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   1 /****************************************************************************
   2 **
   3 ** Copyright (C) 2017 Intel Corporation
   4 **
   5 ** Permission is hereby granted, free of charge, to any person obtaining a copy
   6 ** of this software and associated documentation files (the "Software"), to deal
   7 ** in the Software without restriction, including without limitation the rights
   8 ** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 ** copies of the Software, and to permit persons to whom the Software is
  10 ** furnished to do so, subject to the following conditions:
  11 **
  12 ** The above copyright notice and this permission notice shall be included in
  13 ** all copies or substantial portions of the Software.
  14 **
  15 ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 ** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 ** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 ** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 ** LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 ** OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 ** THE SOFTWARE.
  22 **
  23 ****************************************************************************/
  24
  25 #ifndef CBOR_UTF8_H
  26 #define CBOR_UTF8_H
  27
  28 #include "compilersupport_p.h"
  29
  30 #include <stdint.h>
  31
  32 static inline uint32_t get_utf8(const uint8_t **buffer, const uint8_t *end)
  33 {
  34     int charsNeeded;
  35     uint32_t uc, min_uc;
  36     uint8_t b;
  37     ptrdiff_t n = end - *buffer;
  38     if (n == 0)
  39         return ~0U;
  40
  41     uc = *(*buffer)++;
  42     if (uc < 0x80) {
  43         /* single-byte UTF-8 */
  44         return uc;
  45     }
  46
  47     /* multi-byte UTF-8, decode it */
  48     if (unlikely(uc <= 0xC1))
  49         return ~0U;
  50     if (uc < 0xE0) {
  51         /* two-byte UTF-8 */
  52         charsNeeded = 2;
  53         min_uc = 0x80;
  54         uc &= 0x1f;
  55     } else if (uc < 0xF0) {
  56         /* three-byte UTF-8 */
  57         charsNeeded = 3;
  58         min_uc = 0x800;
  59         uc &= 0x0f;
  60     } else if (uc < 0xF5) {
  61         /* four-byte UTF-8 */
  62         charsNeeded = 4;
  63         min_uc = 0x10000;
  64         uc &= 0x07;
  65     } else {
  66         return ~0U;
  67     }
  68
  69     if (n < charsNeeded)
  70         return ~0U;
  71
  72     /* first continuation character */
  73     b = *(*buffer)++;
  74     if ((b & 0xc0) != 0x80)
  75         return ~0U;
  76     uc <<= 6;
  77     uc |= b & 0x3f;
  78
  79     if (charsNeeded > 2) {
  80         /* second continuation character */
  81         b = *(*buffer)++;
  82         if ((b & 0xc0) != 0x80)
  83             return ~0U;
  84         uc <<= 6;
  85         uc |= b & 0x3f;
  86
  87         if (charsNeeded > 3) {
  88             /* third continuation character */
  89             b = *(*buffer)++;
  90             if ((b & 0xc0) != 0x80)
  91                 return ~0U;
  92             uc <<= 6;
  93             uc |= b & 0x3f;
  94         }
  95     }
  96
  97     /* overlong sequence? surrogate pair? out or range? */
  98     if (uc < min_uc || uc - 0xd800U < 2048U || uc > 0x10ffff)
  99         return ~0U;
 100
 101     return uc;
 102 }
 103
 104 #endif /* CBOR_UTF8_H */