Remove unused secp256k1_scalar_shr_int

Author: sipa

src/scalar.h

@@ -54,10 +54,6 @@ static void secp256k1_scalar_cadd_bit(secp256k1_scalar *r, unsigned int bit, int
 /** Multiply two scalars (modulo the group order). */
 static void secp256k1_scalar_mul(secp256k1_scalar *r, const secp256k1_scalar *a, const secp256k1_scalar *b);
 
-/** Shift a scalar right by some amount strictly between 0 and 16, returning
- *  the low bits that were shifted off */
-static int secp256k1_scalar_shr_int(secp256k1_scalar *r, int n);
-
 /** Compute the inverse of a scalar (modulo the group order). */
 static void secp256k1_scalar_inverse(secp256k1_scalar *r, const secp256k1_scalar *a);
 

src/scalar_4x64_impl.h

@@ -787,18 +787,6 @@ static void secp256k1_scalar_mul(secp256k1_scalar *r, const secp256k1_scalar *a,
     secp256k1_scalar_reduce_512(r, l);
 }
 
-static int secp256k1_scalar_shr_int(secp256k1_scalar *r, int n) {
-    int ret;
-    VERIFY_CHECK(n > 0);
-    VERIFY_CHECK(n < 16);
-    ret = r->d[0] & ((1 << n) - 1);
-    r->d[0] = (r->d[0] >> n) + (r->d[1] << (64 - n));
-    r->d[1] = (r->d[1] >> n) + (r->d[2] << (64 - n));
-    r->d[2] = (r->d[2] >> n) + (r->d[3] << (64 - n));
-    r->d[3] = (r->d[3] >> n);
-    return ret;
-}
-
 static void secp256k1_scalar_split_128(secp256k1_scalar *r1, secp256k1_scalar *r2, const secp256k1_scalar *k) {
     r1->d[0] = k->d[0];
     r1->d[1] = k->d[1];

src/scalar_8x32_impl.h

@@ -600,22 +600,6 @@ static void secp256k1_scalar_mul(secp256k1_scalar *r, const secp256k1_scalar *a,
     secp256k1_scalar_reduce_512(r, l);
 }
 
-static int secp256k1_scalar_shr_int(secp256k1_scalar *r, int n) {
-    int ret;
-    VERIFY_CHECK(n > 0);
-    VERIFY_CHECK(n < 16);
-    ret = r->d[0] & ((1 << n) - 1);
-    r->d[0] = (r->d[0] >> n) + (r->d[1] << (32 - n));
-    r->d[1] = (r->d[1] >> n) + (r->d[2] << (32 - n));
-    r->d[2] = (r->d[2] >> n) + (r->d[3] << (32 - n));
-    r->d[3] = (r->d[3] >> n) + (r->d[4] << (32 - n));
-    r->d[4] = (r->d[4] >> n) + (r->d[5] << (32 - n));
-    r->d[5] = (r->d[5] >> n) + (r->d[6] << (32 - n));
-    r->d[6] = (r->d[6] >> n) + (r->d[7] << (32 - n));
-    r->d[7] = (r->d[7] >> n);
-    return ret;
-}
-
 static void secp256k1_scalar_split_128(secp256k1_scalar *r1, secp256k1_scalar *r2, const secp256k1_scalar *k) {
     r1->d[0] = k->d[0];
     r1->d[1] = k->d[1];

src/scalar_low_impl.h

@@ -95,15 +95,6 @@ static void secp256k1_scalar_mul(secp256k1_scalar *r, const secp256k1_scalar *a,
     *r = (*a * *b) % EXHAUSTIVE_TEST_ORDER;
 }
 
-static int secp256k1_scalar_shr_int(secp256k1_scalar *r, int n) {
-    int ret;
-    VERIFY_CHECK(n > 0);
-    VERIFY_CHECK(n < 16);
-    ret = *r & ((1 << n) - 1);
-    *r >>= n;
-    return ret;
-}
-
 static void secp256k1_scalar_split_128(secp256k1_scalar *r1, secp256k1_scalar *r2, const secp256k1_scalar *a) {
     *r1 = *a;
     *r2 = 0;

src/tests.c

@@ -2054,20 +2054,6 @@ void scalar_test(void) {
         CHECK(secp256k1_scalar_eq(&n, &s));
     }
 
-    {
-        /* test secp256k1_scalar_shr_int */
-        secp256k1_scalar r;
-        int i;
-        random_scalar_order_test(&r);
-        for (i = 0; i < 100; ++i) {
-            int low;
-            int shift = 1 + secp256k1_testrand_int(15);
-            int expected = r.d[0] % (1 << shift);
-            low = secp256k1_scalar_shr_int(&r, shift);
-            CHECK(expected == low);
-        }
-    }
-
     {
         /* Test commutativity of add. */
         secp256k1_scalar r1, r2;
@@ -5014,13 +5000,12 @@ void test_fixed_wnaf(const secp256k1_scalar *number, int w) {
     int wnaf[256] = {0};
     int i;
     int skew;
-    secp256k1_scalar num = *number;
+    secp256k1_scalar num, unused;
 
     secp256k1_scalar_set_int(&x, 0);
     secp256k1_scalar_set_int(&shift, 1 << w);
-    for (i = 0; i < 16; ++i) {
-        secp256k1_scalar_shr_int(&num, 8);
-    }
+    /* Make num a 128-bit scalar. */
+    secp256k1_scalar_split_128(&num, &unused, number);
     skew = secp256k1_wnaf_fixed(wnaf, &num, w);
 
     for (i = WNAF_SIZE(w)-1; i >= 0; --i) {