sys/src/libc/port/u64.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 enum {
   5         INVAL=  255
   6 };
   7
   8 static uchar t64d[256] = {
   9    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  10    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  11    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,   62,INVAL,INVAL,INVAL,   63,
  12       52,   53,   54,   55,   56,   57,   58,   59,   60,   61,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  13    INVAL,    0,    1,    2,    3,    4,    5,    6,    7,    8,    9,   10,   11,   12,   13,   14,
  14       15,   16,   17,   18,   19,   20,   21,   22,   23,   24,   25,INVAL,INVAL,INVAL,INVAL,INVAL,
  15    INVAL,   26,   27,   28,   29,   30,   31,   32,   33,   34,   35,   36,   37,   38,   39,   40,
  16       41,   42,   43,   44,   45,   46,   47,   48,   49,   50,   51,INVAL,INVAL,INVAL,INVAL,INVAL,
  17    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  18    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  19    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  20    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  21    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  22    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  23    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
  24    INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL
  25 };
  26 static char t64e[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  27
  28 int
  29 dec64(uchar *out, int lim, char *in, int n)
  30 {
  31         ulong b24;
  32         uchar *start = out;
  33         uchar *e = out + lim;
  34         int i, c;
  35
  36         b24 = 0;
  37         i = 0;
  38         while(n-- > 0){
  39
  40                 c = t64d[*(uchar*)in++];
  41                 if(c == INVAL)
  42                         continue;
  43                 switch(i){
  44                 case 0:
  45                         b24 = c<<18;
  46                         break;
  47                 case 1:
  48                         b24 |= c<<12;
  49                         break;
  50                 case 2:
  51                         b24 |= c<<6;
  52                         break;
  53                 case 3:
  54                         if(out + 3 > e)
  55                                 goto exhausted;
  56
  57                         b24 |= c;
  58                         *out++ = b24>>16;
  59                         *out++ = b24>>8;
  60                         *out++ = b24;
  61                         i = -1;
  62                         break;
  63                 }
  64                 i++;
  65         }
  66         switch(i){
  67         case 2:
  68                 if(out + 1 > e)
  69                         goto exhausted;
  70                 *out++ = b24>>16;
  71                 break;
  72         case 3:
  73                 if(out + 2 > e)
  74                         goto exhausted;
  75                 *out++ = b24>>16;
  76                 *out++ = b24>>8;
  77                 break;
  78         }
  79 exhausted:
  80         return out - start;
  81 }
  82
  83 int
  84 enc64(char *out, int lim, uchar *in, int n)
  85 {
  86         int i;
  87         ulong b24;
  88         char *start = out;
  89         char *e = out + lim;
  90
  91         for(i = n/3; i > 0; i--){
  92                 b24 = (*in++)<<16;
  93                 b24 |= (*in++)<<8;
  94                 b24 |= *in++;
  95                 if(out + 4 >= e)
  96                         goto exhausted;
  97                 *out++ = t64e[(b24>>18)];
  98                 *out++ = t64e[(b24>>12)&0x3f];
  99                 *out++ = t64e[(b24>>6)&0x3f];
 100                 *out++ = t64e[(b24)&0x3f];
 101         }
 102
 103         switch(n%3){
 104         case 2:
 105                 b24 = (*in++)<<16;
 106                 b24 |= (*in)<<8;
 107                 if(out + 4 >= e)
 108                         goto exhausted;
 109                 *out++ = t64e[(b24>>18)];
 110                 *out++ = t64e[(b24>>12)&0x3f];
 111                 *out++ = t64e[(b24>>6)&0x3f];
 112                 *out++ = '=';
 113                 break;
 114         case 1:
 115                 b24 = (*in)<<16;
 116                 if(out + 4 >= e)
 117                         goto exhausted;
 118                 *out++ = t64e[(b24>>18)];
 119                 *out++ = t64e[(b24>>12)&0x3f];
 120                 *out++ = '=';
 121                 *out++ = '=';
 122                 break;
 123         }
 124 exhausted:
 125         *out = 0;
 126         return out - start;
 127 }