From d43d7caf15a01dd9c2ef1d9e975df3ef7c4e9204 Mon Sep 17 00:00:00 2001
From: Clyne Sullivan <clyne@bitgloo.com>
Date: Fri, 27 Sep 2024 06:02:49 -0400
Subject: wip: initial commit

---
 tasking.cpp | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 tasking.cpp

(limited to 'tasking.cpp')

diff --git a/tasking.cpp b/tasking.cpp
new file mode 100644
index 0000000..9e2cd49
--- /dev/null
+++ b/tasking.cpp
@@ -0,0 +1,60 @@
+#include "tasking.hpp"
+
+#include <array>
+
+struct Task
+{
+    Registers regs;
+    bool valid = false;
+};
+
+static std::array<Task, 4> tasks;
+static int current = -1;
+
+void schedule(Registers& regs)
+{
+    if (current < 0)
+        return;
+
+    tasks[current].regs = regs;
+
+    do {
+        if (++current >= tasks.size())
+            current = 0;
+    } while (!tasks[current].valid);
+
+    regs = tasks[current].regs;
+}
+
+void tasking_initialize()
+{
+    tasks[0].valid = true;
+    current = 0;
+    asm volatile("int $0x20");
+}
+
+bool tasking_spawn(void (*entry)(), unsigned ssize)
+{
+    int i = -1;
+    for (i = 0; i < tasks.size(); ++i) {
+        if (!tasks[i].valid)
+            break;
+    }
+
+    if (i < 0)
+        return false;
+
+    tasks[i] = Task();
+
+    auto& r = tasks[i].regs;
+    auto stack = reinterpret_cast<std::uint32_t>(new std::uint8_t[ssize]);
+    r.ebp = stack + ssize;
+    r.esp = r.ebp;
+    r.eip = reinterpret_cast<std::uint32_t>(entry);
+    r.cs = 0x8;
+    r.eflags = tasks[current].regs.eflags;
+
+    tasks[i].valid = true;
+    return true;
+}
+
-- 
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