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#include "os.h"
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#include <mp.h>
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#include "dat.h"
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// convert a big-endian byte array (most significant byte first) to an mpint
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mpint*
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betomp(uchar *p, uint n, mpint *b)
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{
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	int m, s;
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	mpdigit x;
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	if(b == nil)
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		b = mpnew(0);
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	// dump leading zeros
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	while(*p == 0 && n > 1){
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		p++;
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		n--;
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	}
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	// get the space
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	mpbits(b, n*8);
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	b->top = DIGITS(n*8);
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	m = b->top-1;
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	// first digit might not be Dbytes long
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	s = ((n-1)*8)%Dbits;
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	x = 0;
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	for(; n > 0; n--){
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		x |= ((mpdigit)(*p++)) << s;
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		s -= 8;
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		if(s < 0){
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			b->p[m--] = x;
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			s = Dbits-8;
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			x = 0;
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		}
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	}
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	return b;
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}