icuSources/layoutex/LXUtilities.cpp

   1 /*
   2  **********************************************************************
   3  *   Copyright (C) 2002-2003, International Business Machines
   4  *   Corporation and others.  All Rights Reserved.
   5  **********************************************************************
   6  */
   7
   8 #include "layout/LETypes.h"
   9 #include "LXUtilities.h"
  10
  11 U_NAMESPACE_BEGIN
  12
  13 //
  14 // Finds the high bit by binary searching
  15 // through the bits in n.
  16 //
  17 le_int8 LXUtilities::highBit(le_int32 value)
  18 {
  19     if (value <= 0) {
  20         return -32;
  21     }
  22
  23     le_int8 bit = 0;
  24
  25     if (value >= 1 << 16) {
  26         value >>= 16;
  27         bit += 16;
  28     }
  29
  30     if (value >= 1 << 8) {
  31         value >>= 8;
  32         bit += 8;
  33     }
  34
  35     if (value >= 1 << 4) {
  36         value >>= 4;
  37         bit += 4;
  38     }
  39
  40     if (value >= 1 << 2) {
  41         value >>= 2;
  42         bit += 2;
  43     }
  44
  45     if (value >= 1 << 1) {
  46         value >>= 1;
  47         bit += 1;
  48     }
  49
  50     return bit;
  51 }
  52
  53 le_int32 LXUtilities::search(le_int32 value, const le_int32 array[], le_int32 count)
  54 {
  55     le_int32 power = 1 << highBit(count);
  56     le_int32 extra = count - power;
  57     le_int32 probe = power;
  58     le_int32 index = 0;
  59
  60     if (value >= array[extra]) {
  61         index = extra;
  62     }
  63
  64     while (probe > (1 << 0)) {
  65         probe >>= 1;
  66
  67         if (value >= array[index + probe]) {
  68             index += probe;
  69         }
  70     }
  71
  72     return index;
  73 }
  74
  75 void LXUtilities::reverse(le_int32 array[], le_int32 length)
  76 {
  77     le_int32 front, back;
  78
  79     for (front = 0, back = length - 1; front < back; front += 1, back -= 1) {
  80         le_int32 swap = array[front];
  81
  82         array[front] = array[back];
  83         array[back]  = swap;
  84     }
  85 }
  86
  87 void LXUtilities::reverse(float array[], le_int32 length)
  88 {
  89     le_int32 front, back;
  90
  91     for (front = 0, back = length - 1; front < back; front += 1, back -= 1) {
  92         float swap = array[front];
  93
  94         array[front] = array[back];
  95         array[back]  = swap;
  96     }
  97 }
  98
  99 U_NAMESPACE_END