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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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}