icuSources/layout/DeviceTables.cpp

   1 /*
   2  * @(#)DeviceTables.cpp 1.5 00/03/15
   3  *
   4  * (C) Copyright IBM Corp. 1998 - 2005 - All Rights Reserved
   5  *
   6  */
   7
   8 #include "LETypes.h"
   9 #include "OpenTypeTables.h"
  10 #include "DeviceTables.h"
  11 #include "LESwaps.h"
  12
  13 U_NAMESPACE_BEGIN
  14
  15 const le_uint16 DeviceTable::fieldMasks[]    = {0x0003, 0x000F, 0x00FF};
  16 const le_uint16 DeviceTable::fieldSignBits[] = {0x0002, 0x0008, 0x0080};
  17 const le_uint16 DeviceTable::fieldBits[]     = {     2,      4,      8};
  18
  19 le_int16 DeviceTable::getAdjustment(le_uint16 ppem) const
  20 {
  21     le_uint16 start = SWAPW(startSize);
  22     le_uint16 format = SWAPW(deltaFormat) - 1;
  23     le_int16 result = 0;
  24
  25     if (ppem >= start && ppem <= SWAPW(endSize)) {
  26         le_uint16 sizeIndex = ppem - start;
  27         le_uint16 bits = fieldBits[format];
  28         le_uint16 count = 16 / bits;
  29         le_uint16 word = SWAPW(deltaValues[sizeIndex / count]);
  30         le_uint16 fieldIndex = sizeIndex % count;
  31         le_uint16 shift = 16 - (bits * (fieldIndex + 1));
  32         le_uint16 field = (word >> shift) & fieldMasks[format];
  33
  34         result = field;
  35
  36         if ((field & fieldSignBits[format]) != 0) {
  37             result |= ~ fieldMasks[format];
  38         }
  39     }
  40
  41     return result;
  42 }
  43
  44 U_NAMESPACE_END