From d80e0dbd20bb8597afe92f770e39d20440557d1f Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sat, 25 Jun 2022 10:16:12 -0700
Subject: Demo for a coroutine-based step evaluator.

---
 aisa/aisa.h | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 72 insertions(+), 1 deletion(-)

(limited to 'aisa/aisa.h')

diff --git a/aisa/aisa.h b/aisa/aisa.h
index b570d6b..8cb302e 100644
--- a/aisa/aisa.h
+++ b/aisa/aisa.h
@@ -1,7 +1,78 @@
 #pragma once
 
+#include <coroutine>
+#include <cstdint>
+#include <iostream>
+#include <optional>
+#include <utility>
+#include <vector>
+
+#include "aisa/coroutine.h"
+
 namespace aisa {
 
-    void do_something();
+    using regnum_t = std::uint_fast64_t;
+    using regval_t = std::uint64_t;
+
+    template<typename CRTP> struct EvalState {
+        CRTP & crtp() noexcept { return static_cast<CRTP &>(*this); }
+        task<regval_t> async_load_reg(regnum_t rn)
+        {
+            while (true) {
+                if (auto rv = crtp().load_reg(rn); rv.has_value())
+                    co_return *rv;
+                co_await suspend();
+            }
+        }
+    };
+
+    struct Step {
+        const std::optional<std::pair<regnum_t, regval_t>> predicate;
+        const std::vector<regnum_t> source_regs;
+        const std::vector<regnum_t> destination_regs;
+
+        std::optional<regnum_t> predicate_reg() const
+        {
+            if (predicate.has_value())
+                return predicate->first;
+            return {};
+        }
+
+        std::optional<regnum_t> expected_predicate_val() const
+        {
+            if (predicate.has_value())
+                return predicate->second;
+            return {};
+        }
+
+        template<typename State> task<void> evaluate(State &state) const
+        {
+            if (predicate.has_value()) {
+                std::cout << "checking predicate...\n";
+                std::cout << "\texpect " << predicate->second << "\n";
+                regval_t pval = co_await state.async_load_reg(predicate->first);
+                std::cout << "\tgot " << pval << "\n";
+                if (pval != predicate->second) {
+                    std::cout << "\tpredicate skipped\n";
+                    co_return;
+                } else {
+                    std::cout << "\tpredicate not skipped\n";
+                }
+            }
+            std::cout << "reading sources...\n";
+            std::vector<regval_t> source_vals;
+            source_vals.reserve(source_regs.size());
+            for (unsigned int i = 0; i < source_regs.size(); ++i) {
+                std::cout << "\tgetting source " << i << "...\n";
+                source_vals.emplace_back(co_await state.async_load_reg(source_regs[i]));
+                std::cout << "\t\tgot " << source_vals.back() << "\n";
+            }
+            std::cout << "sources:";
+            for (unsigned int i = 0; i < source_regs.size(); ++i)
+                std::cout << " " << source_regs[i] << "=" << source_vals[i];
+            std::cout << "\n";
+            std::cout << "done with evaluate\n";
+        }
+    };
 
 }
-- 
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