63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
/* l64a - convert long to radix-64 ascii string
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*
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* Conversion is performed on at most 32-bits of input value starting
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* from least significant bits to the most significant bits.
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*
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* The routine splits the input value into groups of 6 bits for up to
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* 32 bits of input. This means that the last group may be 2 bits
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* (bits 30 and 31).
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*
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* Each group of 6 bits forms a value from 0-63 which is converted into
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* a character as follows:
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* 0 = '.'
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* 1 = '/'
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* 2-11 = '0' to '9'
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* 12-37 = 'A' to 'Z'
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* 38-63 = 'a' to 'z'
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*
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* When the remaining bits are zero or all 32 bits have been translated,
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* a nul terminator is appended to the resulting string. An input value of
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* 0 results in an empty string.
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*/
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#include <_ansi.h>
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#include <stdlib.h>
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#include <reent.h>
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static const char R64_ARRAY[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
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char *
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l64a (long value)
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{
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return _l64a_r (_REENT, value);
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}
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char *
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_l64a_r (struct _reent *rptr,
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long value)
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{
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char *ptr;
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char *result;
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int i, index;
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unsigned long tmp = (unsigned long)value & 0xffffffff;
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_REENT_CHECK_MISC(rptr);
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result = _REENT_L64A_BUF(rptr);
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ptr = result;
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for (i = 0; i < 6; ++i)
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{
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if (tmp == 0)
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{
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*ptr = '\0';
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break;
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}
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index = tmp & (64 - 1);
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*ptr++ = R64_ARRAY[index];
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tmp >>= 6;
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}
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return result;
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}
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