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#include <u.h>
#include <libc.h>
#define between(x,min,max) (((min-1-x) & (x-max-1))>>8)
int
enc16chr(int o)
{
int c;
c = between(o, 0, 9) & ('0'+o);
c |= between(o, 10, 15) & ('A'+(o-10));
return c;
}
int
dec16chr(int c)
{
int o;
o = between(c, '0', '9') & (1+(c-'0'));
o |= between(c, 'A', 'F') & (1+10+(c-'A'));
o |= between(c, 'a', 'f') & (1+10+(c-'a'));
return o-1;
}
int
dec16(uchar *out, int lim, char *in, int n)
{
int c, w = 0, i = 0;
uchar *start = out;
uchar *eout = out + lim;
while(n-- > 0){
c = dec16chr(*in++);
if(c < 0)
continue;
w = (w<<4) + c;
i++;
if(i == 2){
if(out + 1 > eout)
goto exhausted;
*out++ = w;
w = 0;
i = 0;
}
}
exhausted:
return out - start;
}
int
enc16(char *out, int lim, uchar *in, int n)
{
uint c;
char *eout = out + lim;
char *start = out;
while(n-- > 0){
c = *in++;
if(out + 2 >= eout)
goto exhausted;
*out++ = enc16chr(c>>4);
*out++ = enc16chr(c&15);
}
exhausted:
*out = 0;
return out - start;
}
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