1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* 3 * The contents of this file are subject to the Mozilla Public 4 * License Version 1.1 (the "License"); you may not use this file 5 * except in compliance with the License. You may obtain a copy of 6 * the License at http://www.mozilla.org/MPL/ 7 * 8 * Software distributed under the License is distributed on an "AS 9 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or 10 * implied. See the License for the specific language governing 11 * rights and limitations under the License. 12 * 13 * The Original Code is the Netscape Portable Runtime (NSPR). 14 * 15 * The Initial Developer of the Original Code is Netscape 16 * Communications Corporation. Portions created by Netscape are 17 * Copyright (C) 1998-2000 Netscape Communications Corporation. All 18 * Rights Reserved. 19 * 20 * Contributor(s): 21 * 22 * Alternatively, the contents of this file may be used under the 23 * terms of the GNU General Public License Version 2 or later (the 24 * "GPL"), in which case the provisions of the GPL are applicable 25 * instead of those above. If you wish to allow use of your 26 * version of this file only under the terms of the GPL and not to 27 * allow others to use your version of this file under the MPL, 28 * indicate your decision by deleting the provisions above and 29 * replace them with the notice and other provisions required by 30 * the GPL. If you do not delete the provisions above, a recipient 31 * may use your version of this file under either the MPL or the 32 * GPL. 33 */ 34 35 #ifndef prbit_h___ 36 #define prbit_h___ 37 38 #include "prtypes.h" 39 PR_BEGIN_EXTERN_C 40 41 /* 42 ** A prbitmap_t is a long integer that can be used for bitmaps 43 */ 44 typedef unsigned long prbitmap_t; 45 46 #define PR_TEST_BIT(_map,_bit) \ 47 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] & (1L << ((_bit) & (PR_BITS_PER_LONG-1)))) 48 #define PR_SET_BIT(_map,_bit) \ 49 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] |= (1L << ((_bit) & (PR_BITS_PER_LONG-1)))) 50 #define PR_CLEAR_BIT(_map,_bit) \ 51 ((_map)[(_bit)>>PR_BITS_PER_LONG_LOG2] &= ~(1L << ((_bit) & (PR_BITS_PER_LONG-1)))) 52 53 /* 54 ** Compute the log of the least power of 2 greater than or equal to n 55 */ 56 NSPR_API(PRIntn) PR_CeilingLog2(PRUint32 i); 57 58 /* 59 ** Compute the log of the greatest power of 2 less than or equal to n 60 */ 61 NSPR_API(PRIntn) PR_FloorLog2(PRUint32 i); 62 63 /* 64 ** Macro version of PR_CeilingLog2: Compute the log of the least power of 65 ** 2 greater than or equal to _n. The result is returned in _log2. 66 */ 67 #define PR_CEILING_LOG2(_log2,_n) \ 68 PR_BEGIN_MACRO \ 69 PRUint32 j_ = (PRUint32)(_n); \ 70 (_log2) = 0; \ 71 if ((j_) & ((j_)-1)) \ 72 (_log2) += 1; \ 73 if ((j_) >> 16) \ 74 (_log2) += 16, (j_) >>= 16; \ 75 if ((j_) >> 8) \ 76 (_log2) += 8, (j_) >>= 8; \ 77 if ((j_) >> 4) \ 78 (_log2) += 4, (j_) >>= 4; \ 79 if ((j_) >> 2) \ 80 (_log2) += 2, (j_) >>= 2; \ 81 if ((j_) >> 1) \ 82 (_log2) += 1; \ 83 PR_END_MACRO 84 85 /* 86 ** Macro version of PR_FloorLog2: Compute the log of the greatest power of 87 ** 2 less than or equal to _n. The result is returned in _log2. 88 ** 89 ** This is equivalent to finding the highest set bit in the word. 90 */ 91 #define PR_FLOOR_LOG2(_log2,_n) \ 92 PR_BEGIN_MACRO \ 93 PRUint32 j_ = (PRUint32)(_n); \ 94 (_log2) = 0; \ 95 if ((j_) >> 16) \ 96 (_log2) += 16, (j_) >>= 16; \ 97 if ((j_) >> 8) \ 98 (_log2) += 8, (j_) >>= 8; \ 99 if ((j_) >> 4) \ 100 (_log2) += 4, (j_) >>= 4; \ 101 if ((j_) >> 2) \ 102 (_log2) += 2, (j_) >>= 2; \ 103 if ((j_) >> 1) \ 104 (_log2) += 1; \ 105 PR_END_MACRO 106 107 PR_END_EXTERN_C 108 #endif /* prbit_h___ */ 109