43 lines
584 B
C
43 lines
584 B
C
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#include "os.h"
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#include <mp.h>
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#include <libsec.h>
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#include "dat.h"
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mpint*
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mprand(int bits, void (*gen)(uchar*, int), mpint *b)
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{
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int n, m;
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mpdigit mask;
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uchar *p;
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n = DIGITS(bits);
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if(b == nil)
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b = mpnew(bits);
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else
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mpbits(b, bits);
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p = malloc(n*Dbytes);
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if(p == nil)
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return nil;
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(*gen)(p, n*Dbytes);
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betomp(p, n*Dbytes, b);
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free(p);
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// make sure we don't give too many bits
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m = bits%Dbits;
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n--;
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if(m > 0){
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mask = 1;
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mask <<= m;
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mask--;
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b->p[n] &= mask;
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}
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for(; n >= 0; n--)
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if(b->p[n] != 0)
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break;
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b->top = n+1;
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b->sign = 1;
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return b;
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}
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