from insn_R import *

class rvfi_insn_sra(rvfi_insn_R):
    def __init__(self):
        super(rvfi_insn_sra, self).__init__()
    def ports(self):
        return super(rvfi_insn_sra, self).ports()
    def elaborate(self, platform):
        m = super(rvfi_insn_sra, self).elaborate(platform)

        # SRA instruction
        shamt = Signal(6)
        m.d.comb += shamt.eq(self.rvfi_rs2_rdata[:5])
        result = Signal(32)
        m.d.comb += result.eq((self.rvfi_rs1_rdata >> shamt) | (-(self.rvfi_rs1_rdata < 0) << (32 - shamt))) # https://stackoverflow.com/a/25207042
        m.d.comb += self.spec_valid.eq(self.rvfi_valid & (~self.insn_padding) & (self.insn_funct7 == 0b0100000) & (self.insn_funct3 == 0b101) & (self.insn_opcode == 0b0110011))
        m.d.comb += self.spec_rs1_addr.eq(self.insn_rs1)
        m.d.comb += self.spec_rs2_addr.eq(self.insn_rs2)
        m.d.comb += self.spec_rd_addr.eq(self.insn_rd)
        m.d.comb += self.spec_rd_wdata.eq(Mux(self.spec_rd_addr, result, 0))
        m.d.comb += self.spec_pc_wdata.eq(self.rvfi_pc_rdata + 4)

        return m