sys/src/libc/port/u32.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 int
   5 dec32(uchar *dest, int ndest, char *src, int nsrc)
   6 {
   7         char *s, *tab;
   8         uchar *start;
   9         int i, u[8];
  10
  11         if(ndest+1 < (5*nsrc+7)/8)
  12                 return -1;
  13         start = dest;
  14         tab = "23456789abcdefghijkmnpqrstuvwxyz";
  15         while(nsrc>=8){
  16                 for(i=0; i<8; i++){
  17                         s = strchr(tab,(int)src[i]);
  18                         u[i] = s ? s-tab : 0;
  19                 }
  20                 *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
  21                 *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
  22                 *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
  23                 *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
  24                 *dest++ = ((0x7 & u[6])<<5) | u[7];
  25                 src  += 8;
  26                 nsrc -= 8;
  27         }
  28         if(nsrc > 0){
  29                 if(nsrc == 1 || nsrc == 3 || nsrc == 6)
  30                         return -1;
  31                 for(i=0; i<nsrc; i++){
  32                         s = strchr(tab,(int)src[i]);
  33                         u[i] = s ? s-tab : 0;
  34                 }
  35                 *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
  36                 if(nsrc == 2)
  37                         goto out;
  38                 *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
  39                 if(nsrc == 4)
  40                         goto out;
  41                 *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
  42                 if(nsrc == 5)
  43                         goto out;
  44                 *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
  45         }
  46 out:
  47         return dest-start;
  48 }
  49
  50 int
  51 enc32(char *dest, int ndest, uchar *src, int nsrc)
  52 {
  53         char *tab, *start;
  54         int j;
  55
  56         if(ndest <= (8*nsrc+4)/5 )
  57                 return -1;
  58         start = dest;
  59         tab = "23456789abcdefghijkmnpqrstuvwxyz";
  60         while(nsrc>=5){
  61                 j = (0x1f & (src[0]>>3));
  62                 *dest++ = tab[j];
  63                 j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
  64                 *dest++ = tab[j];
  65                 j = (0x1f & (src[1]>>1));
  66                 *dest++ = tab[j];
  67                 j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
  68                 *dest++ = tab[j];
  69                 j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
  70                 *dest++ = tab[j];
  71                 j = (0x1f & (src[3]>>2));
  72                 *dest++ = tab[j];
  73                 j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
  74                 *dest++ = tab[j];
  75                 j = (0x1f & (src[4]));
  76                 *dest++ = tab[j];
  77                 src  += 5;
  78                 nsrc -= 5;
  79         }
  80         if(nsrc){
  81                 j = (0x1f & (src[0]>>3));
  82                 *dest++ = tab[j];
  83                 j = (0x1c & (src[0]<<2));
  84                 if(nsrc == 1)
  85                         goto out;
  86                 j |= (0x03 & (src[1]>>6));
  87                 *dest++ = tab[j];
  88                 j = (0x1f & (src[1]>>1));
  89                 if(nsrc == 2)
  90                         goto out;
  91                 *dest++ = tab[j];
  92                 j = (0x10 & (src[1]<<4));
  93                 if(nsrc == 3)
  94                         goto out;
  95                 j |= (0x0f & (src[2]>>4));
  96                 *dest++ = tab[j];
  97                 j = (0x1e & (src[2]<<1));
  98                 if(nsrc == 4)
  99                         goto out;
 100                 j |= (0x01 & (src[3]>>7));
 101                 *dest++ = tab[j];
 102                 j = (0x1f & (src[3]>>2));
 103                 *dest++ = tab[j];
 104                 j = (0x18 & (src[3]<<3));
 105 out:
 106                 *dest++ = tab[j];
 107         }
 108         *dest = 0;
 109         return dest-start;
 110 }