dep: Add biscuit and riscv-disas

dep/biscuit/src/cpuinfo.cpp

@@ -0,0 +1,39 @@
+// Copyright (c), 2022, KNS Group LLC (YADRO)
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+#include <biscuit/cpuinfo.hpp>
+
+namespace biscuit {
+
+bool CPUInfo::Has(RISCVExtension extension) const {
+#if defined(__linux__) && defined(__riscv)
+    const static uint64_t features = getauxval(AT_HWCAP) & (
+                            COMPAT_HWCAP_ISA_I |
+                            COMPAT_HWCAP_ISA_M |
+                            COMPAT_HWCAP_ISA_A |
+                            COMPAT_HWCAP_ISA_F |
+                            COMPAT_HWCAP_ISA_D |
+                            COMPAT_HWCAP_ISA_C |
+                            COMPAT_HWCAP_ISA_V
+    );
+#else
+    const static uint64_t features = 0;
+#endif
+
+    return (features & static_cast<uint64_t>(extension)) != 0;
+}
+
+uint32_t CPUInfo::GetVlenb() const {
+    if(Has(RISCVExtension::V)) {
+        static CSRReader<CSR::VLenb> csrReader;
+        const static auto getVLEN = csrReader.GetCode<uint32_t (*)()>();
+        return getVLEN();
+    }
+
+    return 0;
+}
+
+} // namespace biscuit