first batch of simplifications

mp_abs.c

@@ -9,10 +9,9 @@
  */
 mp_err mp_abs(const mp_int *a, mp_int *b)
 {
-   mp_err     err;
-
    /* copy a to b */
    if (a != b) {
+      mp_err err;
       if ((err = mp_copy(a, b)) != MP_OKAY) {
          return err;
       }

mp_add.c

@@ -6,33 +6,24 @@
 /* high level addition (handles signs) */
 mp_err mp_add(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   mp_sign sa, sb;
-   mp_err err;
-
-   /* get sign of both inputs */
-   sa = a->sign;
-   sb = b->sign;
-
    /* handle two cases, not four */
-   if (sa == sb) {
+   if (a->sign == b->sign) {
       /* both positive or both negative */
       /* add their magnitudes, copy the sign */
-      c->sign = sa;
-      err = s_mp_add(a, b, c);
-   } else {
-      /* one positive, the other negative */
-      /* subtract the one with the greater magnitude from */
-      /* the one of the lesser magnitude.  The result gets */
-      /* the sign of the one with the greater magnitude. */
-      if (mp_cmp_mag(a, b) == MP_LT) {
-         c->sign = sb;
-         err = s_mp_sub(b, a, c);
-      } else {
-         c->sign = sa;
-         err = s_mp_sub(a, b, c);
-      }
+      c->sign = a->sign;
+      return s_mp_add(a, b, c);
    }
-   return err;
+
+   /* one positive, the other negative */
+   /* subtract the one with the greater magnitude from */
+   /* the one of the lesser magnitude. The result gets */
+   /* the sign of the one with the greater magnitude. */
+   if (mp_cmp_mag(a, b) == MP_LT) {
+      MP_EXCH(const mp_int *, a, b);
+   }
+
+   c->sign = a->sign;
+   return s_mp_sub(a, b, c);
 }
 
 #endif

mp_clear_multi.c

@@ -7,12 +7,11 @@
 
 void mp_clear_multi(mp_int *mp, ...)
 {
-   mp_int *next_mp = mp;
    va_list args;
    va_start(args, mp);
-   while (next_mp != NULL) {
-      mp_clear(next_mp);
-      next_mp = va_arg(args, mp_int *);
+   while (mp != NULL) {
+      mp_clear(mp);
+      mp = va_arg(args, mp_int *);
    }
    va_end(args);
 }

mp_cmp.c

@@ -8,19 +8,14 @@ mp_ord mp_cmp(const mp_int *a, const mp_int *b)
 {
    /* compare based on sign */
    if (a->sign != b->sign) {
-      if (a->sign == MP_NEG) {
-         return MP_LT;
-      } else {
-         return MP_GT;
-      }
+      return a->sign == MP_NEG ? MP_LT : MP_GT;
    }
 
-   /* compare digits */
+   /* if negative compare opposite direction */
    if (a->sign == MP_NEG) {
-      /* if negative compare opposite direction */
-      return mp_cmp_mag(b, a);
-   } else {
-      return mp_cmp_mag(a, b);
+      MP_EXCH(const mp_int *, a, b);
    }
+
+   return mp_cmp_mag(a, b);
 }
 #endif

mp_cmp_d.c

@@ -17,12 +17,10 @@ mp_ord mp_cmp_d(const mp_int *a, mp_digit b)
    }
 
    /* compare the only digit of a to b */
-   if (a->dp[0] > b) {
-      return MP_GT;
-   } else if (a->dp[0] < b) {
-      return MP_LT;
-   } else {
-      return MP_EQ;
+   if (a->dp[0] != b) {
+      return a->dp[0] > b ? MP_GT : MP_LT;
    }
+
+   return MP_EQ;
 }
 #endif

mp_cmp_mag.c

@@ -6,34 +6,20 @@
 /* compare maginitude of two ints (unsigned) */
 mp_ord mp_cmp_mag(const mp_int *a, const mp_int *b)
 {
-   int     n;
-   const mp_digit *tmpa, *tmpb;
+   int n;
 
    /* compare based on # of non-zero digits */
-   if (a->used > b->used) {
-      return MP_GT;
+   if (a->used != b->used) {
+      return a->used > b->used ? MP_GT : MP_LT;
    }
 
-   if (a->used < b->used) {
-      return MP_LT;
-   }
-
-   /* alias for a */
-   tmpa = a->dp + (a->used - 1);
-
-   /* alias for b */
-   tmpb = b->dp + (a->used - 1);
-
    /* compare based on digits  */
-   for (n = 0; n < a->used; ++n, --tmpa, --tmpb) {
-      if (*tmpa > *tmpb) {
-         return MP_GT;
-      }
-
-      if (*tmpa < *tmpb) {
-         return MP_LT;
+   for (n = a->used; n --> 0;) {
+      if (a->dp[n] != b->dp[n]) {
+         return a->dp[n] > b->dp[n] ? MP_GT : MP_LT;
       }
    }
+
    return MP_EQ;
 }
 #endif

mp_cnt_lsb.c

@@ -3,15 +3,15 @@
 /* LibTomMath, multiple-precision integer library -- Tom St Denis */
 /* SPDX-License-Identifier: Unlicense */
 
-static const int lnz[16] = {
+static const char lnz[16] = {
    4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
 };
 
 /* Counts the number of lsbs which are zero before the first zero bit */
 int mp_cnt_lsb(const mp_int *a)
 {
    int x;
-   mp_digit q, qq;
+   mp_digit q;
 
    /* easy out */
    if (mp_iszero(a)) {
@@ -25,11 +25,12 @@ int mp_cnt_lsb(const mp_int *a)
 
    /* now scan this digit until a 1 is found */
    if ((q & 1u) == 0u) {
+      mp_digit p;
       do {
-         qq  = q & 15u;
-         x  += lnz[qq];
+         p = q & 15u;
+         x += lnz[p];
          q >>= 4;
-      } while (qq == 0u);
+      } while (p == 0u);
    }
    return x;
 }

mp_copy.c

@@ -7,8 +7,6 @@
 mp_err mp_copy(const mp_int *a, mp_int *b)
 {
    int n;
-   mp_digit *tmpa, *tmpb;
-   mp_err err;
 
    /* if dst == src do nothing */
    if (a == b) {
@@ -17,27 +15,21 @@ mp_err mp_copy(const mp_int *a, mp_int *b)
 
    /* grow dest */
    if (b->alloc < a->used) {
+      mp_err err;
       if ((err = mp_grow(b, a->used)) != MP_OKAY) {
          return err;
       }
    }
 
    /* zero b and copy the parameters over */
-   /* pointer aliases */
-
-   /* source */
-   tmpa = a->dp;
-
-   /* destination */
-   tmpb = b->dp;
 
    /* copy all the digits */
    for (n = 0; n < a->used; n++) {
-      *tmpb++ = *tmpa++;
+      b->dp[n] = a->dp[n];
    }
 
    /* clear high digits */
-   MP_ZERO_DIGITS(tmpb, b->used - n);
+   MP_ZERO_DIGITS(b->dp + a->used, b->used - a->used);
 
    /* copy used count and sign */
    b->used = a->used;

mp_div.c

@@ -15,14 +15,14 @@ mp_err mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
    /* if a < b then q = 0, r = a */
    if (mp_cmp_mag(a, b) == MP_LT) {
       if (d != NULL) {
-         err = mp_copy(a, d);
-      } else {
-         err = MP_OKAY;
+         if ((err = mp_copy(a, d)) != MP_OKAY) {
+            return err;
+         }
       }
       if (c != NULL) {
          mp_zero(c);
       }
-      return err;
+      return MP_OKAY;
    }
 
    if (MP_HAS(S_MP_DIV_RECURSIVE)
@@ -31,11 +31,12 @@ mp_err mp_div(const mp_int *a, const mp_int *b, mp_int *c, mp_int *d)
       err = s_mp_div_recursive(a, b, c, d);
    } else if (MP_HAS(S_MP_DIV_SCHOOL)) {
       err = s_mp_div_school(a, b, c, d);
-   } else {
+   } else if (MP_HAS(S_MP_DIV_SMALL)) {
       err = s_mp_div_small(a, b, c, d);
+   } else {
+      err = MP_VAL;
    }
 
    return err;
 }
 #endif
-

mp_div_3.c

@@ -7,7 +7,7 @@
 mp_err mp_div_3(const mp_int *a, mp_int *c, mp_digit *d)
 {
    mp_int   q;
-   mp_word  w, t;
+   mp_word  w;
    mp_digit b;
    mp_err   err;
    int      ix;
@@ -22,7 +22,8 @@ mp_err mp_div_3(const mp_int *a, mp_int *c, mp_digit *d)
    q.used = a->used;
    q.sign = a->sign;
    w = 0;
-   for (ix = a->used - 1; ix >= 0; ix--) {
+   for (ix = a->used; ix --> 0;) {
+      mp_word t;
       w = (w << (mp_word)MP_DIGIT_BIT) | (mp_word)a->dp[ix];
 
       if (w >= 3u) {
@@ -57,7 +58,7 @@ mp_err mp_div_3(const mp_int *a, mp_int *c, mp_digit *d)
    }
    mp_clear(&q);
 
-   return err;
+   return MP_OKAY;
 }
 
 #endif

mp_exch.c

@@ -8,10 +8,6 @@
  */
 void mp_exch(mp_int *a, mp_int *b)
 {
-   mp_int  t;
-
-   t  = *a;
-   *a = *b;
-   *b = t;
+   MP_EXCH(mp_int, *a, *b);
 }
 #endif

mp_exptmod.c

@@ -64,13 +64,15 @@ mp_err mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
    /* if the modulus is odd or dr != 0 use the montgomery method */
    if (MP_HAS(S_MP_EXPTMOD_FAST) && (mp_isodd(P) || (dr != 0))) {
       return s_mp_exptmod_fast(G, X, P, Y, dr);
-   } else if (MP_HAS(S_MP_EXPTMOD)) {
-      /* otherwise use the generic Barrett reduction technique */
+   }
+
+   /* otherwise use the generic Barrett reduction technique */
+   if (MP_HAS(S_MP_EXPTMOD)) {
       return s_mp_exptmod(G, X, P, Y, 0);
-   } else {
-      /* no exptmod for evens */
-      return MP_VAL;
    }
+
+   /* no exptmod for evens */
+   return MP_VAL;
 }
 
 #endif

mp_exteuclid.c

@@ -65,7 +65,6 @@ mp_err mp_exteuclid(const mp_int *a, const mp_int *b, mp_int *U1, mp_int *U2, mp
       mp_exch(U3, &u3);
    }
 
-   err = MP_OKAY;
 LBL_ERR:
    mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
    return err;

mp_fread.c

@@ -32,15 +32,15 @@ mp_err mp_fread(mp_int *a, int radix, FILE *stream)
    mp_zero(a);
 
    do {
-      int y;
+      uint8_t y;
       unsigned pos;
       ch = (radix <= 36) ? MP_TOUPPER(ch) : ch;
       pos = (unsigned)(ch - (int)'(');
       if (MP_RMAP_REVERSE_SIZE < pos) {
          break;
       }
 
-      y = (int)s_mp_rmap_reverse[pos];
+      y = s_mp_rmap_reverse[pos];
 
       if ((y == 0xff) || (y >= radix)) {
          break;
@@ -50,7 +50,7 @@ mp_err mp_fread(mp_int *a, int radix, FILE *stream)
       if ((err = mp_mul_d(a, (mp_digit)radix, a)) != MP_OKAY) {
          return err;
       }
-      if ((err = mp_add_d(a, (mp_digit)y, a)) != MP_OKAY) {
+      if ((err = mp_add_d(a, y, a)) != MP_OKAY) {
          return err;
       }
    } while ((ch = fgetc(stream)) != EOF);

mp_from_sbin.c

@@ -14,11 +14,7 @@ mp_err mp_from_sbin(mp_int *a, const uint8_t *buf, size_t size)
    }
 
    /* first byte is 0 for positive, non-zero for negative */
-   if (buf[0] == (uint8_t)0) {
-      a->sign = MP_ZPOS;
-   } else {
-      a->sign = MP_NEG;
-   }
+   a->sign = (buf[0] == (uint8_t)0) ? MP_ZPOS : MP_NEG;
 
    return MP_OKAY;
 }