unsigned char *ADDR = (unsigned char *) addr; 101 102 ADDR += nr >> 3; 103 mask = 1 << (nr & 0x07); 104 retval = mask & *ADDR; 105 *ADDR &= ~mask; 106 return retval; 107 } 108 109 int ext2fs_test_bit64(__u64 nr, const void * addr) 110 { 111 int mask; 112 const unsigned char *ADDR = (const unsigned char *) addr; 113 114 ADDR += nr >> 3; 115 mask = 1 << (nr & 0x07); 116 return (mask & *ADDR); 117 } 118 119 static unsigned int popcount8(unsigned int w) 120 { 121 unsigned int res = w - ((w >> 1) & 0x55); 122 res = (res & 0x33) + ((res >> 2) & 0x33); 123 return (res + (res >> 4)) & 0x0F; 124 } 125 126 static unsigned int popcount32(unsigned int w) 127 { 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; 133 } 134 135 unsigned int ext2fs_bitcount(const void *addr, unsigned int nbytes) 136 { 137 const unsigned char *cp = addr; 138 const __u32 *p; 139 unsigned int res = 0; 140 141 while (((((uintptr_t) cp) & 3) != 0) && (nbytes > 0)) { 142 res += popcount8(*cp++); 143 nbytes--; 144 } 145 p = (const __u32 *) cp; 146 147 while (nbytes > 4) { 148 res += popcount32(*p++); 149 nbytes -= 4; 150 } 151 cp = (const unsigned char *) p; 152 153 while (nbytes > 0) { 154 res += popcount8(*cp++); 155 nbytes--; 156 } 157 return res; 158 } 159
