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/* Copyright (C) RSA Data Security, Inc. created 1986, 1996. This is an
unpublished work protected as such under copyright law. This work
contains proprietary, confidential, and trade secret information of
RSA Data Security, Inc. Use, disclosure or reproduction without the
express written authorization of RSA Data Security, Inc. is
prohibited.
*/
#include "global.h"
#include "bigmath.h"
/* BigPdiv POSITIVE DIVIDE
uu=vv * qi+ri
uu in reg of ll cells
vv in reg of kk cells
qi assumed to be ll cells
ri assumed to be kk cells
restriction uu>=0, vv>0
input uu in reg of ll cells
input vv in reg of kk cells
output qi assumed to be ll cells
output ri assumed to be kk cells
restriction uu>=0, vv>0
uu=vv * qi+ri
*/
#define UJN (u[(j+n)/2] & mk[(j+n)%2])
#define VN (v[n/2] & mk[n%2])
#define UT (u[t/2] & mk[t%2])
void BigPdiv (qi, ri, uu, vv, ll, kk)
UINT2 *qi, *ri, *uu, *vv;
unsigned int ll, kk;
{
UINT2 u[2 * MAX_RSA_PRIME_WORDS + 2], us[2 * MAX_RSA_PRIME_WORDS + 2],
v[2 * MAX_RSA_PRIME_WORDS + 2], vs[2 * MAX_RSA_PRIME_WORDS + 2],
q[2 * MAX_RSA_PRIME_WORDS + 2], r[2 * MAX_RSA_PRIME_WORDS + 2],
t1[2 * MAX_RSA_PRIME_WORDS + 2], t2[2 * MAX_RSA_PRIME_WORDS + 2],
t3[2 * MAX_RSA_PRIME_WORDS + 2], mk[2];
int j, l, n, m, t, x;
unsigned int a, b, c, d, e, vh, qq;
if (ll >= kk)
l = ll + 2;
else
l = kk + 2;
mk[0] = 0x00FF;
mk[1] = 0xFF00;
b = 0x0100;
BigConst (u, 0, l);
BigConst (v, 0, l);
BigCopy (u, uu, ll);
BigCopy (us, u, l);
BigCopy (v, vv, kk);
BigCopy (vs, v, l);
/* zero q */
BigConst (q, 0, l);
/* Calculate len of v=n.
*/
for (n = (2 * l) - 1; n >= 0; n--) {
if (VN == 0)
continue;
break;
}
/* Normalize.
*/
a = VN;
if (n % 2 == 1)
a = a >> 8;
d = b / (a+1);
BigConst (t1, d, l);
BigPmpyl (t2, t1, v, l);
BigCopy (v, t2, l);
/* vh=high order digit of normalized v */
vh = VN;
if (n % 2 == 1)
vh = vh >> 8;
BigPmpyl (t2, t1, u, l);
BigCopy (u, t2, l);
/* Calculate len of u=t.
*/
for (t = (2 * l)-1; t >= 0; t--) {
if (UT == 0)
continue;
break;
}
/* calc t = n + m */
m = t - n;
/* Divide u by v.
*/
for (j = m + 1 + n; j > n; j--) {
if (j % 2 == 1)
c = u[j / 2];
else {
a = u[j/2];
a = a << 8;
e = u[(j - 1) / 2];
e = e >> 8;
c = a + e;
}
a = c >> 8;
if (vh == a)
qq = b - 1;
else
qq = c / vh;
BigConst (t1, qq, l);
BigPmpyl (t2, v, t1, l);
Big2Exp (t3, (j - 1 - n) * 8, l);
BigPmpyl (t1, t3, t2, l);
BigSub (t2, u, t1, l);
/* Adjust q.
*/
for (x = 0; ; qq --, x ++) {
if (BigSign (t2, l) != -1)
break;
BigPmpyl (t1, t3, v, l);
BigAdd (t2, t2, t1, l);
}
BigCopy (u, t2, l);
BigConst (t3, qq, l);
Big2Exp (t2, 8, l);
BigPmpyl (t1, q, t2, l);
BigAdd (q, t3, t1, l);
}
/* Check result.
*/
BigPmpyl (t1, vs, q, l);
/* t2 has remainder */
BigSub (t2, us, t1, l);
BigSub (t3, vs, t2, l);
/* transfer results to input registers */
BigCopy (qi, q, ll);
BigCopy (ri, t2, kk);
T_memset ((POINTER)u, 0, sizeof (u));
T_memset ((POINTER)us, 0, sizeof (us));
T_memset ((POINTER)v, 0, sizeof (v));
T_memset ((POINTER)vs, 0, sizeof (vs));
T_memset ((POINTER)q, 0, sizeof (q));
T_memset ((POINTER)r, 0, sizeof (r));
T_memset ((POINTER)t1, 0, sizeof (t1));
T_memset ((POINTER)t2, 0, sizeof (t2));
T_memset ((POINTER)t3, 0, sizeof (t3));
}
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