1 files changed, 246 insertions, 237 deletions

diff --git a/libtommath/bn_mp_div.c b/libtommath/bn_mp_div.c
index de4ca04..44e3cb9 100644
--- a/libtommath/bn_mp_div.c
+++ b/libtommath/bn_mp_div.c
@@ -1,4 +1,4 @@
-#include <tommath.h>
+#include "tommath_private.h"
 #ifdef BN_MP_DIV_C
 /* LibTomMath, multiple-precision integer library -- Tom St Denis
  *
@@ -9,77 +9,74 @@
  * Michael Fromberger but has been written from scratch with
  * additional optimizations in place.
  *
- * The library is free for all purposes without any express
- * guarantee it works.
- *
- * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
+ * SPDX-License-Identifier: Unlicense
  */
 
 #ifdef BN_MP_DIV_SMALL
 
 /* slower bit-bang division... also smaller */
-int mp_div(mp_int * a, mp_int * b, mp_int * c, mp_int * d)
+int mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
 {
    mp_int ta, tb, tq, q;
    int    res, n, n2;
 
-  /* is divisor zero ? */
-  if (mp_iszero (b) == 1) {
-    return MP_VAL;
-  }
-
-  /* if a < b then q=0, r = a */
-  if (mp_cmp_mag (a, b) == MP_LT) {
-    if (d != NULL) {
-      res = mp_copy (a, d);
-    } else {
-      res = MP_OKAY;
-    }
-    if (c != NULL) {
-      mp_zero (c);
-    }
-    return res;
-  }
-	
-  /* init our temps */
-  if ((res = mp_init_multi(&ta, &tb, &tq, &q, NULL) != MP_OKAY)) {
-     return res;
-  }
-
-
-  mp_set(&tq, 1);
-  n = mp_count_bits(a) - mp_count_bits(b);
-  if (((res = mp_abs(a, &ta)) != MP_OKAY) ||
-      ((res = mp_abs(b, &tb)) != MP_OKAY) || 
-      ((res = mp_mul_2d(&tb, n, &tb)) != MP_OKAY) ||
-      ((res = mp_mul_2d(&tq, n, &tq)) != MP_OKAY)) {
+   /* is divisor zero ? */
+   if (mp_iszero(b) == MP_YES) {
+      return MP_VAL;
+   }
+
+   /* if a < b then q=0, r = a */
+   if (mp_cmp_mag(a, b) == MP_LT) {
+      if (d != NULL) {
+         res = mp_copy(a, d);
+      } else {
+         res = MP_OKAY;
+      }
+      if (c != NULL) {
+         mp_zero(c);
+      }
+      return res;
+   }
+
+   /* init our temps */
+   if ((res = mp_init_multi(&ta, &tb, &tq, &q, NULL)) != MP_OKAY) {
+      return res;
+   }
+
+
+   mp_set(&tq, 1uL);
+   n = mp_count_bits(a) - mp_count_bits(b);
+   if (((res = mp_abs(a, &ta)) != MP_OKAY) ||
+       ((res = mp_abs(b, &tb)) != MP_OKAY) ||
+       ((res = mp_mul_2d(&tb, n, &tb)) != MP_OKAY) ||
+       ((res = mp_mul_2d(&tq, n, &tq)) != MP_OKAY)) {
       goto LBL_ERR;
-  }
-
-  while (n-- >= 0) {
-     if (mp_cmp(&tb, &ta) != MP_GT) {
-        if (((res = mp_sub(&ta, &tb, &ta)) != MP_OKAY) ||
-            ((res = mp_add(&q, &tq, &q)) != MP_OKAY)) {
-           goto LBL_ERR;
-        }
-     }
-     if (((res = mp_div_2d(&tb, 1, &tb, NULL)) != MP_OKAY) ||
-         ((res = mp_div_2d(&tq, 1, &tq, NULL)) != MP_OKAY)) {
-           goto LBL_ERR;
-     }
-  }
-
-  /* now q == quotient and ta == remainder */
-  n  = a->sign;
-  n2 = (a->sign == b->sign ? MP_ZPOS : MP_NEG);
-  if (c != NULL) {
-     mp_exch(c, &q);
-     c->sign  = (mp_iszero(c) == MP_YES) ? MP_ZPOS : n2;
-  }
-  if (d != NULL) {
-     mp_exch(d, &ta);
-     d->sign = (mp_iszero(d) == MP_YES) ? MP_ZPOS : n;
-  }
+   }
+
+   while (n-- >= 0) {
+      if (mp_cmp(&tb, &ta) != MP_GT) {
+         if (((res = mp_sub(&ta, &tb, &ta)) != MP_OKAY) ||
+             ((res = mp_add(&q, &tq, &q)) != MP_OKAY)) {
+            goto LBL_ERR;
+         }
+      }
+      if (((res = mp_div_2d(&tb, 1, &tb, NULL)) != MP_OKAY) ||
+          ((res = mp_div_2d(&tq, 1, &tq, NULL)) != MP_OKAY)) {
+         goto LBL_ERR;
+      }
+   }
+
+   /* now q == quotient and ta == remainder */
+   n  = a->sign;
+   n2 = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+   if (c != NULL) {
+      mp_exch(c, &q);
+      c->sign  = (mp_iszero(c) == MP_YES) ? MP_ZPOS : n2;
+   }
+   if (d != NULL) {
+      mp_exch(d, &ta);
+      d->sign = (mp_iszero(d) == MP_YES) ? MP_ZPOS : n;
+   }
 LBL_ERR:
    mp_clear_multi(&ta, &tb, &tq, &q, NULL);
    return res;
@@ -87,202 +84,214 @@ LBL_ERR:
 
 #else
 
-/* integer signed division. 
+/* integer signed division.
  * c*b + d == a [e.g. a/b, c=quotient, d=remainder]
  * HAC pp.598 Algorithm 14.20
  *
- * Note that the description in HAC is horribly 
- * incomplete.  For example, it doesn't consider 
- * the case where digits are removed from 'x' in 
- * the inner loop.  It also doesn't consider the 
+ * Note that the description in HAC is horribly
+ * incomplete.  For example, it doesn't consider
+ * the case where digits are removed from 'x' in
+ * the inner loop.  It also doesn't consider the
  * case that y has fewer than three digits, etc..
  *
- * The overall algorithm is as described as 
+ * The overall algorithm is as described as
  * 14.20 from HAC but fixed to treat these cases.
 */
-int mp_div (mp_int * a, mp_int * b, mp_int * c, mp_int * d)
+int mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
 {
-  mp_int  q, x, y, t1, t2;
-  int     res, n, t, i, norm, neg;
-
-  /* is divisor zero ? */
-  if (mp_iszero (b) == 1) {
-    return MP_VAL;
-  }
-
-  /* if a < b then q=0, r = a */
-  if (mp_cmp_mag (a, b) == MP_LT) {
-    if (d != NULL) {
-      res = mp_copy (a, d);
-    } else {
-      res = MP_OKAY;
-    }
-    if (c != NULL) {
-      mp_zero (c);
-    }
-    return res;
-  }
-
-  if ((res = mp_init_size (&q, a->used + 2)) != MP_OKAY) {
-    return res;
-  }
-  q.used = a->used + 2;
-
-  if ((res = mp_init (&t1)) != MP_OKAY) {
-    goto LBL_Q;
-  }
-
-  if ((res = mp_init (&t2)) != MP_OKAY) {
-    goto LBL_T1;
-  }
-
-  if ((res = mp_init_copy (&x, a)) != MP_OKAY) {
-    goto LBL_T2;
-  }
-
-  if ((res = mp_init_copy (&y, b)) != MP_OKAY) {
-    goto LBL_X;
-  }
-
-  /* fix the sign */
-  neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
-  x.sign = y.sign = MP_ZPOS;
-
-  /* normalize both x and y, ensure that y >= b/2, [b == 2**DIGIT_BIT] */
-  norm = mp_count_bits(&y) % DIGIT_BIT;
-  if (norm < (int)(DIGIT_BIT-1)) {
-     norm = (DIGIT_BIT-1) - norm;
-     if ((res = mp_mul_2d (&x, norm, &x)) != MP_OKAY) {
-       goto LBL_Y;
-     }
-     if ((res = mp_mul_2d (&y, norm, &y)) != MP_OKAY) {
-       goto LBL_Y;
-     }
-  } else {
-     norm = 0;
-  }
-
-  /* note hac does 0 based, so if used==5 then its 0,1,2,3,4, e.g. use 4 */
-  n = x.used - 1;
-  t = y.used - 1;
-
-  /* while (x >= y*b**n-t) do { q[n-t] += 1; x -= y*b**{n-t} } */
-  if ((res = mp_lshd (&y, n - t)) != MP_OKAY) { /* y = y*b**{n-t} */
-    goto LBL_Y;
-  }
-
-  while (mp_cmp (&x, &y) != MP_LT) {
-    ++(q.dp[n - t]);
-    if ((res = mp_sub (&x, &y, &x)) != MP_OKAY) {
-      goto LBL_Y;
-    }
-  }
-
-  /* reset y by shifting it back down */
-  mp_rshd (&y, n - t);
-
-  /* step 3. for i from n down to (t + 1) */
-  for (i = n; i >= (t + 1); i--) {
-    if (i > x.used) {
-      continue;
-    }
-
-    /* step 3.1 if xi == yt then set q{i-t-1} to b-1, 
-     * otherwise set q{i-t-1} to (xi*b + x{i-1})/yt */
-    if (x.dp[i] == y.dp[t]) {
-      q.dp[i - t - 1] = ((((mp_digit)1) << DIGIT_BIT) - 1);
-    } else {
-      mp_word tmp;
-      tmp = ((mp_word) x.dp[i]) << ((mp_word) DIGIT_BIT);
-      tmp |= ((mp_word) x.dp[i - 1]);
-      tmp /= ((mp_word) y.dp[t]);
-      if (tmp > (mp_word) MP_MASK)
-        tmp = MP_MASK;
-      q.dp[i - t - 1] = (mp_digit) (tmp & (mp_word) (MP_MASK));
-    }
-
-    /* while (q{i-t-1} * (yt * b + y{t-1})) > 
-             xi * b**2 + xi-1 * b + xi-2 
-     
-       do q{i-t-1} -= 1; 
-    */
-    q.dp[i - t - 1] = (q.dp[i - t - 1] + 1) & MP_MASK;
-    do {
-      q.dp[i - t - 1] = (q.dp[i - t - 1] - 1) & MP_MASK;
-
-      /* find left hand */
-      mp_zero (&t1);
-      t1.dp[0] = (t - 1 < 0) ? 0 : y.dp[t - 1];
-      t1.dp[1] = y.dp[t];
-      t1.used = 2;
-      if ((res = mp_mul_d (&t1, q.dp[i - t - 1], &t1)) != MP_OKAY) {
-        goto LBL_Y;
+   mp_int  q, x, y, t1, t2;
+   int     res, n, t, i, norm, neg;
+
+   /* is divisor zero ? */
+   if (mp_iszero(b) == MP_YES) {
+      return MP_VAL;
+   }
+
+   /* if a < b then q=0, r = a */
+   if (mp_cmp_mag(a, b) == MP_LT) {
+      if (d != NULL) {
+         res = mp_copy(a, d);
+      } else {
+         res = MP_OKAY;
+      }
+      if (c != NULL) {
+         mp_zero(c);
+      }
+      return res;
+   }
+
+   if ((res = mp_init_size(&q, a->used + 2)) != MP_OKAY) {
+      return res;
+   }
+   q.used = a->used + 2;
+
+   if ((res = mp_init(&t1)) != MP_OKAY) {
+      goto LBL_Q;
+   }
+
+   if ((res = mp_init(&t2)) != MP_OKAY) {
+      goto LBL_T1;
+   }
+
+   if ((res = mp_init_copy(&x, a)) != MP_OKAY) {
+      goto LBL_T2;
+   }
+
+   if ((res = mp_init_copy(&y, b)) != MP_OKAY) {
+      goto LBL_X;
+   }
+
+   /* fix the sign */
+   neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+   x.sign = y.sign = MP_ZPOS;
+
+   /* normalize both x and y, ensure that y >= b/2, [b == 2**DIGIT_BIT] */
+   norm = mp_count_bits(&y) % DIGIT_BIT;
+   if (norm < (DIGIT_BIT - 1)) {
+      norm = (DIGIT_BIT - 1) - norm;
+      if ((res = mp_mul_2d(&x, norm, &x)) != MP_OKAY) {
+         goto LBL_Y;
       }
+      if ((res = mp_mul_2d(&y, norm, &y)) != MP_OKAY) {
+         goto LBL_Y;
+      }
+   } else {
+      norm = 0;
+   }
 
-      /* find right hand */
-      t2.dp[0] = (i - 2 < 0) ? 0 : x.dp[i - 2];
-      t2.dp[1] = (i - 1 < 0) ? 0 : x.dp[i - 1];
-      t2.dp[2] = x.dp[i];
-      t2.used = 3;
-    } while (mp_cmp_mag(&t1, &t2) == MP_GT);
+   /* note hac does 0 based, so if used==5 then its 0,1,2,3,4, e.g. use 4 */
+   n = x.used - 1;
+   t = y.used - 1;
 
-    /* step 3.3 x = x - q{i-t-1} * y * b**{i-t-1} */
-    if ((res = mp_mul_d (&y, q.dp[i - t - 1], &t1)) != MP_OKAY) {
+   /* while (x >= y*b**n-t) do { q[n-t] += 1; x -= y*b**{n-t} } */
+   if ((res = mp_lshd(&y, n - t)) != MP_OKAY) { /* y = y*b**{n-t} */
       goto LBL_Y;
-    }
+   }
 
-    if ((res = mp_lshd (&t1, i - t - 1)) != MP_OKAY) {
-      goto LBL_Y;
-    }
+   while (mp_cmp(&x, &y) != MP_LT) {
+      ++(q.dp[n - t]);
+      if ((res = mp_sub(&x, &y, &x)) != MP_OKAY) {
+         goto LBL_Y;
+      }
+   }
 
-    if ((res = mp_sub (&x, &t1, &x)) != MP_OKAY) {
-      goto LBL_Y;
-    }
+   /* reset y by shifting it back down */
+   mp_rshd(&y, n - t);
 
-    /* if x < 0 then { x = x + y*b**{i-t-1}; q{i-t-1} -= 1; } */
-    if (x.sign == MP_NEG) {
-      if ((res = mp_copy (&y, &t1)) != MP_OKAY) {
-        goto LBL_Y;
+   /* step 3. for i from n down to (t + 1) */
+   for (i = n; i >= (t + 1); i--) {
+      if (i > x.used) {
+         continue;
       }
-      if ((res = mp_lshd (&t1, i - t - 1)) != MP_OKAY) {
-        goto LBL_Y;
+
+      /* step 3.1 if xi == yt then set q{i-t-1} to b-1,
+       * otherwise set q{i-t-1} to (xi*b + x{i-1})/yt */
+      if (x.dp[i] == y.dp[t]) {
+         q.dp[(i - t) - 1] = ((mp_digit)1 << (mp_digit)DIGIT_BIT) - (mp_digit)1;
+      } else {
+         mp_word tmp;
+         tmp = (mp_word)x.dp[i] << (mp_word)DIGIT_BIT;
+         tmp |= (mp_word)x.dp[i - 1];
+         tmp /= (mp_word)y.dp[t];
+         if (tmp > (mp_word)MP_MASK) {
+            tmp = MP_MASK;
+         }
+         q.dp[(i - t) - 1] = (mp_digit)(tmp & (mp_word)MP_MASK);
+      }
+
+      /* while (q{i-t-1} * (yt * b + y{t-1})) >
+               xi * b**2 + xi-1 * b + xi-2
+
+         do q{i-t-1} -= 1;
+      */
+      q.dp[(i - t) - 1] = (q.dp[(i - t) - 1] + 1uL) & (mp_digit)MP_MASK;
+      do {
+         q.dp[(i - t) - 1] = (q.dp[(i - t) - 1] - 1uL) & (mp_digit)MP_MASK;
+
+         /* find left hand */
+         mp_zero(&t1);
+         t1.dp[0] = ((t - 1) < 0) ? 0u : y.dp[t - 1];
+         t1.dp[1] = y.dp[t];
+         t1.used = 2;
+         if ((res = mp_mul_d(&t1, q.dp[(i - t) - 1], &t1)) != MP_OKAY) {
+            goto LBL_Y;
+         }
+
+         /* find right hand */
+         t2.dp[0] = ((i - 2) < 0) ? 0u : x.dp[i - 2];
+         t2.dp[1] = ((i - 1) < 0) ? 0u : x.dp[i - 1];
+         t2.dp[2] = x.dp[i];
+         t2.used = 3;
+      } while (mp_cmp_mag(&t1, &t2) == MP_GT);
+
+      /* step 3.3 x = x - q{i-t-1} * y * b**{i-t-1} */
+      if ((res = mp_mul_d(&y, q.dp[(i - t) - 1], &t1)) != MP_OKAY) {
+         goto LBL_Y;
+      }
+
+      if ((res = mp_lshd(&t1, (i - t) - 1)) != MP_OKAY) {
+         goto LBL_Y;
+      }
+
+      if ((res = mp_sub(&x, &t1, &x)) != MP_OKAY) {
+         goto LBL_Y;
       }
-      if ((res = mp_add (&x, &t1, &x)) != MP_OKAY) {
-        goto LBL_Y;
+
+      /* if x < 0 then { x = x + y*b**{i-t-1}; q{i-t-1} -= 1; } */
+      if (x.sign == MP_NEG) {
+         if ((res = mp_copy(&y, &t1)) != MP_OKAY) {
+            goto LBL_Y;
+         }
+         if ((res = mp_lshd(&t1, (i - t) - 1)) != MP_OKAY) {
+            goto LBL_Y;
+         }
+         if ((res = mp_add(&x, &t1, &x)) != MP_OKAY) {
+            goto LBL_Y;
+         }
+
+         q.dp[(i - t) - 1] = (q.dp[(i - t) - 1] - 1uL) & MP_MASK;
       }
+   }
 
-      q.dp[i - t - 1] = (q.dp[i - t - 1] - 1UL) & MP_MASK;
-    }
-  }
-
-  /* now q is the quotient and x is the remainder 
-   * [which we have to normalize] 
-   */
-  
-  /* get sign before writing to c */
-  x.sign = x.used == 0 ? MP_ZPOS : a->sign;
-
-  if (c != NULL) {
-    mp_clamp (&q);
-    mp_exch (&q, c);
-    c->sign = neg;
-  }
-
-  if (d != NULL) {
-    mp_div_2d (&x, norm, &x, NULL);
-    mp_exch (&x, d);
-  }
-
-  res = MP_OKAY;
-
-LBL_Y:mp_clear (&y);
-LBL_X:mp_clear (&x);
-LBL_T2:mp_clear (&t2);
-LBL_T1:mp_clear (&t1);
-LBL_Q:mp_clear (&q);
-  return res;
+   /* now q is the quotient and x is the remainder
+    * [which we have to normalize]
+    */
+
+   /* get sign before writing to c */
+   x.sign = (x.used == 0) ? MP_ZPOS : a->sign;
+
+   if (c != NULL) {
+      mp_clamp(&q);
+      mp_exch(&q, c);
+      c->sign = neg;
+   }
+
+   if (d != NULL) {
+      if ((res = mp_div_2d(&x, norm, &x, NULL)) != MP_OKAY) {
+         goto LBL_Y;
+      }
+      mp_exch(&x, d);
+   }
+
+   res = MP_OKAY;
+
+LBL_Y:
+   mp_clear(&y);
+LBL_X:
+   mp_clear(&x);
+LBL_T2:
+   mp_clear(&t2);
+LBL_T1:
+   mp_clear(&t1);
+LBL_Q:
+   mp_clear(&q);
+   return res;
 }
 
 #endif
 
 #endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */