From 10563f5de9094d50ef26e3f81b47640fb990503f Mon Sep 17 00:00:00 2001
From: Donald Sebastian Leung <dl@m-labs.hk>
Date: Tue, 21 Jul 2020 16:13:52 +0800
Subject: [PATCH] Add LUI instruction for RV32I

---
 README.md         | 12 +++++++
 insns/insn_lui.py | 88 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)
 create mode 100644 insns/insn_lui.py

diff --git a/README.md b/README.md
index a01e72d..560e8f9 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,15 @@
 # riscv-formal-nmigen
 
 A port of [riscv-formal](https://github.com/SymbioticEDA/riscv-formal) to nMigen
+
+## Dependencies
+
+- [nMigen](https://github.com/m-labs/nmigen)
+
+## Build
+
+TODO
+
+## License
+
+See [LICENSE](./LICENSE)
diff --git a/insns/insn_lui.py b/insns/insn_lui.py
new file mode 100644
index 0000000..9d22f1c
--- /dev/null
+++ b/insns/insn_lui.py
@@ -0,0 +1,88 @@
+from nmigen import *
+
+class rvfi_insn_lui(Elaboratable):
+    def __init__(self, RISCV_FORMAL_ILEN=32, RISCV_FORMAL_XLEN=32, RISCV_FORMAL_CSR_MISA=False):
+        self.RISCV_FORMAL_ILEN = RISCV_FORMAL_ILEN
+        self.RISCV_FORMAL_XLEN = RISCV_FORMAL_XLEN
+        self.RISCV_FORMAL_CSR_MISA = RISCV_FORMAL_CSR_MISA
+        self.rvfi_valid = Signal(1)
+        self.rvfi_insn = Signal(self.RISCV_FORMAL_ILEN)
+        self.rvfi_pc_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_rs1_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_rs2_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_mem_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        if self.RISCV_FORMAL_CSR_MISA:
+            self.rvfi_csr_misa_rdata = Signal(self.RISCV_FORMAL_XLEN)
+            self.spec_csr_misa_rmask = Signal(self.RISCV_FORMAL_XLEN)
+        self.spec_valid = Signal(1)
+        self.spec_trap = Signal(1)
+        self.spec_rs1_addr = Signal(5)
+        self.spec_rs2_addr = Signal(5)
+        self.spec_rd_addr = Signal(5)
+        self.spec_rd_wdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.spec_pc_wdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.spec_mem_addr = Signal(self.RISCV_FORMAL_XLEN)
+        self.spec_mem_rmask = Signal(int(self.RISCV_FORMAL_XLEN // 8))
+        self.spec_mem_wmask = Signal(int(self.RISCV_FORMAL_XLEN // 8))
+        self.spec_mem_wdata = Signal(self.RISCV_FORMAL_XLEN)
+    def ports(self):
+        input_ports = [
+            self.rvfi_valid,
+            self.rvfi_insn,
+            self.rvfi_pc_rdata,
+            self.rvfi_rs1_rdata,
+            self.rvfi_rs2_rdata,
+            self.rvfi_mem_rdata
+        ]
+        output_ports = [
+            self.spec_valid,
+            self.spec_trap,
+            self.spec_rs1_addr,
+            self.spec_rs2_addr,
+            self.spec_rd_addr,
+            self.spec_rd_wdata,
+            self.spec_pc_wdata,
+            self.spec_mem_addr,
+            self.spec_mem_rmask,
+            self.spec_mem_wmask,
+            self.spec_mem_wdata
+        ]
+        if self.RISCV_FORMAL_CSR_MISA:
+            input_ports.append(self.rvfi_csr_misa_rdata)
+            output_ports.append(self.spec_csr_misa_rmask)
+        return input_ports + output_ports
+    def elaborate(self, platform):
+        m = Module()
+
+        # U-type instruction format
+        insn_padding = Signal(self.RISCV_FORMAL_ILEN)
+        m.d.comb += insn_padding.eq(self.rvfi_insn >> 32)
+        insn_imm = Signal(self.RISCV_FORMAL_XLEN)
+        m.d.comb += insn_imm.eq(Value.as_signed(self.rvfi_insn[12:32] << 12))
+        insn_rd = Signal(5)
+        m.d.comb += insn_rd.eq(self.rvfi_insn[7:12])
+        insn_opcode = Signal(7)
+        m.d.comb += insn_opcode.eq(self.rvfi_insn[:7])
+
+        misa_ok = Signal(1)
+        if self.RISCV_FORMAL_CSR_MISA:
+            m.d.comb += misa_ok.eq((self.rvfi_csr_misa_rdata & 0) == 0)
+            m.d.comb += self.spec_csr_misa_rmask.eq(0)
+        else:
+            m.d.comb += misa_ok.eq(1)
+
+        # LUI instruction
+        m.d.comb += self.spec_valid.eq(self.rvfi_valid & (~insn_padding) & (insn_opcode == 0b0110111))
+        m.d.comb += self.spec_rd_addr.eq(insn_rd)
+        m.d.comb += self.spec_rd_wdata.eq(Mux(self.spec_rd_addr, insn_imm, 0))
+        m.d.comb += self.spec_pc_wdata.eq(self.rvfi_pc_rdata + 4)
+        # default assignments
+        m.d.comb += self.spec_rs1_addr.eq(0)
+        m.d.comb += self.spec_rs2_addr.eq(0)
+        m.d.comb += self.spec_trap.eq(~misa_ok)
+        m.d.comb += self.spec_mem_addr.eq(0)
+        m.d.comb += self.spec_mem_rmask.eq(0)
+        m.d.comb += self.spec_mem_wmask.eq(0)
+        m.d.comb += self.spec_mem_wdata.eq(0)
+
+        return m