self.sync += self.mepc.eq(0) # 32'hXXXXXXXX;
self.sync += self.mscratch.eq(0) # 32'hXXXXXXXX;
+
class Misa:
def __init__(self, comb, sync):
self.comb = comb
self.output_instruction = Signal(32, name="fetch_ouutput_instruction")
self.output_state = Signal(fetch_output_state,name="fetch_output_state")
+ def get_fetch_action(self, dc, load_store_misaligned, mi,
+ branch_taken, misaligned_jump_target,
+ csr_op_is_valid):
+ c = {}
+ c["default"] = self.action.eq(FA.default) # XXX should be 32'XXXXXXXX?
+ c[FOS.empty] = self.action.eq(FA.default)
+ c[FOS.trap] = self.action.eq(FA.ack_trap)
+
+ # illegal instruction -> error trap
+ i= If((dc.act & DA.trap_illegal_instruction) != 0,
+ self.action.eq(FA.error_trap)
+ )
+
+ # ecall / ebreak -> noerror trap
+ i = i.Elif((dc.act & DA.trap_ecall_ebreak) != 0,
+ self.action.eq(FA.noerror_trap))
+
+ # load/store: check alignment, check wait
+ i = i.Elif((dc.act & (DA.load | DA.store)) != 0,
+ If((load_store_misaligned | ~mi.rw_address_valid),
+ self.action.eq(FA.error_trap) # misaligned or invalid addr
+ ).Elif(mi.rw_wait,
+ self.action.eq(FA.wait) # wait
+ ).Else(
+ self.action.eq(FA.default) # ok
+ )
+ )
+
+ # fence
+ i = i.Elif((dc.act & DA.fence) != 0,
+ self.action.eq(FA.fence))
+
+ # branch -> misaligned=error, otherwise jump
+ i = i.Elif((dc.act & DA.branch) != 0,
+ If(misaligned_jump_target,
+ self.action.eq(FA.error_trap)
+ ).Else(
+ self.action.eq(FA.jump)
+ )
+ )
+
+ # jal/jalr -> misaligned=error, otherwise jump
+ i = i.Elif((dc.act & (DA.jal | DA.jalr)) != 0,
+ If(misaligned_jump_target,
+ self.action.eq(FA.error_trap)
+ ).Else(
+ self.action.eq(FA.jump)
+ )
+ )
+
+ # csr -> opvalid=ok, else error trap
+ i = i.Elif((dc.act & DA.csr) != 0,
+ If(csr_op_is_valid,
+ self.action.eq(FA.default)
+ ).Else(
+ self.action.eq(FA.error_trap)
+ )
+ )
+
+ c[FOS.valid] = i
+
+ return Case(self.output_state, c)
+
class CPU(Module):
"""
"""
def get_ls_misaligned(self, ls, funct3, load_store_address_low_2):
+ """ returns whether a load/store is misaligned
+ """
return Case(funct3[:2],
{ F3.sb: ls.eq(Constant(0)),
F3.sh: ls.eq(load_store_address_low_2[0] != 0),
for f in [F3.csrrc, F3.csrrci]: c[f] = ~written_value & previous_value
return Case(funct3, c)
- def get_fetch_action(self, ft, dc, load_store_misaligned, mi,
- branch_taken, misaligned_jump_target,
- csr_op_is_valid):
- c = {}
+ def handle_trap(self, m, ms, ft, dc, load_store_misaligned):
+ s = [ms.mpie.eq(ms.mie),
+ ms.mie.eq(0),
+ m.mepc.eq(Mux(ft.action == FA.noerror_trap,
+ ft.output_pc + 4,
+ ft.output_pc))]
+
+ # fetch action ack trap
+ i = If(ft.action == FA.ack_trap,
+ m.mcause.eq(cause_instruction_access_fault)
+ )
+
+ # ecall/ebreak
+ i = i.Elif((dc.act & DA.trap_ecall_ebreak) != 0,
+ m.mcause.eq(Mux(dc.immediate[0],
+ cause_machine_environment_call,
+ cause_breakpoint))
+ )
+
+ # load
+ i = i.Elif((dc.act & DA.load) != 0,
+ If(load_store_misaligned,
+ m.mcause.eq(cause_load_address_misaligned)
+ ).Else(
+ m.mcause.eq(cause_load_access_fault)
+ )
+ )
+
+ # store
+ i = i.Elif((dc.act & DA.store) != 0,
+ If(load_store_misaligned,
+ m.mcause.eq(cause_store_amo_address_misaligned)
+ ).Else(
+ m.mcause.eq(cause_store_amo_access_fault)
+ )
+ )
+
+ # jal/jalr -> misaligned=error, otherwise jump
+ i = i.Elif((dc.act & (DA.jal | DA.jalr | DA.branch)) != 0,
+ m.mcause.eq(cause_instruction_address_misaligned)
+ )
+
+ # defaults to illegal instruction
+ i = i.Else(m.mcause.eq(cause_illegal_instruction))
+
+ s.append(i)
+ return s
+
"""
- case(fetch_output_state)
- `fetch_output_state_empty:
- get_fetch_action = `fetch_action_default;
- `fetch_output_state_trap:
- get_fetch_action = `fetch_action_ack_trap;
- `fetch_output_state_valid: begin
- if((decode_action & `decode_action_trap_illegal_instruction) != 0) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else if((decode_action & `decode_action_trap_ecall_ebreak) != 0) begin
- get_fetch_action = `fetch_action_noerror_trap;
- end
- else if((decode_action & (`decode_action_load | `decode_action_store)) != 0) begin
- if(load_store_misaligned | ~memory_interface_rw_address_valid) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else if(memory_interface_rw_wait) begin
- get_fetch_action = `fetch_action_wait;
- end
- else begin
- get_fetch_action = `fetch_action_default;
- end
- end
- else if((decode_action & `decode_action_fence_i) != 0) begin
- get_fetch_action = `fetch_action_fence;
- end
- else if((decode_action & `decode_action_branch) != 0) begin
- if(branch_taken) begin
- if(misaligned_jump_target) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else begin
- get_fetch_action = `fetch_action_jump;
- end
- end
- else
- begin
- get_fetch_action = `fetch_action_default;
- end
- end
- else if((decode_action & (`decode_action_jal | `decode_action_jalr)) != 0) begin
- if(misaligned_jump_target) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else begin
- get_fetch_action = `fetch_action_jump;
- end
- end
- else if((decode_action & `decode_action_csr) != 0) begin
- if(csr_op_is_valid)
- get_fetch_action = `fetch_action_default;
- else
- get_fetch_action = `fetch_action_error_trap;
- end
- else begin
- get_fetch_action = `fetch_action_default;
- end
+ task handle_trap;
+ begin
+ mstatus_mpie = mstatus_mie;
+ mstatus_mie = 0;
+ mepc = (fetch_action == `fetch_action_noerror_trap) ? fetch_output_pc + 4 : fetch_output_pc;
+ if(fetch_action == `fetch_action_ack_trap) begin
+ mcause = `cause_instruction_access_fault;
+ end
+ else if((decode_action & `decode_action_trap_illegal_instruction) != 0) begin
+ mcause = `cause_illegal_instruction;
+ end
+ else if((decode_action & `decode_action_trap_ecall_ebreak) != 0) begin
+ mcause = decoder_immediate[0] ? `cause_machine_environment_call : `cause_breakpoint;
+ end
+ else if((decode_action & `decode_action_load) != 0) begin
+ if(load_store_misaligned)
+ mcause = `cause_load_address_misaligned;
+ else
+ mcause = `cause_load_access_fault;
+ end
+ else if((decode_action & `decode_action_store) != 0) begin
+ if(load_store_misaligned)
+ mcause = `cause_store_amo_address_misaligned;
+ else
+ mcause = `cause_store_amo_access_fault;
+ end
+ else if((decode_action & (`decode_action_branch | `decode_action_jal | `decode_action_jalr)) != 0) begin
+ mcause = `cause_instruction_address_misaligned;
+ end
+ else begin
+ mcause = `cause_illegal_instruction;
end
- default:
- get_fetch_action = 32'hXXXXXXXX;
- endcase
end
- endfunction
+ endtask
"""
def __init__(self):
self.comb += loaded_value.eq(Cat(b0, b1, b2))
self.comb += mi.rw_active.eq(~self.reset
- & (ft.output_state == fetch_output_state_valid)
+ & (ft.output_state == FOS.valid)
& ~load_store_misaligned
& ((dc.act & (DA.load | DA.store)) != 0))
csr_op_is_valid = Signal()
+ self.comb += ft.get_fetch_action(dc, load_store_misaligned, mi,
+ branch_taken, misaligned_jump_target,
+ csr_op_is_valid)
+
+ #self.comb += self.handle_trap(m, mstatus, ft, dc, load_store_misaligned)
+
if __name__ == "__main__":
example = CPU()
print(verilog.convert(example,
"""
- function `fetch_action get_fetch_action(
- input `fetch_output_state fetch_output_state,
- input `decode_action decode_action,
- input load_store_misaligned,
- input memory_interface_rw_address_valid,
- input memory_interface_rw_wait,
- input branch_taken,
- input misaligned_jump_target,
- input csr_op_is_valid
- );
- begin
- case(fetch_output_state)
- `fetch_output_state_empty:
- get_fetch_action = `fetch_action_default;
- `fetch_output_state_trap:
- get_fetch_action = `fetch_action_ack_trap;
- `fetch_output_state_valid: begin
- if((decode_action & `decode_action_trap_illegal_instruction) != 0) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else if((decode_action & `decode_action_trap_ecall_ebreak) != 0) begin
- get_fetch_action = `fetch_action_noerror_trap;
- end
- else if((decode_action & (`decode_action_load | `decode_action_store)) != 0) begin
- if(load_store_misaligned | ~memory_interface_rw_address_valid) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else if(memory_interface_rw_wait) begin
- get_fetch_action = `fetch_action_wait;
- end
- else begin
- get_fetch_action = `fetch_action_default;
- end
- end
- else if((decode_action & `decode_action_fence_i) != 0) begin
- get_fetch_action = `fetch_action_fence;
- end
- else if((decode_action & `decode_action_branch) != 0) begin
- if(branch_taken) begin
- if(misaligned_jump_target) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else begin
- get_fetch_action = `fetch_action_jump;
- end
- end
- else
- begin
- get_fetch_action = `fetch_action_default;
- end
- end
- else if((decode_action & (`decode_action_jal | `decode_action_jalr)) != 0) begin
- if(misaligned_jump_target) begin
- get_fetch_action = `fetch_action_error_trap;
- end
- else begin
- get_fetch_action = `fetch_action_jump;
- end
- end
- else if((decode_action & `decode_action_csr) != 0) begin
- if(csr_op_is_valid)
- get_fetch_action = `fetch_action_default;
- else
- get_fetch_action = `fetch_action_error_trap;
- end
- else begin
- get_fetch_action = `fetch_action_default;
- end
- end
- default:
- get_fetch_action = 32'hXXXXXXXX;
- endcase
- end
- endfunction
-
- assign fetch_action = get_fetch_action(
- fetch_output_state,
- decode_action,
- load_store_misaligned,
- memory_interface_rw_address_valid,
- memory_interface_rw_wait,
- branch_taken,
- misaligned_jump_target,
- csr_op_is_valid
- );
-
- task handle_trap;
- begin
- mstatus_mpie = mstatus_mie;
- mstatus_mie = 0;
- mepc = (fetch_action == `fetch_action_noerror_trap) ? fetch_output_pc + 4 : fetch_output_pc;
- if(fetch_action == `fetch_action_ack_trap) begin
- mcause = `cause_instruction_access_fault;
- end
- else if((decode_action & `decode_action_trap_illegal_instruction) != 0) begin
- mcause = `cause_illegal_instruction;
- end
- else if((decode_action & `decode_action_trap_ecall_ebreak) != 0) begin
- mcause = decoder_immediate[0] ? `cause_machine_environment_call : `cause_breakpoint;
- end
- else if((decode_action & `decode_action_load) != 0) begin
- if(load_store_misaligned)
- mcause = `cause_load_address_misaligned;
- else
- mcause = `cause_load_access_fault;
- end
- else if((decode_action & `decode_action_store) != 0) begin
- if(load_store_misaligned)
- mcause = `cause_store_amo_address_misaligned;
- else
- mcause = `cause_store_amo_access_fault;
- end
- else if((decode_action & (`decode_action_branch | `decode_action_jal | `decode_action_jalr)) != 0) begin
- mcause = `cause_instruction_address_misaligned;
- end
- else begin
- mcause = `cause_illegal_instruction;
- end
- end
- endtask
-
wire [11:0] csr_number = decoder_immediate;
wire [31:0] csr_input_value = decoder_funct3[2] ? decoder_rs1 : register_rs1;
wire csr_reads = decoder_funct3[1] | (decoder_rd != 0);
projects / rv32.git / blobdiff