From 3dbf23547ae72e08089be7bbecc224b074639c35 Mon Sep 17 00:00:00 2001
From: jbb01 <32650546+jbb01@users.noreply.github.com>
Date: Tue, 16 Sep 2025 20:03:15 +0200
Subject: [PATCH] [07_weird_assembly_machine] reorder main loop to make use of
 a faster implementation of f(g(x))

---
 res/07_weird_assembly_machine.sage   | 42 ++++++++++++++++++++++++++++
 src/bin/07_weird_assembly_machine.rs | 18 +++++++++---
 2 files changed, 56 insertions(+), 4 deletions(-)
 create mode 100644 res/07_weird_assembly_machine.sage

diff --git a/res/07_weird_assembly_machine.sage b/res/07_weird_assembly_machine.sage
new file mode 100644
index 0000000..303e242
--- /dev/null
+++ b/res/07_weird_assembly_machine.sage
@@ -0,0 +1,42 @@
+F = GF(2)
+R.<x> = PolynomialRing(F)
+S.<xi> = R.quotient_ring(x^64 + 1)
+T.<X> = PolynomialRing(S)
+Ti.<Xi> = T.quotient_ring(X^64 + 1)
+Tj.<Xj> = T.quotient_ring(X^64)
+
+def num_to_poly(num):
+    out = 0
+    i = 0
+    while num != 0:
+        if num % 2 == 1:
+            out += xi^i
+        i += 1
+        num //= 2
+    return out
+
+def poly_to_num(poly):
+    out = 0
+    for i in range(0, 64):
+        if poly[i] == 1:
+            out |= 1 << i
+    return out
+
+
+with open("./07_weird_assembly_machine.data") as f:
+    data = [int(line) for line in f.readlines() if line]
+
+f = reduce(lambda a, b: a * X + b, [num_to_poly(a) for a in data[:128]])
+g = reduce(lambda a, b: a * X + b, [num_to_poly(a) for a in data[128:]])
+
+fg = f(g)
+fgi = Ti([fg[i] for i in range(0, fg.degree())])
+fgj = Tj([fg[i] for i in range(0, fg.degree())])
+
+print("\n\n======= f(g(x)) =======")
+for i in reversed(range(0, 64)):
+    print(poly_to_num(fgi.lift()[i]))
+
+print("\n\n======= f(g(x)) =======")
+for i in reversed(range(0, 64)):
+    print(poly_to_num(fgj.lift()[i]))
\ No newline at end of file
diff --git a/src/bin/07_weird_assembly_machine.rs b/src/bin/07_weird_assembly_machine.rs
index 5ae1312..ef074e2 100644
--- a/src/bin/07_weird_assembly_machine.rs
+++ b/src/bin/07_weird_assembly_machine.rs
@@ -17,19 +17,24 @@ static DATA: LazyLock<Vec<u64>> = LazyLock::new(|| {
     data
 });
 
-const N: u64 = 10000045930000000;
-const X: u64 = 16195396392266746892;
+const N: u64 = 10000117800000000;
+const X: u64 = 5905739161907566595;
 
 fn main() {
     compute_async(|tx| {
         let mut n = N;
         let mut x = X;
         loop {
-            for _ in 0..1_000_000 {
+            n += 1;
+            x = sub(f(x), n);
+
+            for _ in 1..1_000_000 {
                 n += 1;
-                x = h(x, n);
+                x = sub(fg(x), n);
             }
 
+            x = g(x);
+
             tx.send((n, x)).unwrap();
         }
     });
@@ -47,6 +52,11 @@ fn g(x: u64) -> u64 {
     evaluate(x, &DATA[128..256])
 }
 
+/// Quickly computes [`f`](f)([`g`](g)(x)).
+fn fg(x: u64) -> u64 {
+    !x.rotate_left(17)
+}
+
 /// Evaluates a polynomial over `GF(2)[X] / (X^64 + 1)`
 fn evaluate(x: u64, data: &[u64]) -> u64 {
     let mut out = 0;