/********************************************************************** * Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. * * All Rights Reserved. * * Reference "/usr/src/COPYRIGHT" for applicable restrictions. * **********************************************************************/ /* SCCSID: @(#)l64a.c 3.0 4/22/86 */ /* (System 5) 1.5 */ /* 3.0 SID # 1.2 */ /*LINTLIBRARY*/ /* * convert long int to base 64 ascii * char set is [./0-9A-Za-z] * two's complement negatives are assumed, * but no assumptions are made about sign propagation on right shift * */ #include <values.h> #define BITSPERCHAR 6 /* to hold entire character set */ #define BITSPERLONG (BITSPERBYTE * sizeof(long)) #define NMAX ((BITSPERLONG + BITSPERCHAR - 1)/BITSPERCHAR) #define SIGN (-(1L << (BITSPERLONG - BITSPERCHAR - 1))) #define CHARMASK ((1 << BITSPERCHAR) - 1) #define WORDMASK ((1L << ((NMAX - 1) * BITSPERCHAR)) - 1) static char buf[NMAX + 1]; char * l64a(lg) register long lg; { register char *s = buf; while (lg != 0) { register int c = ((int)lg & CHARMASK) + ('0' - 2); if (c > '9') c += 'A' - '9' - 1; if (c > 'Z') c += 'a' - 'Z' - 1; *s++ = c; /* fill high-order CHAR if negative */ /* but suppress sign propagation */ lg = ((lg < 0) ? (lg >> BITSPERCHAR) | SIGN : lg >> BITSPERCHAR) & WORDMASK; } *s = '\0'; return (buf); }