From b0324ec3b6e670b21a2369faa92483c381f0742e Mon Sep 17 00:00:00 2001
From: uvok
Date: Mon, 26 Jan 2026 20:34:08 +0100
Subject: eater: add countdown program

---
 eater_cpu/cpp/Veater_computer__main.cpp | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/eater_cpu/cpp/Veater_computer__main.cpp b/eater_cpu/cpp/Veater_computer__main.cpp
index d73e542..fe1a408 100644
--- a/eater_cpu/cpp/Veater_computer__main.cpp
+++ b/eater_cpu/cpp/Veater_computer__main.cpp
@@ -50,6 +50,26 @@ void load_program(const std::unique_ptr<Veater_computer> &topp) {
   topp->eater_computer->RAM->r_datastore[15] = 28;
 }
 
+void load_program_countdown(const std::unique_ptr<Veater_computer> &topp) {
+  std::vector<uint8_t> instructions
+      //
+      {// LDI 2
+       0x52,
+       // SUB 15
+       0x3f,
+       // JZ 4
+       0x84,
+       // JMP -> @0
+       0x61,
+       // HALT
+       0xf0};
+  std::copy(instructions.begin(), instructions.end(),
+            &topp->eater_computer->RAM->r_datastore[0]);
+
+  // Data @ 15
+  topp->eater_computer->RAM->r_datastore[15] = 1;
+}
+
 int main(int argc, char **argv, char **) {
   // Setup context, defaults, and parse command line
   Verilated::debug(0);
@@ -71,7 +91,7 @@ int main(int argc, char **argv, char **) {
   topp->auto_run_in = 1;
 
   // Load program
-  load_program(topp);
+  load_program_countdown(topp);
 
   simpc_ui_init();
 
-- 
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