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      1 /*
      2  * Copyright 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef IMG_UTILS_TIFF_HELPERS_H
     18 #define IMG_UTILS_TIFF_HELPERS_H
     19 
     20 #include <stdint.h>
     21 
     22 namespace android {
     23 namespace img_utils {
     24 
     25 const uint8_t ZERO_WORD[] = {0, 0, 0, 0};
     26 
     27 #define BAIL_ON_FAIL(x, flag) \
     28     if ((flag = (x)) != OK) return flag;
     29 
     30 #define BYTES_TILL_WORD(index) \
     31     ((TIFF_WORD_SIZE - ((index) % TIFF_WORD_SIZE)) % TIFF_WORD_SIZE)
     32 
     33 #define WORD_ALIGN(count) \
     34     count += BYTES_TILL_WORD(count);
     35 
     36 #define ZERO_TILL_WORD(output, index, ret) \
     37     { \
     38         size_t remaining = BYTES_TILL_WORD(index); \
     39         if (remaining > 0) { \
     40             BAIL_ON_FAIL((output)->write(ZERO_WORD, 0, remaining), ret); \
     41         } \
     42     }
     43 
     44 /**
     45  * Basic TIFF header constants.
     46  */
     47 enum {
     48     BAD_OFFSET = 0,
     49     TIFF_WORD_SIZE = 4, // Size in bytes
     50     IFD_HEADER_SIZE = 2, // Size in bytes
     51     IFD_FOOTER_SIZE = 4, // Size in bytes
     52     TIFF_ENTRY_SIZE = 12, // Size in bytes
     53     MAX_IFD_ENTRIES = UINT16_MAX,
     54     FILE_HEADER_SIZE = 8, // Size in bytes
     55     ENDIAN_MARKER_SIZE = 2, // Size in bytes
     56     TIFF_MARKER_SIZE = 2, // Size in bytes
     57     OFFSET_MARKER_SIZE = 4, // Size in bytes
     58     TIFF_FILE_MARKER = 42,
     59     BIG_ENDIAN_MARKER = 0x4D4Du,
     60     LITTLE_ENDIAN_MARKER = 0x4949u
     61 };
     62 
     63 /**
     64  * Constants for the TIFF tag types.
     65  */
     66 enum TagType {
     67     UNKNOWN_TAGTYPE = 0,
     68     BYTE=1,
     69     ASCII,
     70     SHORT,
     71     LONG,
     72     RATIONAL,
     73     SBYTE,
     74     UNDEFINED,
     75     SSHORT,
     76     SLONG,
     77     SRATIONAL,
     78     FLOAT,
     79     DOUBLE
     80 };
     81 
     82 /**
     83  * Sizes of the TIFF entry fields (in bytes).
     84  */
     85 enum {
     86     TAG_SIZE = 2,
     87     TYPE_SIZE = 2,
     88     COUNT_SIZE = 4,
     89     OFFSET_SIZE = 4
     90 };
     91 
     92 /**
     93  * Convenience IFD id constants.
     94  */
     95 enum {
     96     IFD_0 = 0,
     97     RAW_IFD,
     98     PROFILE_IFD,
     99     PREVIEW_IFD
    100 };
    101 
    102 inline size_t getTypeSize(TagType type) {
    103     switch(type) {
    104         case UNDEFINED:
    105         case ASCII:
    106         case BYTE:
    107         case SBYTE:
    108             return 1;
    109         case SHORT:
    110         case SSHORT:
    111             return 2;
    112         case LONG:
    113         case SLONG:
    114         case FLOAT:
    115             return 4;
    116         case RATIONAL:
    117         case SRATIONAL:
    118         case DOUBLE:
    119             return 8;
    120         default:
    121             return 0;
    122     }
    123 }
    124 
    125 inline uint32_t calculateIfdSize(size_t numberOfEntries) {
    126     return IFD_HEADER_SIZE + IFD_FOOTER_SIZE + TIFF_ENTRY_SIZE * numberOfEntries;
    127 }
    128 
    129 } /*namespace img_utils*/
    130 } /*namespace android*/
    131 
    132 #endif /*IMG_UTILS_TIFF_HELPERS_H*/
    133