The Tor Browser: gfx/graphite2/src/inc/bits.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /*  GRAPHITE2 LICENSING

     3     Copyright 2012, SIL International

     4     All rights reserved.

     6     This library is free software; you can redistribute it and/or modify

     7     it under the terms of the GNU Lesser General Public License as published

     8     by the Free Software Foundation; either version 2.1 of License, or

     9     (at your option) any later version.

    11     This program is distributed in the hope that it will be useful,

    12     but WITHOUT ANY WARRANTY; without even the implied warranty of

    13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14     Lesser General Public License for more details.

    16     You should also have received a copy of the GNU Lesser General Public

    17     License along with this library in the file named "LICENSE".

    18     If not, write to the Free Software Foundation, 51 Franklin Street,

    19     Suite 500, Boston, MA 02110-1335, USA or visit their web page on the

    20     internet at http://www.fsf.org/licenses/lgpl.html.

    22 Alternatively, the contents of this file may be used under the terms of the

    23 Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public

    24 License, as published by the Free Software Foundation, either version 2

    25 of the License or (at your option) any later version.

    26 */

    27 #pragma once

    29 namespace graphite2

    30 {

    32 template<typename T>

    33 inline unsigned int bit_set_count(T v)

    34 {

    35     v = v - ((v >> 1) & T(~T(0)/3));                           // temp

    36     v = (v & T(~T(0)/15*3)) + ((v >> 2) & T(~T(0)/15*3));      // temp

    37     v = (v + (v >> 4)) & T(~T(0)/255*15);                      // temp

    38     return (T)(v * T(~T(0)/255)) >> (sizeof(T)-1)*8;           // count

    39 }

    42 template<int S>

    43 inline unsigned long _mask_over_val(unsigned long v)

    44 {

    45     v = _mask_over_val<S/2>(v);

    46     v |= v >> S*4;

    47     return v;

    48 }

    50 template<>

    51 inline unsigned long _mask_over_val<1>(unsigned long v)

    52 {

    53     v |= v >> 1;

    54     v |= v >> 2;

    55     v |= v >> 4;

    56     return v;

    57 }

    59 template<typename T>

    60 inline T mask_over_val(T v)

    61 {

    62     return _mask_over_val<sizeof(T)>(v);

    63 }

    65 template<typename T>

    66 inline unsigned long next_highest_power2(T v)

    67 {

    68     return _mask_over_val<sizeof(T)>(v-1)+1;

    69 }

    71 template<typename T>

    72 inline unsigned int log_binary(T v)

    73 {

    74     return bit_set_count(mask_over_val(v))-1;

    75 }

    77 template<typename T>

    78 inline T has_zero(const T x)

    79 {

    80     return (x - T(~T(0)/255)) & ~x & T(~T(0)/255*128);

    81 }

    83 template<typename T>

    84 inline T zero_bytes(const T x, unsigned char n)

    85 {

    86     const T t = T(~T(0)/255*n);

    87     return T((has_zero(x^t) >> 7)*n);

    88 }

    90 }

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