From fce4f1be23615d7c89c5f9aaa817a60258d1bf19 Mon Sep 17 00:00:00 2001
From: Arvid Norberg <arvid@libtorrent.org>
Date: Thu, 6 Oct 2022 21:38:51 +0200
Subject: [PATCH] Updating intermediates generation, and fix some const
 correctness (#132)

Co-authored-by: Raphael Toledo <contact@raphael-toledo.com>
---
 src/nucomp.h      |  4 ++--
 src/prover_slow.h | 18 ++++++++++++------
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/nucomp.h b/src/nucomp.h
index 9437e376..aef14a47 100644
--- a/src/nucomp.h
+++ b/src/nucomp.h
@@ -51,7 +51,7 @@ typedef struct qfb
 typedef qfb qfb_t[1];
 
 // From Antic using Flint (works!)
-void qfb_nucomp(qfb_t r, const qfb_t f, const qfb_t g, mpz_t& D, mpz_t& L)
+void qfb_nucomp(qfb_t r, const qfb_t f, const qfb_t g, mpz_t const& D, mpz_t const& L)
 {
    mpz_t a1, a2, c2, ca, cb, cc, k, s, sp, ss, m, t, u2, v1, v2;
 
@@ -192,7 +192,7 @@ void qfb_nucomp(qfb_t r, const qfb_t f, const qfb_t g, mpz_t& D, mpz_t& L)
 }
 
 // a = b * c
-void nucomp_form(form &a, form &b, form &c, integer &D, integer &L) {
+void nucomp_form(form &a, form const& b, form const& c, integer const& D, integer const& L) {
     qfb fr, fr2, fr3;
 
     *fr.a = *a.a.impl;
diff --git a/src/prover_slow.h b/src/prover_slow.h
index 2cb18e84..de3f5108 100644
--- a/src/prover_slow.h
+++ b/src/prover_slow.h
@@ -30,7 +30,7 @@ uint64_t GetBlock(uint64_t i, uint64_t k, uint64_t T, integer& B) {
 
 form GenerateWesolowski(form &y, form &x_init,
                         integer &D, PulmarkReducer& reducer,
-                        std::vector<form>& intermediates,
+                        std::vector<form> const& intermediates,
                         uint64_t num_iterations,
                         uint64_t k, uint64_t l) {
     integer B = GetB(D, x_init, y);
@@ -82,20 +82,26 @@ std::vector<uint8_t> ProveSlow(integer& D, form& x, uint64_t num_iterations) {
     integer L = root(-D, 4);
     PulmarkReducer reducer;
     form y = form::from_abd(x.a, x.b, D);
-    std::vector<form> intermediates;
-    int k, l;
     int d_bits = D.num_bits();
 
+    int k, l;
     ApproximateParameters(num_iterations, l, k);
     if (k <= 0) k = 1;
     if (l <= 0) l = 1;
-    for (int i = 0; i < num_iterations; i++) {
-        if (i % (k * l) == 0) {
-            intermediates.push_back(y);
+    int const kl = k * l;
+
+    uint64_t const size_vec = (num_iterations + kl - 1) / kl;
+    std::vector<form> intermediates(size_vec);
+    form* cursor = intermediates.data();
+    for (uint64_t i = 0; i < num_iterations; i++) {
+        if (i % kl == 0) {
+            *cursor = y;
+            ++cursor;
         }
         nudupl_form(y, y, D, L);
         reducer.reduce(y);
     }
+
     form proof = GenerateWesolowski(y, x, D, reducer, intermediates, num_iterations, k, l);
     std::vector<uint8_t> result = SerializeForm(y, d_bits);
     std::vector<uint8_t> proof_bytes = SerializeForm(proof, d_bits);