ext: rename libdummy_rocc by libcustomext

make library name general for multiple custom extension built in one
shared library.

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/customext/dummy_rocc.cc b/customext/dummy_rocc.cc
new file mode 100644
index 0000000..85ab7aa
--- /dev/null
+++ b/customext/dummy_rocc.cc
@@ -0,0 +1,47 @@
+#include "rocc.h"
+#include "mmu.h"
+#include <cstring>
+
+class dummy_rocc_t : public rocc_t
+{
+ public:
+  const char* name() { return "dummy_rocc"; }
+
+  reg_t custom0(rocc_insn_t insn, reg_t xs1, reg_t xs2)
+  {
+    reg_t prev_acc = acc[insn.rs2];
+
+    if (insn.rs2 >= num_acc)
+      illegal_instruction();
+
+    switch (insn.funct)
+    {
+      case 0: // acc <- xs1
+        acc[insn.rs2] = xs1;
+        break;
+      case 1: // xd <- acc (the only real work is the return statement below)
+        break;
+      case 2: // acc[rs2] <- Mem[xs1]
+        acc[insn.rs2] = p->get_mmu()->load_uint64(xs1);
+        break;
+      case 3: // acc[rs2] <- accX + xs1
+        acc[insn.rs2] += xs1;
+        break;
+      default:
+        illegal_instruction();
+    }
+
+    return prev_acc; // in all cases, xd <- previous value of acc[rs2]
+  }
+
+  dummy_rocc_t()
+  {
+    memset(acc, 0, sizeof(acc));
+  }
+
+ private:
+  static const int num_acc = 4;
+  reg_t acc[num_acc];
+};
+
+REGISTER_EXTENSION(dummy_rocc, []() { return new dummy_rocc_t; })