add feature detection macro MP_HAS

Author: minad

bn_mp_div_d.c

@@ -43,12 +43,10 @@ mp_err mp_div_d(const mp_int *a, mp_digit b, mp_int *c, mp_digit *d)
       return MP_OKAY;
    }
 
-#ifdef BN_MP_DIV_3_C
    /* three? */
-   if (b == 3u) {
+   if (MP_HAS(MP_DIV_3) && b == 3u) {
       return mp_div_3(a, c, d);
    }
-#endif
 
    /* no easy answer [c'est la vie].  Just division */
    if ((err = mp_init_size(&q, a->used)) != MP_OKAY) {

bn_mp_exptmod.c

@@ -19,10 +19,13 @@ mp_err mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
 
    /* if exponent X is negative we have to recurse */
    if (X->sign == MP_NEG) {
-#ifdef BN_MP_INVMOD_C
       mp_int tmpG, tmpX;
       mp_err err;
 
+      if (!MP_HAS(MP_INVMOD)) {
+         return MP_VAL;
+      }
+
       /* first compute 1/G mod P */
       if ((err = mp_init(&tmpG)) != MP_OKAY) {
          return err;
@@ -46,50 +49,32 @@ mp_err mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y)
       err = mp_exptmod(&tmpG, &tmpX, P, Y);
       mp_clear_multi(&tmpG, &tmpX, NULL);
       return err;
-#else
-      /* no invmod */
-      return MP_VAL;
-#endif
    }
 
    /* modified diminished radix reduction */
-#if defined(BN_MP_REDUCE_IS_2K_L_C) && defined(BN_MP_REDUCE_2K_L_C) && defined(BN_S_MP_EXPTMOD_C)
-   if (mp_reduce_is_2k_l(P) == MP_YES) {
+   if (MP_HAS(MP_REDUCE_IS_2K_L) && MP_HAS(MP_REDUCE_2K_L) && MP_HAS(S_MP_EXPTMOD) &&
+       mp_reduce_is_2k_l(P) == MP_YES) {
       return s_mp_exptmod(G, X, P, Y, 1);
    }
-#endif
 
-#ifdef BN_MP_DR_IS_MODULUS_C
-   /* is it a DR modulus? */
-   dr = (mp_dr_is_modulus(P) == MP_YES) ? 1 : 0;
-#else
-   /* default to no */
-   dr = 0;
-#endif
+   /* is it a DR modulus? default to no */
+   dr = MP_HAS(MP_DR_IS_MODULUS) && mp_dr_is_modulus(P) == MP_YES ? 1 : 0;
 
-#ifdef BN_MP_REDUCE_IS_2K_C
    /* if not, is it a unrestricted DR modulus? */
-   if (dr == 0) {
+   if (MP_HAS(MP_REDUCE_IS_2K) && dr == 0) {
       dr = (mp_reduce_is_2k(P) == MP_YES) ? 2 : 0;
    }
-#endif
 
    /* if the modulus is odd or dr != 0 use the montgomery method */
-#ifdef BN_S_MP_EXPTMOD_FAST_C
-   if (MP_IS_ODD(P) || (dr !=  0)) {
+   if (MP_HAS(S_MP_EXPTMOD_FAST) && (MP_IS_ODD(P) || (dr != 0))) {
       return s_mp_exptmod_fast(G, X, P, Y, dr);
-   } else {
-#endif
-#ifdef BN_S_MP_EXPTMOD_C
+   } else if (MP_HAS(S_MP_EXPTMOD)) {
       /* otherwise use the generic Barrett reduction technique */
       return s_mp_exptmod(G, X, P, Y, 0);
-#else
+   } else {
       /* no exptmod for evens */
       return MP_VAL;
-#endif
-#ifdef BN_S_MP_EXPTMOD_FAST_C
    }
-#endif
 }
 
 #endif

bn_mp_invmod.c

@@ -11,17 +11,13 @@ mp_err mp_invmod(const mp_int *a, const mp_int *b, mp_int *c)
       return MP_VAL;
    }
 
-#ifdef BN_S_MP_INVMOD_FAST_C
    /* if the modulus is odd we can use a faster routine instead */
-   if (MP_IS_ODD(b)) {
+   if (MP_HAS(S_MP_INVMOD_FAST) && MP_IS_ODD(b)) {
       return s_mp_invmod_fast(a, b, c);
    }
-#endif
 
-#ifdef BN_S_MP_INVMOD_SLOW_C
-   return s_mp_invmod_slow(a, b, c);
-#else
-   return MP_VAL;
-#endif
+   return MP_HAS(S_MP_INVMOD_SLOW)
+          ? s_mp_invmod_slow(a, b, c)
+          : MP_VAL;
 }
 #endif

bn_mp_mul.c

@@ -6,80 +6,46 @@
 /* high level multiplication (handles sign) */
 mp_err mp_mul(const mp_int *a, const mp_int *b, mp_int *c)
 {
-   mp_err  err;
-   mp_sign neg;
-#ifdef BN_S_MP_BALANCE_MUL_C
-   int len_b, len_a;
-#endif
-   neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
-#ifdef BN_S_MP_BALANCE_MUL_C
-   len_a = a->used;
-   len_b = b->used;
-
-   if (len_a == len_b) {
-      goto GO_ON;
-   }
-   /*
-    * Check sizes. The smaller one needs to be larger than the Karatsuba cut-off.
-    * The bigger one needs to be at least about one KARATSUBA_MUL_CUTOFF bigger
-    * to make some sense, but it depends on architecture, OS, position of the
-    * stars... so YMMV.
-    * Using it to cut the input into slices small enough for fast_s_mp_mul_digs
-    * was actually slower on the author's machine, but YMMV.
-    */
-   if ((MP_MIN(len_a, len_b) < MP_KARATSUBA_MUL_CUTOFF)
-       || ((MP_MAX(len_a, len_b) / 2) < MP_KARATSUBA_MUL_CUTOFF)) {
-      goto GO_ON;
-   }
-   /*
-    * Not much effect was observed below a ratio of 1:2, but again: YMMV.
-    */
-   if ((MP_MAX(len_a, len_b) /  MP_MIN(len_a, len_b)) < 2) {
-      goto GO_ON;
-   }
-
-   err = s_mp_balance_mul(a,b,c);
-   goto END;
-
-GO_ON:
-#endif
+   mp_err err;
+   int min_len = MP_MIN(a->used, b->used),
+       max_len = MP_MAX(a->used, b->used),
+       digs = a->used + b->used + 1;
+   mp_sign neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
 
-   /* use Toom-Cook? */
-#ifdef BN_S_MP_TOOM_MUL_C
-   if (MP_MIN(a->used, b->used) >= MP_TOOM_MUL_CUTOFF) {
+   if (MP_HAS(S_MP_BALANCE_MUL) &&
+       /* Check sizes. The smaller one needs to be larger than the Karatsuba cut-off.
+        * The bigger one needs to be at least about one MP_KARATSUBA_MUL_CUTOFF bigger
+        * to make some sense, but it depends on architecture, OS, position of the
+        * stars... so YMMV.
+        * Using it to cut the input into slices small enough for fast_s_mp_mul_digs
+        * was actually slower on the author's machine, but YMMV.
+        */
+       (min_len >= MP_KARATSUBA_MUL_CUTOFF) &&
+       (max_len / 2 >= MP_KARATSUBA_MUL_CUTOFF) &&
+       /* Not much effect was observed below a ratio of 1:2, but again: YMMV. */
+       (max_len >= (2 * min_len))) {
+      err = s_mp_balance_mul(a,b,c);
+   } else if (MP_HAS(S_MP_TOOM_MUL) &&
+              (min_len >= MP_TOOM_MUL_CUTOFF)) {
       err = s_mp_toom_mul(a, b, c);
-   } else
-#endif
-#ifdef BN_S_MP_KARATSUBA_MUL_C
-      /* use Karatsuba? */
-      if (MP_MIN(a->used, b->used) >= MP_KARATSUBA_MUL_CUTOFF) {
-         err = s_mp_karatsuba_mul(a, b, c);
-      } else
-#endif
-      {
-         /* can we use the fast multiplier?
-          *
-          * The fast multiplier can be used if the output will
-          * have less than MP_WARRAY digits and the number of
-          * digits won't affect carry propagation
-          */
-         int     digs = a->used + b->used + 1;
-
-#ifdef BN_S_MP_MUL_DIGS_FAST_C
-         if ((digs < MP_WARRAY) &&
-             (MP_MIN(a->used, b->used) <= MP_MAXFAST)) {
-            err = s_mp_mul_digs_fast(a, b, c, digs);
-         } else
-#endif
-         {
-#ifdef BN_S_MP_MUL_DIGS_C
-            err = s_mp_mul_digs(a, b, c, a->used + b->used + 1);
-#else
-            err = MP_VAL;
-#endif
-         }
-      }
-END:
+   } else if (MP_HAS(S_MP_KARATSUBA_MUL) &&
+              (min_len >= MP_KARATSUBA_MUL_CUTOFF)) {
+      err = s_mp_karatsuba_mul(a, b, c);
+   } else if (MP_HAS(S_MP_MUL_DIGS_FAST) &&
+              /* can we use the fast multiplier?
+               *
+               * The fast multiplier can be used if the output will
+               * have less than MP_WARRAY digits and the number of
+               * digits won't affect carry propagation
+               */
+              (digs < MP_WARRAY) &&
+              (min_len <= MP_MAXFAST)) {
+      err = s_mp_mul_digs_fast(a, b, c, digs);
+   } else if (MP_HAS(S_MP_MUL_DIGS)) {
+      err = s_mp_mul_digs(a, b, c, digs);
+   } else {
+      err = MP_VAL;
+   }
    c->sign = (c->used > 0) ? neg : MP_ZPOS;
    return err;
 }

bn_mp_reduce.c

@@ -26,21 +26,17 @@ mp_err mp_reduce(mp_int *x, const mp_int *m, const mp_int *mu)
       if ((err = mp_mul(&q, mu, &q)) != MP_OKAY) {
          goto CLEANUP;
       }
-   } else {
-#ifdef BN_S_MP_MUL_HIGH_DIGS_C
+   } else if (MP_HAS(S_MP_MUL_HIGH_DIGS)) {
       if ((err = s_mp_mul_high_digs(&q, mu, &q, um)) != MP_OKAY) {
          goto CLEANUP;
       }
-#elif defined(BN_S_MP_MUL_HIGH_DIGS_FAST_C)
+   } else if (MP_HAS(S_MP_MUL_HIGH_DIGS_FAST)) {
       if ((err = s_mp_mul_high_digs_fast(&q, mu, &q, um)) != MP_OKAY) {
          goto CLEANUP;
       }
-#else
-      {
-         err = MP_VAL;
-         goto CLEANUP;
-      }
-#endif
+   } else {
+      err = MP_VAL;
+      goto CLEANUP;
    }
 
    /* q3 = q2 / b**(k+1) */

bn_mp_sqr.c

@@ -7,35 +7,21 @@
 mp_err mp_sqr(const mp_int *a, mp_int *b)
 {
    mp_err err;
-
-#ifdef BN_S_MP_TOOM_SQR_C
-   /* use Toom-Cook? */
-   if (a->used >= MP_TOOM_SQR_CUTOFF) {
+   if (MP_HAS(S_MP_TOOM_SQR) && /* use Toom-Cook? */
+       a->used >= MP_TOOM_SQR_CUTOFF) {
       err = s_mp_toom_sqr(a, b);
-      /* Karatsuba? */
-   } else
-#endif
-#ifdef BN_S_MP_KARATSUBA_SQR_C
-      if (a->used >= MP_KARATSUBA_SQR_CUTOFF) {
-         err = s_mp_karatsuba_sqr(a, b);
-      } else
-#endif
-      {
-#ifdef BN_S_MP_SQR_FAST_C
-         /* can we use the fast comba multiplier? */
-         if ((((a->used * 2) + 1) < MP_WARRAY) &&
-             (a->used < (MP_MAXFAST / 2))) {
-            err = s_mp_sqr_fast(a, b);
-         } else
-#endif
-         {
-#ifdef BN_S_MP_SQR_C
-            err = s_mp_sqr(a, b);
-#else
-            err = MP_VAL;
-#endif
-         }
-      }
+   } else if (MP_HAS(S_MP_KARATSUBA_SQR) &&  /* Karatsuba? */
+              a->used >= MP_KARATSUBA_SQR_CUTOFF) {
+      err = s_mp_karatsuba_sqr(a, b);
+   } else if (MP_HAS(S_MP_SQR_FAST) && /* can we use the fast comba multiplier? */
+              (((a->used * 2) + 1) < MP_WARRAY) &&
+              (a->used < (MP_MAXFAST / 2))) {
+      err = s_mp_sqr_fast(a, b);
+   } else if (MP_HAS(S_MP_SQR)) {
+      err = s_mp_sqr(a, b);
+   } else {
+      err = MP_VAL;
+   }
    b->sign = MP_ZPOS;
    return err;
 }

bn_s_mp_exptmod.c

@@ -5,8 +5,10 @@
 
 #ifdef MP_LOW_MEM
 #   define TAB_SIZE 32
+#   define MAX_WINSIZE 5
 #else
 #   define TAB_SIZE 256
+#   define MAX_WINSIZE 0
 #endif
 
 mp_err s_mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y, int redmode)
@@ -35,11 +37,7 @@ mp_err s_mp_exptmod(const mp_int *G, const mp_int *X, const mp_int *P, mp_int *Y
       winsize = 8;
    }
 
-#ifdef MP_LOW_MEM
-   if (winsize > 5) {
-      winsize = 5;
-   }
-#endif
+   winsize = MAX_WINSIZE ? MP_MIN(MAX_WINSIZE, winsize) : winsize;
 
    /* init M array */
    /* init first cell */