Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>

int
dec32(uchar *dest, int ndest, char *src, int nsrc)
{
        char *s, *tab;
        uchar *start;
        int i, u[8];

        if(ndest+1 < (5*nsrc+7)/8)
                return -1;
        start = dest;
        tab = "23456789abcdefghijkmnpqrstuvwxyz";
        while(nsrc>=8){
                for(i=0; i<8; i++){
                        s = strchr(tab,(int)src[i]);
                        u[i] = s ? s-tab : 0;
                }
                *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
                *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
                *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
                *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
                *dest++ = ((0x7 & u[6])<<5) | u[7];
                src  += 8;
                nsrc -= 8;
        }
        if(nsrc > 0){
                if(nsrc == 1 || nsrc == 3 || nsrc == 6)
                        return -1;
                for(i=0; i<nsrc; i++){
                        s = strchr(tab,(int)src[i]);
                        u[i] = s ? s-tab : 0;
                }
                *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
                if(nsrc == 2)
                        goto out;
                *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
                if(nsrc == 4)
                        goto out;
                *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
                if(nsrc == 5)
                        goto out;
                *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
        }
out:
        return dest-start;
}

int
enc32(char *dest, int ndest, uchar *src, int nsrc)
{
        char *tab, *start;
        int j;

        if(ndest <= (8*nsrc+4)/5 )
                return -1;
        start = dest;
        tab = "23456789abcdefghijkmnpqrstuvwxyz";
        while(nsrc>=5){
                j = (0x1f & (src[0]>>3));
                *dest++ = tab[j];
                j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
                *dest++ = tab[j];
                j = (0x1f & (src[1]>>1));
                *dest++ = tab[j];
                j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
                *dest++ = tab[j];
                j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
                *dest++ = tab[j];
                j = (0x1f & (src[3]>>2));
                *dest++ = tab[j];
                j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
                *dest++ = tab[j];
                j = (0x1f & (src[4]));
                *dest++ = tab[j];
                src  += 5;
                nsrc -= 5;
        }
        if(nsrc){
                j = (0x1f & (src[0]>>3));
                *dest++ = tab[j];
                j = (0x1c & (src[0]<<2));
                if(nsrc == 1)
                        goto out;
                j |= (0x03 & (src[1]>>6));
                *dest++ = tab[j];
                j = (0x1f & (src[1]>>1));
                if(nsrc == 2)
                        goto out;
                *dest++ = tab[j];
                j = (0x10 & (src[1]<<4));
                if(nsrc == 3)
                        goto out;
                j |= (0x0f & (src[2]>>4));
                *dest++ = tab[j];
                j = (0x1e & (src[2]<<1));
                if(nsrc == 4)
                        goto out;
                j |= (0x01 & (src[3]>>7));
                *dest++ = tab[j];
                j = (0x1f & (src[3]>>2));
                *dest++ = tab[j];
                j = (0x18 & (src[3]<<3));
out:
                *dest++ = tab[j];
        }
        *dest = 0;
        return dest-start;
}