From bbaf58c9fd0f485266d86868dc35f1d2be3589cd Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sun, 26 Jun 2022 16:24:13 -0700
Subject: Significant changes, and a working "ISA" that just computes fib(n).

---
 aisa/simple-models.h | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 aisa/simple-models.h

(limited to 'aisa/simple-models.h')

diff --git a/aisa/simple-models.h b/aisa/simple-models.h
new file mode 100644
index 0000000..89e8752
--- /dev/null
+++ b/aisa/simple-models.h
@@ -0,0 +1,95 @@
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <cstring>
+#include <deque>
+#include <map>
+#include <memory>
+#include <optional>
+#include <utility>
+#include <vector>
+
+#include "aisa/aisa.h"
+
+namespace aisa {
+
+    template<unsigned int PAGE_BITS=10> struct PagedMem {
+        using page_t = std::array<byte_t, 1 << PAGE_BITS>;
+
+        static const addr_t PAGE_SIZE = 1 << PAGE_BITS;
+        static const addr_t PAGE_MASK = PAGE_SIZE - 1;
+
+        std::map<addr_t, page_t> pages;
+
+        bool fetch_mem(byte_t *bytes, addr_t addr, addr_t size)
+        {
+            if (size == 0)
+                return true;
+            auto page_base = addr >> PAGE_BITS;
+            auto page_offset = addr & PAGE_MASK;
+            auto size_here = std::min(size, PAGE_SIZE - page_offset);
+            if (auto page = pages.find(page_base); page != pages.end())
+                std::memcpy(bytes, page->second.data() + page_offset, size_here);
+            else
+                std::memset(bytes, 0, size_here);
+            return fetch_mem(bytes + size_here, addr + size_here, size - size_here);
+        }
+
+        bool store_mem(addr_t addr, const byte_t *bytes, addr_t size)
+        {
+            if (size == 0)
+                return true;
+            auto page_base = addr >> PAGE_BITS;
+            auto page_offset = addr & PAGE_MASK;
+            auto size_here = std::min(size, PAGE_SIZE - page_offset);
+            std::memcpy(pages[page_base].data() + page_offset, bytes, size_here);
+            return store_mem(addr + size_here, bytes + size_here, size - size_here);
+        }
+    };
+
+    struct TaskStack {
+        std::deque<std::unique_ptr<const Task>> tasks;
+
+        bool pop_task()
+        {
+            if (tasks.empty())
+                return false;
+            tasks.pop_back();
+            return true;
+        }
+
+        bool push_task(std::unique_ptr<const Task> &&task)
+        {
+            tasks.emplace_back(std::move(task));
+            return true;
+        }
+
+        std::optional<const Task *> top_task()
+        {
+            if (tasks.empty())
+                return {};
+            return tasks.back().get();
+        }
+    };
+
+    struct VectorRF {
+        std::vector<std::optional<regval_t>> rf;
+
+        std::optional<regval_t> load_reg(regnum_t rn) const
+        {
+            if (rf.size() <= rn)
+                return {};
+            return rf[rn];
+        }
+
+        bool store_reg(regnum_t rn, regval_t rv)
+        {
+            if (rf.size() <= rn)
+                rf.resize(rn + 1);
+            rf[rn] = rv;
+            return true;
+        }
+    };
+
+}
-- 
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