common/include/hexdigit.h

   1 /* nbdkit
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  32
  33 #ifndef NBDKIT_HEXDIGIT_H
  34 #define NBDKIT_HEXDIGIT_H
  35
  36 /* Convert a hex character ('0'-'9', 'a'-'f', 'A'-'F') to the
  37  * corresponding numeric value.
  38  *
  39  * Note this does *not* check that the input is a hex character.  To
  40  * check that, see ascii_isxdigit() in ascii-ctype.h
  41  */
  42 static inline unsigned char
  43 hexdigit (const char c)
  44 {
  45   if (c >= '0' && c <= '9')
  46     return c - '0';
  47   else if (c >= 'a' && c <= 'f')
  48     return c - 'a' + 10;
  49   else /* if (c >= 'A' && c <= 'F') */
  50     return c - 'A' + 10;
  51 }
  52
  53 /* Convert a pair of hex digits x0, x1 to a byte, eg. '5', 'A' -> 0x5A */
  54 static inline unsigned char
  55 hexbyte (const char x0, const char x1)
  56 {
  57   unsigned char c0, c1;
  58
  59   c0 = hexdigit (x0);
  60   c1 = hexdigit (x1);
  61   return c0 << 4 | c1;
  62 }
  63
  64 /* Convert a number mod 16 to the corresponding hex character. */
  65 static inline const char
  66 hexchar (size_t i)
  67 {
  68   static const char hex[] = "0123456789abcdef";
  69
  70   return hex[i & 0xf];
  71 }
  72
  73 #endif /* NBDKIT_HEXDIGIT_H */