ref: 0c9cb17126859a6121dd5d79a4e1d664e4e9ba48
dir: /libmp/mptobe.c/
#include "os.h"
#include <mp.h>
#include "dat.h"
// convert an mpint into a big endian byte array (most significant byte first; left adjusted)
// return number of bytes converted
// if p == nil, allocate and result array
int
mptobe(mpint *b, uchar *p, uint n, uchar **pp)
{
int m;
m = (mpsignif(b)+7)/8;
if(m == 0)
m++;
if(p == nil){
n = m;
p = malloc(n);
if(p == nil)
sysfatal("mptobe: %r");
setmalloctag(p, getcallerpc(&b));
} else {
if(n < m)
return -1;
if(n > m)
memset(p+m, 0, n-m);
}
if(pp != nil)
*pp = p;
mptober(b, p, m);
return m;
}