ref: c8b187f9db503465460d8bafa2d7a758bbcf59ca
dir: /lib9/u64.c/
#include <lib9.h> enum { INVAL= 255 }; static uchar t64d[256] = { INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, 62,INVAL,INVAL,INVAL, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL }; static char t64e[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; int dec64(uchar *out, int lim, char *in, int n) { ulong b24; uchar *start = out; uchar *e = out + lim; int i, c; b24 = 0; i = 0; while(n-- > 0){ c = t64d[*(uchar*)in++]; if(c == INVAL) continue; switch(i){ case 0: b24 = c<<18; break; case 1: b24 |= c<<12; break; case 2: b24 |= c<<6; break; case 3: if(out + 3 > e) goto exhausted; b24 |= c; *out++ = b24>>16; *out++ = b24>>8; *out++ = b24; i = -1; break; } i++; } switch(i){ case 2: if(out + 1 > e) goto exhausted; *out++ = b24>>16; break; case 3: if(out + 2 > e) goto exhausted; *out++ = b24>>16; *out++ = b24>>8; break; } exhausted: return out - start; } int enc64(char *out, int lim, uchar *in, int n) { int i; ulong b24; char *start = out; char *e = out + lim; for(i = n/3; i > 0; i--){ b24 = (*in++)<<16; b24 |= (*in++)<<8; b24 |= *in++; if(out + 4 >= e) goto exhausted; *out++ = t64e[(b24>>18)]; *out++ = t64e[(b24>>12)&0x3f]; *out++ = t64e[(b24>>6)&0x3f]; *out++ = t64e[(b24)&0x3f]; } switch(n%3){ case 2: b24 = (*in++)<<16; b24 |= (*in)<<8; if(out + 4 >= e) goto exhausted; *out++ = t64e[(b24>>18)]; *out++ = t64e[(b24>>12)&0x3f]; *out++ = t64e[(b24>>6)&0x3f]; *out++ = '='; break; case 1: b24 = (*in)<<16; if(out + 4 >= e) goto exhausted; *out++ = t64e[(b24>>18)]; *out++ = t64e[(b24>>12)&0x3f]; *out++ = '='; *out++ = '='; break; } exhausted: *out = 0; return out - start; }