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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [stdlib/] [a64l.c] - Blame information for rev 258

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1 207 jeremybenn
/*
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FUNCTION
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<<a64l>>, <<l64a>>---convert between radix-64 ASCII string and long
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INDEX
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        a64l
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INDEX
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        l64a
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ANSI_SYNOPSIS
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        #include <stdlib.h>
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        long a64l(const char *<[input]>);
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        char *l64a(long <[input]>);
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TRAD_SYNOPSIS
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        #include <stdlib.h>
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        long a64l(<[input]>)
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        const char *<[input]>;
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        char *l64a(<[input]>)
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        long <[input]>;
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DESCRIPTION
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Conversion is performed between long and radix-64 characters.  The
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<<l64a>> routine transforms up to 32 bits of input value starting from
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least significant bits to the most significant bits.  The input value
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is split up into a maximum of 5 groups of 6 bits and possibly one
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group of 2 bits (bits 31 and 30).
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Each group of 6 bits forms a value from 0--63 which is translated into
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a character as follows:
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O+
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o     0 = '.'
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o     1 = '/'
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o     2--11 = '0' to '9'
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o     12--37 = 'A' to 'Z'
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o     38--63 = 'a' to 'z'
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O-
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When the remaining bits are zero or all bits have been translated, a
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null terminator is appended to the string.  An input value of 0
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results in the empty string.
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The <<a64l>> function performs the reverse translation.  Each
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character is used to generate a 6-bit value for up to 30 bits and then
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a 2-bit value to complete a 32-bit result.  The null terminator means
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that the remaining digits are 0.  An empty input string or NULL string
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results in 0L.  An invalid string results in undefined behavior.  If
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the size of a long is greater than 32 bits, the result is sign-extended.
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RETURNS
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<<l64a>> returns a null-terminated string of 0 to 6 characters.
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<<a64l>> returns the 32-bit translated value from the input character string.
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PORTABILITY
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<<l64a>> and <<a64l>> are non-ANSI and are defined by the Single Unix Specification.
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Supporting OS subroutines required: None.
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*/
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#include <_ansi.h>
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#include <stdlib.h>
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#include <limits.h>
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long
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_DEFUN (a64l, (input),
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        const char *input)
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{
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  const char *ptr;
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  char ch;
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  int i, digit;
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  unsigned long result = 0;
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  if (input == NULL)
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    return 0;
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  ptr = input;
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  /* it easiest to go from most significant digit to least so find end of input or up
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     to 6 characters worth */
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  for (i = 0; i < 6; ++i)
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    {
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      if (*ptr)
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        ++ptr;
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    }
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  while (ptr > input)
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    {
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      ch = *(--ptr);
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#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
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      if (ch >= 'a')
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        digit = (ch - 'a') + 38;
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      else if (ch >= 'A')
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        digit = (ch - 'A') + 12;
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      else if (ch >= '0')
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        digit = (ch - '0') + 2;
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      else if (ch == '/')
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        digit = 1;
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      else
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        digit = 0;
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#else /* !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) */
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      switch (ch)
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        {
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        case '/':
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          digit = 1;
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          break;
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        case '0':
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        case '1':
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        case '2':
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        case '3':
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        case '4':
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        case '5':
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        case '6':
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        case '7':
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        case '8':
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        case '9':
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          digit = (ch - '0') + 2;
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          break;
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        case 'A':
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        case 'B':
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        case 'C':
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        case 'D':
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        case 'E':
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        case 'F':
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        case 'G':
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        case 'H':
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        case 'I':
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        case 'J':
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        case 'K':
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        case 'L':
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        case 'M':
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        case 'N':
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        case 'O':
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        case 'P':
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        case 'Q':
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        case 'R':
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        case 'S':
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        case 'T':
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        case 'U':
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        case 'V':
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        case 'W':
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        case 'X':
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        case 'Y':
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        case 'Z':
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          digit = (ch - 'A') + 12;
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          break;
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        case 'a':
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        case 'b':
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        case 'c':
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        case 'd':
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        case 'e':
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        case 'f':
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        case 'g':
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        case 'h':
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        case 'i':
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        case 'j':
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        case 'k':
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        case 'l':
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        case 'm':
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        case 'n':
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        case 'o':
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        case 'p':
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        case 'q':
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        case 'r':
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        case 's':
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        case 't':
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        case 'u':
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        case 'v':
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        case 'w':
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        case 'x':
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        case 'y':
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        case 'z':
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          digit = (ch - 'a') + 38;
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          break;
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        default:
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          digit = 0;
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          break;
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        }
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#endif /* !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) */ 
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      result = (result << 6) + digit;
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    }
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#if LONG_MAX > 2147483647
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  /* for implementations where long is > 32 bits, the result must be sign-extended */
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  if (result & 0x80000000)
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      return (((long)-1 >> 32) << 32) + result;
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#endif
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  return result;
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}
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