1 b3f61791 2004-03-21 devnull #include "os.h"
 2 b3f61791 2004-03-21 devnull #include <mp.h>
 3 b3f61791 2004-03-21 devnull #include "dat.h"
 4 b3f61791 2004-03-21 devnull 
 5 cbeb0b26 2006-04-01 devnull /* convert a big-endian byte array (most significant byte first) to an mpint */
 6 b3f61791 2004-03-21 devnull mpint*
 7 b3f61791 2004-03-21 devnull betomp(uchar *p, uint n, mpint *b)
 8 b3f61791 2004-03-21 devnull {
 9 b3f61791 2004-03-21 devnull 	int m, s;
10 b3f61791 2004-03-21 devnull 	mpdigit x;
11 b3f61791 2004-03-21 devnull 
12 b3f61791 2004-03-21 devnull 	if(b == nil)
13 b3f61791 2004-03-21 devnull 		b = mpnew(0);
14 b3f61791 2004-03-21 devnull 
15 cbeb0b26 2006-04-01 devnull 	/* dump leading zeros */
16 b3f61791 2004-03-21 devnull 	while(*p == 0 && n > 1){
17 b3f61791 2004-03-21 devnull 		p++;
18 b3f61791 2004-03-21 devnull 		n--;
19 b3f61791 2004-03-21 devnull 	}
20 b3f61791 2004-03-21 devnull 
21 cbeb0b26 2006-04-01 devnull 	/* get the space */
22 b3f61791 2004-03-21 devnull 	mpbits(b, n*8);
23 b3f61791 2004-03-21 devnull 	b->top = DIGITS(n*8);
24 b3f61791 2004-03-21 devnull 	m = b->top-1;
25 b3f61791 2004-03-21 devnull 
26 cbeb0b26 2006-04-01 devnull 	/* first digit might not be Dbytes long */
27 b3f61791 2004-03-21 devnull 	s = ((n-1)*8)%Dbits;
28 b3f61791 2004-03-21 devnull 	x = 0;
29 b3f61791 2004-03-21 devnull 	for(; n > 0; n--){
30 b3f61791 2004-03-21 devnull 		x |= ((mpdigit)(*p++)) << s;
31 b3f61791 2004-03-21 devnull 		s -= 8;
32 b3f61791 2004-03-21 devnull 		if(s < 0){
33 b3f61791 2004-03-21 devnull 			b->p[m--] = x;
34 b3f61791 2004-03-21 devnull 			s = Dbits-8;
35 b3f61791 2004-03-21 devnull 			x = 0;
36 b3f61791 2004-03-21 devnull 		}
37 b3f61791 2004-03-21 devnull 	}
38 b3f61791 2004-03-21 devnull 
39 b3f61791 2004-03-21 devnull 	return b;
40 b3f61791 2004-03-21 devnull }