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1 /*
2  * @(#)DeviceTables.cpp 1.5 00/03/15
3  *
4  * (C) Copyright IBM Corp. 1998 - 2006 - 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 #define FORMAT_COUNT LE_ARRAY_SIZE(fieldBits)
20 
getAdjustment(le_uint16 ppem) const21 le_int16 DeviceTable::getAdjustment(le_uint16 ppem) const
22 {
23     le_uint16 start = SWAPW(startSize);
24     le_uint16 format = SWAPW(deltaFormat) - 1;
25     le_int16 result = 0;
26 
27     if (ppem >= start && ppem <= SWAPW(endSize) && format < FORMAT_COUNT) {
28         le_uint16 sizeIndex = ppem - start;
29         le_uint16 bits = fieldBits[format];
30         le_uint16 count = 16 / bits;
31         le_uint16 word = SWAPW(deltaValues[sizeIndex / count]);
32         le_uint16 fieldIndex = sizeIndex % count;
33         le_uint16 shift = 16 - (bits * (fieldIndex + 1));
34         le_uint16 field = (word >> shift) & fieldMasks[format];
35 
36         result = field;
37 
38         if ((field & fieldSignBits[format]) != 0) {
39             result |= ~ fieldMasks[format];
40         }
41     }
42 
43     return result;
44 }
45 
46 U_NAMESPACE_END
47