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#include <u.h>
#include <libc.h>
#define between(x,min,max) (((min-1-x) & (x-max-1))>>8)
int
enc32chr(int o)
{
int c;
c = between(o, 0, 25) & ('A'+o);
c |= between(o, 26, 31) & ('2'+(o-26));
return c;
}
int
dec32chr(int c)
{
int o;
o = between(c, 'A', 'Z') & (1+(c-'A'));
o |= between(c, 'a', 'z') & (1+(c-'a'));
o |= between(c, '2', '7') & (1+26+(c-'2'));
return o-1;
}
int
dec32x(uchar *dest, int ndest, char *src, int nsrc, int (*chr)(int))
{
uchar *start;
int i, j, u[8];
if(ndest+1 < (5*nsrc+7)/8)
return -1;
start = dest;
while(nsrc>=8){
for(i=0; i<8; i++){
j = chr(src[i]);
if(j < 0)
j = 0;
u[i] = j;
}
*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++){
j = chr(src[i]);
if(j < 0)
j = 0;
u[i] = j;
}
*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
enc32x(char *dest, int ndest, uchar *src, int nsrc, int (*chr)(int))
{
char *start;
int j;
if(ndest <= (8*nsrc+4)/5)
return -1;
start = dest;
while(nsrc>=5){
j = (0x1f & (src[0]>>3));
*dest++ = chr(j);
j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
*dest++ = chr(j);
j = (0x1f & (src[1]>>1));
*dest++ = chr(j);
j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
*dest++ = chr(j);
j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
*dest++ = chr(j);
j = (0x1f & (src[3]>>2));
*dest++ = chr(j);
j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
*dest++ = chr(j);
j = (0x1f & (src[4]));
*dest++ = chr(j);
src += 5;
nsrc -= 5;
}
if(nsrc){
j = (0x1f & (src[0]>>3));
*dest++ = chr(j);
j = (0x1c & (src[0]<<2));
if(nsrc == 1)
goto out;
j |= (0x03 & (src[1]>>6));
*dest++ = chr(j);
j = (0x1f & (src[1]>>1));
*dest++ = chr(j);
j = (0x10 & (src[1]<<4));
if(nsrc == 2)
goto out;
j |= (0x0f & (src[2]>>4));
*dest++ = chr(j);
j = (0x1e & (src[2]<<1));
if(nsrc == 3)
goto out;
j |= (0x01 & (src[3]>>7));
*dest++ = chr(j);
j = (0x1f & (src[3]>>2));
*dest++ = chr(j);
j = (0x18 & (src[3]<<3));
out:
*dest++ = chr(j);
}
*dest = 0;
return dest-start;
}
int
enc32(char *dest, int ndest, uchar *src, int nsrc)
{
return enc32x(dest, ndest, src, nsrc, enc32chr);
}
int
dec32(uchar *dest, int ndest, char *src, int nsrc)
{
return dec32x(dest, ndest, src, nsrc, dec32chr);
}
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