Some work on CSR

emulator/bits.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <stdint.h>
+
+static inline uint32_t sign_extend(uint32_t word, uint32_t size)
+{
+    const uint32_t mask = 1U << (size - 1);
+    return (word ^ mask) - mask;
+}
+
+static inline uint64_t sign_extend_64(uint64_t word, uint32_t size)
+{
+    const uint64_t mask = 1ULL << (size - 1);
+    return (word ^ mask) - mask;
+}