Add pippenger_wnaf ecmult_multi

Author: jonasnick

src/bench_ecmult.c

@@ -63,7 +63,7 @@ static void bench_ecmult(void* arg) {
     size_t iter;
 
     for (iter = 0; iter < iters; ++iter) {
-        secp256k1_ecmult_multi(&data->ctx->ecmult_ctx, data->scratch, &data->output[iter], data->includes_g ? &data->scalars[data->offset1] : NULL, bench_callback, arg, count - includes_g);
+        secp256k1_ecmult_multi_var(&data->ctx->ecmult_ctx, data->scratch, &data->output[iter], data->includes_g ? &data->scalars[data->offset1] : NULL, bench_callback, arg, count - includes_g);
         data->offset1 = (data->offset1 + count) % POINTS;
         data->offset2 = (data->offset2 + count - 1) % POINTS;
     }

src/ecmult.h

@@ -32,7 +32,12 @@ static void secp256k1_ecmult(const secp256k1_ecmult_context *ctx, secp256k1_gej
 
 typedef int (secp256k1_ecmult_multi_callback)(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data);
 
-/** Multi-multiply: R = inp_g_sc * G + sum_i ni * Ai. */
-static int secp256k1_ecmult_multi(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n);
+/**
+ * Multi-multiply: R = inp_g_sc * G + sum_i ni * Ai.
+ * Returns: 1 on success (including when inp_g_sc is NULL and n is 0)
+ *          0 if there is not enough scratch space for a single point or
+ *          callback returns 0
+ */
+static int secp256k1_ecmult_multi_var(const secp256k1_ecmult_context *ctx, secp256k1_scratch *scratch, secp256k1_gej *r, const secp256k1_scalar *inp_g_sc, secp256k1_ecmult_multi_callback cb, void *cbdata, size_t n);
 
 #endif /* SECP256K1_ECMULT_H */

src/ecmult_const_impl.h

@@ -12,13 +12,6 @@
 #include "ecmult_const.h"
 #include "ecmult_impl.h"
 
-#ifdef USE_ENDOMORPHISM
-    #define WNAF_BITS 128
-#else
-    #define WNAF_BITS 256
-#endif
-#define WNAF_SIZE(w) ((WNAF_BITS + (w) - 1) / (w))
-
 /* This is like `ECMULT_TABLE_GET_GE` but is constant time */
 #define ECMULT_CONST_TABLE_GET_GE(r,pre,n,w) do { \
     int m; \