include/charset.h

   1 /*
   2  *  charset conversion utils
   3  *
   4  *  Copyright (c) 2017 Rob Clark
   5  *
   6  *  SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #ifndef __CHARSET_H_
  10 #define __CHARSET_H_
  11
  12 #include <linux/types.h>
  13
  14 #define MAX_UTF8_PER_UTF16 3
  15
  16 /**
  17  * utf16_strlen() - Get the length of an utf16 string
  18  *
  19  * Returns the number of 16 bit characters in an utf16 string, not
  20  * including the terminating NULL character.
  21  *
  22  * @in     the string to measure
  23  * @return the string length
  24  */
  25 size_t utf16_strlen(const uint16_t *in);
  26
  27 /**
  28  * utf16_strnlen() - Get the length of a fixed-size utf16 string.
  29  *
  30  * Returns the number of 16 bit characters in an utf16 string,
  31  * not including the terminating NULL character, but at most
  32  * 'count' number of characters.  In doing this, utf16_strnlen()
  33  * looks at only the first 'count' characters.
  34  *
  35  * @in     the string to measure
  36  * @count  the maximum number of characters to count
  37  * @return the string length, up to a maximum of 'count'
  38  */
  39 size_t utf16_strnlen(const uint16_t *in, size_t count);
  40
  41 /**
  42  * utf16_strcpy() - UTF16 equivalent of strcpy()
  43  */
  44 uint16_t *utf16_strcpy(uint16_t *dest, const uint16_t *src);
  45
  46 /**
  47  * utf16_strdup() - UTF16 equivalent of strdup()
  48  */
  49 uint16_t *utf16_strdup(const uint16_t *s);
  50
  51 /**
  52  * utf16_to_utf8() - Convert an utf16 string to utf8
  53  *
  54  * Converts 'size' characters of the utf16 string 'src' to utf8
  55  * written to the 'dest' buffer.
  56  *
  57  * NOTE that a single utf16 character can generate up to 3 utf8
  58  * characters.  See MAX_UTF8_PER_UTF16.
  59  *
  60  * @dest   the destination buffer to write the utf8 characters
  61  * @src    the source utf16 string
  62  * @size   the number of utf16 characters to convert
  63  * @return the pointer to the first unwritten byte in 'dest'
  64  */
  65 uint8_t *utf16_to_utf8(uint8_t *dest, const uint16_t *src, size_t size);
  66
  67 /**
  68  * utf8_to_utf16() - Convert an utf8 string to utf16
  69  *
  70  * Converts up to 'size' characters of the utf16 string 'src' to utf8
  71  * written to the 'dest' buffer. Stops at 0x00.
  72  *
  73  * @dest   the destination buffer to write the utf8 characters
  74  * @src    the source utf16 string
  75  * @size   maximum number of utf16 characters to convert
  76  * @return the pointer to the first unwritten byte in 'dest'
  77  */
  78 uint16_t *utf8_to_utf16(uint16_t *dest, const uint8_t *src, size_t size);
  79
  80 #endif /* __CHARSET_H_ */