1 files changed, 64 insertions, 0 deletions
diff --git a/target/riscv/bitmanip_helper.c b/target/riscv/bitmanip_helper.c
new file mode 100644
index 0000000000..c625adaded
--- /dev/null
+++ b/target/riscv/bitmanip_helper.c
@@ -0,0 +1,64 @@
+/*
+ * RISC-V Bitmanip Extension Helpers for QEMU.
+ *
+ * Copyright (c) 2020 Kito Cheng, kito.cheng@sifive.com
+ * Copyright (c) 2020 Frank Chang, frank.chang@sifive.com
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/host-utils.h"
+#include "exec/exec-all.h"
+#include "exec/helper-proto.h"
+#include "tcg/tcg.h"
+
+static const uint64_t adjacent_masks[] = {
+    dup_const(MO_8, 0x55),
+    dup_const(MO_8, 0x33),
+    dup_const(MO_8, 0x0f),
+    dup_const(MO_16, 0xff),
+    dup_const(MO_32, 0xffff),
+    UINT32_MAX
+};
+
+static inline target_ulong do_swap(target_ulong x, uint64_t mask, int shift)
+{
+    return ((x & mask) << shift) | ((x & ~mask) >> shift);
+}
+
+static target_ulong do_grev(target_ulong rs1,
+                            target_ulong rs2,
+                            int bits)
+{
+    target_ulong x = rs1;
+    int i, shift;
+
+    for (i = 0, shift = 1; shift < bits; i++, shift <<= 1) {
+        if (rs2 & shift) {
+            x = do_swap(x, adjacent_masks[i], shift);
+        }
+    }
+
+    return x;
+}
+
+target_ulong HELPER(grev)(target_ulong rs1, target_ulong rs2)
+{
+    return do_grev(rs1, rs2, TARGET_LONG_BITS);
+}
+
+target_ulong HELPER(grevw)(target_ulong rs1, target_ulong rs2)
+{
+    return do_grev(rs1, rs2, 32);
+}