47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
#if !defined(lint) && defined(SCCSIDS)
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static char sccsid[] = "@(#)l64a.c 1.1 94/10/31 SMI"; /* from S5R2 1.5 */
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#endif
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/*LINTLIBRARY*/
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/*
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* convert long int to base 64 ascii
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* char set is [./0-9A-Za-z]
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* two's complement negatives are assumed,
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* but no assumptions are made about sign propagation on right shift
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*
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*/
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#include <values.h>
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#define BITSPERCHAR 6 /* to hold entire character set */
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#define BITSPERLONG (BITSPERBYTE * sizeof(long))
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#define NMAX ((BITSPERLONG + BITSPERCHAR - 1)/BITSPERCHAR)
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#define SIGN (-(1L << (BITSPERLONG - BITSPERCHAR - 1)))
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#define CHARMASK ((1 << BITSPERCHAR) - 1)
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#define WORDMASK ((1L << ((NMAX - 1) * BITSPERCHAR)) - 1)
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static char buf[NMAX + 1];
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char *
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l64a(lg)
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register long lg;
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{
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register char *s = buf;
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while (lg != 0) {
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register int c = ((int)lg & CHARMASK) + ('0' - 2);
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if (c > '9')
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c += 'A' - '9' - 1;
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if (c > 'Z')
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c += 'a' - 'Z' - 1;
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*s++ = c;
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/* fill high-order CHAR if negative */
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/* but suppress sign propagation */
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lg = ((lg < 0) ? (lg >> BITSPERCHAR) | SIGN :
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lg >> BITSPERCHAR) & WORDMASK;
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}
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*s = '\0';
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return (buf);
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}
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