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