commit 9a5bfc035045db0ba5f3c5b51545917deea7441a
author David Benjamin <davidben@google.com> Fri Jan 19 09:52:16 2018 -0500
committer Adam Langley <agl@google.com> Fri Feb 02 18:44:01 2018 +0000
tree d87286e3245f97d5854fe59b9f1b6a3c8de89067
parent 2ccdf584aa3304e5c9aaa221cc1fd1368c62d096

Tidy up BN_mod_mul_montgomery.

This matches bn_mod_mul_montgomery_small and removes a bit of
unnecessary stuttering.

Change-Id: Ife249c6e8754aef23c144dbfdea5daaf7ed9f48a
Reviewed-on: https://boringssl-review.googlesource.com/25248
Reviewed-by: Adam Langley <agl@google.com>

crypto/fipsmodule/bn/montgomery.c

diff --git a/crypto/fipsmodule/bn/montgomery.c b/crypto/fipsmodule/bn/montgomery.c
index 6b562a0..1521a4d 100644
--- a/crypto/fipsmodule/bn/montgomery.c
+++ b/crypto/fipsmodule/bn/montgomery.c
@@ -126,10 +126,6 @@
 #define OPENSSL_BN_ASM_MONT
 #endif
 
-static int bn_mod_mul_montgomery_fallback(BIGNUM *r, const BIGNUM *a,
-                                          const BIGNUM *b,
-                                          const BN_MONT_CTX *mont, BN_CTX *ctx);
-
 
 BN_MONT_CTX *BN_MONT_CTX_new(void) {
   BN_MONT_CTX *ret = OPENSSL_malloc(sizeof(BN_MONT_CTX));
@@ -375,37 +371,6 @@
   return BN_from_montgomery(r, &mont->RR, mont, ctx);
 }
 
-int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
-                          const BN_MONT_CTX *mont, BN_CTX *ctx) {
-#if !defined(OPENSSL_BN_ASM_MONT)
-  return bn_mod_mul_montgomery_fallback(r, a, b, mont, ctx);
-#else
-  int num = mont->N.top;
-
-  // |bn_mul_mont| requires at least 128 bits of limbs, at least for x86.
-  if (num < (128 / BN_BITS2) ||
-      a->top != num ||
-      b->top != num) {
-    return bn_mod_mul_montgomery_fallback(r, a, b, mont, ctx);
-  }
-
-  if (!bn_wexpand(r, num)) {
-    return 0;
-  }
-  if (!bn_mul_mont(r->d, a->d, b->d, mont->N.d, mont->n0, num)) {
-    // The check above ensures this won't happen.
-    assert(0);
-    OPENSSL_PUT_ERROR(BN, ERR_R_INTERNAL_ERROR);
-    return 0;
-  }
-  r->neg = a->neg ^ b->neg;
-  r->top = num;
-  bn_correct_top(r);
-
-  return 1;
-#endif
-}
-
 static int bn_mod_mul_montgomery_fallback(BIGNUM *r, const BIGNUM *a,
                                           const BIGNUM *b,
                                           const BN_MONT_CTX *mont,
@@ -440,6 +405,34 @@
   return ret;
 }
 
+int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
+                          const BN_MONT_CTX *mont, BN_CTX *ctx) {
+#if defined(OPENSSL_BN_ASM_MONT)
+  // |bn_mul_mont| requires at least 128 bits of limbs, at least for x86.
+  int num = mont->N.top;
+  if (num >= (128 / BN_BITS2) &&
+      a->top == num &&
+      b->top == num) {
+    if (!bn_wexpand(r, num)) {
+      return 0;
+    }
+    if (!bn_mul_mont(r->d, a->d, b->d, mont->N.d, mont->n0, num)) {
+      // The check above ensures this won't happen.
+      assert(0);
+      OPENSSL_PUT_ERROR(BN, ERR_R_INTERNAL_ERROR);
+      return 0;
+    }
+    r->neg = a->neg ^ b->neg;
+    r->top = num;
+    bn_correct_top(r);
+
+    return 1;
+  }
+#endif
+
+  return bn_mod_mul_montgomery_fallback(r, a, b, mont, ctx);
+}
+
 int bn_to_montgomery_small(BN_ULONG *r, size_t num_r, const BN_ULONG *a,
                            size_t num_a, const BN_MONT_CTX *mont) {
   return bn_mod_mul_montgomery_small(r, num_r, a, num_a, mont->RR.d,