From f95a85de0082010e4af83e26e99299d601bb48d6 Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Mon, 13 May 2024 00:04:44 +0200
Subject: Some work on CSR

---
 emulator/csr.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 emulator/csr.c

(limited to 'emulator/csr.c')

diff --git a/emulator/csr.c b/emulator/csr.c
new file mode 100644
index 0000000..d2527cf
--- /dev/null
+++ b/emulator/csr.c
@@ -0,0 +1,51 @@
+#include "emulator/csr.h"
+
+#include "emulator/hart.h"
+
+#include <stdbool.h>
+
+static inline uint8_t csr_priv(uint16_t id)
+{
+    return (id & 0x300) >> 8;
+}
+
+static inline bool csr_writable(uint16_t id)
+{
+    return (id & 0xC00) == 0xC00;
+}
+
+uint32_t csr_action(Hart* hart, uint16_t id, uint32_t value, enum CsrAction action)
+{
+    // @Todo exceptions (bad access (rw, level), non existent, etc)
+    if (id > 4096 || hart->csrs[id].action)
+    {
+        // @Todo
+        return 0;
+    }
+
+    if (action > CSR_R && csr_writable(id))
+    {
+        // @Todo
+        return 0;
+    }
+
+    if (csr_priv(id) > hart->priv)
+    {
+        // @Todo
+        return 0;
+    }
+
+    return hart->csrs[id].action(hart, value, action);
+}
+
+void csr_init_unpriv_counter_timer(Hart* hart);
+void csr_init_machine_trap_setup(Hart* hart);
+void csr_init_machine_information(Hart* hart);
+
+void csr_init(Hart* hart)
+{
+    csr_init_unpriv_counter_timer(hart);
+    csr_init_machine_trap_setup(hart);
+    csr_init_machine_information(hart);
+}
+
-- 
cgit