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