70 lines
1013 B
C
70 lines
1013 B
C
#include <u.h>
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#include <libc.h>
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#define between(x,min,max) (((min-1-x) & (x-max-1))>>8)
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int
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enc16chr(int o)
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{
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int c;
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c = between(o, 0, 9) & ('0'+o);
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c |= between(o, 10, 15) & ('A'+(o-10));
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return c;
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}
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int
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dec16chr(int c)
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{
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int o;
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o = between(c, '0', '9') & (1+(c-'0'));
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o |= between(c, 'A', 'F') & (1+10+(c-'A'));
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o |= between(c, 'a', 'f') & (1+10+(c-'a'));
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return o-1;
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}
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int
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dec16(uchar *out, int lim, char *in, int n)
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{
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int c, w = 0, i = 0;
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uchar *start = out;
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uchar *eout = out + lim;
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while(n-- > 0){
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c = dec16chr(*in++);
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if(c < 0)
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continue;
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w = (w<<4) + c;
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i++;
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if(i == 2){
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if(out + 1 > eout)
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goto exhausted;
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*out++ = w;
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w = 0;
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i = 0;
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}
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}
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exhausted:
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return out - start;
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}
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int
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enc16(char *out, int lim, uchar *in, int n)
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{
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uint c;
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char *eout = out + lim;
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char *start = out;
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while(n-- > 0){
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c = *in++;
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if(out + 2 >= eout)
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goto exhausted;
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*out++ = enc16chr(c>>4);
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*out++ = enc16chr(c&15);
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}
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exhausted:
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*out = 0;
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return out - start;
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}
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