sys/src/libc/port/u32.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 #define between(x,min,max)      (((min-1-x) & (x-max-1))>>8)
   5
   6 int
   7 enc32chr(int o)
   8 {
   9         int c;
  10
  11         c  = between(o,  0, 25) & ('A'+o);
  12         c |= between(o, 26, 31) & ('2'+(o-26));
  13         return c;
  14 }
  15
  16 int
  17 dec32chr(int c)
  18 {
  19         int o;
  20
  21         o  = between(c, 'A', 'Z') & (1+(c-'A'));
  22         o |= between(c, 'a', 'z') & (1+(c-'a'));
  23         o |= between(c, '2', '7') & (1+26+(c-'2'));
  24         return o-1;
  25 }
  26
  27 int
  28 dec32(uchar *dest, int ndest, char *src, int nsrc)
  29 {
  30         uchar *start;
  31         int i, j, u[8];
  32
  33         if(ndest+1 < (5*nsrc+7)/8)
  34                 return -1;
  35         start = dest;
  36         while(nsrc>=8){
  37                 for(i=0; i<8; i++){
  38                         j = dec32chr(src[i]);
  39                         if(j < 0)
  40                                 j = 0;
  41                         u[i] = j;
  42                 }
  43                 *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
  44                 *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
  45                 *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
  46                 *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
  47                 *dest++ = ((0x7 & u[6])<<5) | u[7];
  48                 src  += 8;
  49                 nsrc -= 8;
  50         }
  51         if(nsrc > 0){
  52                 if(nsrc == 1 || nsrc == 3 || nsrc == 6)
  53                         return -1;
  54                 for(i=0; i<nsrc; i++){
  55                         j = dec32chr(src[i]);
  56                         if(j < 0)
  57                                 j = 0;
  58                         u[i] = j;
  59                 }
  60                 *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
  61                 if(nsrc == 2)
  62                         goto out;
  63                 *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
  64                 if(nsrc == 4)
  65                         goto out;
  66                 *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
  67                 if(nsrc == 5)
  68                         goto out;
  69                 *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
  70         }
  71 out:
  72         return dest-start;
  73 }
  74
  75 int
  76 enc32(char *dest, int ndest, uchar *src, int nsrc)
  77 {
  78         char *start;
  79         int j;
  80
  81         if(ndest <= (8*nsrc+4)/5)
  82                 return -1;
  83         start = dest;
  84         while(nsrc>=5){
  85                 j = (0x1f & (src[0]>>3));
  86                 *dest++ = enc32chr(j);
  87                 j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
  88                 *dest++ = enc32chr(j);
  89                 j = (0x1f & (src[1]>>1));
  90                 *dest++ = enc32chr(j);
  91                 j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
  92                 *dest++ = enc32chr(j);
  93                 j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
  94                 *dest++ = enc32chr(j);
  95                 j = (0x1f & (src[3]>>2));
  96                 *dest++ = enc32chr(j);
  97                 j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
  98                 *dest++ = enc32chr(j);
  99                 j = (0x1f & (src[4]));
 100                 *dest++ = enc32chr(j);
 101                 src  += 5;
 102                 nsrc -= 5;
 103         }
 104         if(nsrc){
 105                 j = (0x1f & (src[0]>>3));
 106                 *dest++ = enc32chr(j);
 107                 j = (0x1c & (src[0]<<2));
 108                 if(nsrc == 1)
 109                         goto out;
 110                 j |= (0x03 & (src[1]>>6));
 111                 *dest++ = enc32chr(j);
 112                 j = (0x1f & (src[1]>>1));
 113                 *dest++ = enc32chr(j);
 114                 j = (0x10 & (src[1]<<4));
 115                 if(nsrc == 2)
 116                         goto out;
 117                 j |= (0x0f & (src[2]>>4));
 118                 *dest++ = enc32chr(j);
 119                 j = (0x1e & (src[2]<<1));
 120                 if(nsrc == 3)
 121                         goto out;
 122                 j |= (0x01 & (src[3]>>7));
 123                 *dest++ = enc32chr(j);
 124                 j = (0x1f & (src[3]>>2));
 125                 *dest++ = enc32chr(j);
 126                 j = (0x18 & (src[3]<<3));
 127 out:
 128                 *dest++ = enc32chr(j);
 129         }
 130         *dest = 0;
 131         return dest-start;
 132 }