Initial commit.

2 files changed, 111 insertions, 0 deletions

diff --git a/memory/dram.h b/memory/dram.h
new file mode 100644
index 0000000..f59c7a6
--- /dev/null
+++ b/memory/dram.h
@@ -0,0 +1,96 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+#include <cstring>
+#include <istream>
+#include <map>
+#include <string>
+#include <utility>
+
+#include "memory/line.h"
+
+namespace memory {
+    struct dram : public infra::sim {
+        static constexpr std::uint64_t PAGE_LINES_LOG2 = 20 - LINE_BYTES_LOG2;
+        static constexpr std::uint64_t PAGE_LINES = 1 << PAGE_LINES_LOG2;
+        static constexpr std::uint64_t PAGE_LINE_OFFSET_MASK = PAGE_LINES - 1;
+        static constexpr std::uint64_t PAGE_BYTES_LOG2 = PAGE_LINES_LOG2 + LINE_BYTES_LOG2;
+        static constexpr std::uint64_t PAGE_BYTES = 1 << PAGE_BYTES_LOG2;
+        static constexpr std::uint64_t PAGE_BYTE_OFFSET_MASK = PAGE_BYTES - 1;
+
+        typedef std::array<line, PAGE_LINES> page;
+
+        std::map<std::uint64_t, page> image;
+
+        struct response {
+            infra::transaction transaction;
+            std::uint64_t line_address;
+            line data;
+        };
+
+        struct command {
+            infra::transaction transaction;
+            std::uint64_t line_address;
+            line data;
+            std::array<bool, LINE_BYTES> mask;
+            bool write = false;
+            infra::port<response> *responsep = nullptr;
+        };
+
+        infra::port<command> commandp;
+
+        void clock() {
+            if (commandp.can_read()) {
+                const auto &c = commandp.peek();
+                if (!c.responsep || c.responsep->can_write()) {
+                    auto page_address = c.line_address >> PAGE_LINES_LOG2;
+                    auto page_line = c.line_address & PAGE_LINE_OFFSET_MASK;
+                    if (c.write) {
+                        pte(c.transaction, "s", fmt::format("store {:x}-{:x}", page_address, page_line));
+                        if (c.responsep) {
+                            response r;
+                            r.transaction = c.transaction;
+                            r.line_address = c.line_address;
+                            r.data = c.data;
+                            c.responsep->write(std::move(r));
+                        }
+                        auto [p, emplaced] = image.try_emplace(page_address);
+                        if (emplaced)
+                            for (unsigned int i = 0; i < PAGE_LINES; ++i)
+                                p->second[i].fill(0);
+                        auto &l = p->second[page_line];
+                        for (unsigned int i = 0; i < LINE_BYTES; ++i)
+                            if (c.mask[i])
+                                l[i] = c.data[i];
+                    } else {
+                        pte(c.transaction, "f", fmt::format("fill {:x}-{:x}", page_address, page_line));
+                        if (c.responsep) {
+                            response r;
+                            r.transaction = c.transaction;
+                            r.line_address = c.line_address;
+                            if (auto p = image.find(page_address); p != image.end())
+                                r.data = p->second[page_line];
+                            else
+                                r.data.fill(0);
+                            c.responsep->write(std::move(r));
+                        }
+                    }
+                    commandp.discard();
+                }
+            }
+        }
+
+        void load(std::istream &fh) {
+            for (unsigned int page = 0; ; ++page) {
+                auto [p, emplaced] = image.try_emplace(page);
+                if (emplaced)
+                    for (unsigned int i = 0; i < PAGE_LINES; ++i)
+                        p->second[i].fill(0);
+                for (unsigned int line = 0; line < PAGE_LINES; ++line)
+                    if (!fh.read(reinterpret_cast<char *>(p->second[line].data()), LINE_BYTES))
+                        return;
+            }
+        }
+    };
+}
diff --git a/memory/line.h b/memory/line.h
new file mode 100644
index 0000000..3377ec8
--- /dev/null
+++ b/memory/line.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+
+#include "infra/port.h"
+#include "infra/sim.h"
+
+namespace memory {
+    constexpr std::uint64_t LINE_BYTES_LOG2 = 4;
+    constexpr std::uint64_t LINE_BYTES = 1 << LINE_BYTES_LOG2;
+    constexpr std::uint64_t LINE_BYTE_OFFSET_MASK = LINE_BYTES - 1;
+
+    typedef std::array<std::uint8_t, LINE_BYTES> line;
+}