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-rw-r--r--hdl/core.py157
1 files changed, 147 insertions, 10 deletions
diff --git a/hdl/core.py b/hdl/core.py
index 506de96..9355bf3 100644
--- a/hdl/core.py
+++ b/hdl/core.py
@@ -1,6 +1,7 @@
+from ast import Del
from curses.ascii import SI
from multiprocessing import dummy
-from tkinter import S
+from tkinter import S, Y
from amaranth import *
from amaranth.sim import Simulator, Settle, Delay
from enum import Enum, unique
@@ -9,7 +10,7 @@ from utils import cmd
class Reg(Elaboratable):
- def __init__(self):
+ def __init__(self, sim=False): # sim is only for modularity, does nothing for this
# enable write
self.wr_en = Signal(1)
@@ -49,7 +50,8 @@ class Reg(Elaboratable):
# internal signals
self._user_mode = Signal(1)
- self._sp_write = Signal(1)
+ self._sp_inc_dec = Signal(1)
+ self._wr_alu_flg = Signal(1)
self.zx = Signal(32) #0
self.ax = Signal(32) #1
@@ -110,26 +112,39 @@ class Reg(Elaboratable):
m.d.sync += self.sp.eq(self.cs1)
m.d.sync += self.flg.eq(self.cs2)
- m.d.comb += self._sp_write.eq(0)
+ m.d.comb += self._sp_inc_dec.eq(0)
+ m.d.comb += self._wr_alu_flg.eq(1)
# writeback setup
with m.If(self.wr_en):
with m.Switch(self.rd_addr):
with m.Case(self.zx.idx): # do not write to zero register
pass
+
with m.Case(self.ip.idx): #do not directly write to ip register
pass
+
with m.Case(self.flg.idx):
# mask top half of register to prevent writing to flags in user mode
- m.d.sync += self.flg.eq(self.rd & Cat(Const(0xFFFF, 16), Repl(~self._user_mode, 16)))
+ with m.If(~self._user_mode):
+ m.d.sync += self.flg.eq(self.rd) # system mode, full control
+ with m.Else():
+ m.d.sync += self.flg.eq(Cat(self.rd[:16], self.flg[16:])) # usermode can only effect lower 16 bits
+
+ # don't update flags from alu
+ m.d.comb += self._wr_alu_flg.eq(0)
+
with m.Case(self.sp.idx):
- m.d.comb += self._sp_write.eq(1)
+ m.d.comb += self._sp_inc_dec.eq(1)
m.d.sync += self.sp.eq(self.rd)
+
with m.Case():
- m.d.sync += self.flg.eq(Cat(self.alu_flgs, self.flg[len(self.alu_flgs):])) # update flags if register is not being written to
m.d.sync += self.reg_arr[self.rd_addr].eq(self.rd)
- with m.If(~self._sp_write & self.stack_instr):
+ with m.If(self._wr_alu_flg):
+ m.d.sync += self.flg.eq(Cat(self.alu_flgs, self.flg[len(self.alu_flgs):])) # update flags if register is not being written to
+
+ with m.If(~self._sp_inc_dec & self.stack_instr):
with m.If(self.stack_down_up):
m.d.sync += self.sp.eq(self.sp - 1)
with m.Else():
@@ -151,6 +166,128 @@ class Reg(Elaboratable):
return m
+def test_reg(filename="reg.vcd"):
+ dut = Reg(sim=True)
+
+ def init():
+ for i in range(16):
+ yield dut.reg_arr[i].eq(i)
+ yield Settle()
+
+ def step():
+ yield Settle() # settle comb logic before clock
+ yield # clock edge
+ yield Settle() # settle comb logic after clock
+ yield Delay(5e-7) # used for debugging, change values on neg edge of clock
+
+ def proc1():
+ yield from init()
+
+ # test combinational output
+ for i in range(16):
+ yield dut.rs1_addr.eq(i)
+ yield Settle()
+ assert (yield dut.rs1) == i, f'ERROR reading {dut.reg_arr[i].name} != {i}'
+ for i in range(16):
+ yield dut.rs2_addr.eq(i)
+ yield Settle()
+ assert (yield dut.rs2) == i, f'ERROR reading {dut.reg_arr[i].name} != {i}'
+
+ # test writeback with writeback disabled
+ yield from init()
+ for i in range(16):
+ yield dut.rd_addr.eq(i)
+ yield dut.rd.eq(i + 1)
+ yield from step()
+ if (i != dut.ip.idx) and (i != dut.flg.idx): # flag gets update by the alu
+ assert (yield dut.reg_arr[i]) == i, f'ERROR writing to {dut.reg_arr[i].name} != {i}'
+
+ # test writeback with writeback enabled
+ for i in range(16):
+ yield from init()
+ yield dut.wr_en.eq(1)
+ yield dut.rd_addr.eq(i)
+ yield dut.rd.eq(i - 1)
+ yield from step()
+ if (i != dut.zx.idx) and (i != dut.ip.idx):
+ assert (yield dut.reg_arr[i]) == i-1, f'ERROR writing to {dut.reg_arr[i].name} != {i-1}'
+ elif i == dut.zx.idx:
+ assert (yield dut.zx) == 0, f'ERROR {dut.zx.name} != 0'
+ elif i == dut.ip.idx:
+ # ip should be incremented and not written to
+ assert (yield dut.reg_arr[i]) == i+1, f'ERROR {dut.ip.name} != {i + 1} should not be able to be directly written to'
+
+ yield dut.wr_en.eq(0)
+
+ # test flag register security
+ yield dut.flg.eq(0)
+ yield dut.flg.user_mode.eq(1)
+ yield dut.flg[15].eq(1)
+ yield dut.flg[31].eq(1)
+ yield dut.rs1_addr.eq(dut.flg.idx)
+ yield Settle()
+ assert (yield dut.rs1) == 0x00008000, f'ERROR: able to read upper 16 bits of flg reg in user mode'
+
+ # test flag register security
+ yield dut.flg.eq(0)
+ yield dut.wr_en.eq(1)
+ yield dut.flg.user_mode.eq(1)
+ yield dut.flg[15].eq(1)
+ yield dut.flg[31].eq(1)
+ yield dut.rd_addr.eq(dut.flg.idx)
+ yield dut.rd.eq(0xABCD5789)
+ yield from step()
+ assert (yield dut.flg) == (0x80020000 | 0x5789), f'ERROR: able to write to upper 16 bits of flg reg in user mode'
+
+ yield dut.flg.eq(0)
+ yield dut.flg.user_mode.eq(0)
+ yield dut.flg[15].eq(1)
+ yield dut.flg[31].eq(1)
+ yield dut.rs1_addr.eq(dut.flg.idx)
+ yield Settle()
+ assert (yield dut.rs1) == 0x80008000, f'ERROR: able to read all bits of flg reg in system mode'
+
+ yield dut.flg.eq(0)
+ yield dut.wr_en.eq(1)
+ yield dut.flg.user_mode.eq(0)
+ yield dut.flg[15].eq(1)
+ yield dut.flg[31].eq(1)
+ yield dut.rd_addr.eq(dut.flg.idx)
+ yield dut.rd.eq(0xABCD5789)
+ yield from step()
+ assert (yield dut.flg) == (0xABCD5789), f'ERROR: unamble to write to all bits in supervisor mode'
+
+ # make sure not to write alu flags when directly writing to flg register
+ yield dut.flg.eq(0)
+ yield dut.alu_flgs.eq(Repl(1, dut.alu_flgs.width))
+ yield dut.wr_en.eq(1)
+ yield dut.flg.user_mode.eq(0)
+ yield dut.flg[15].eq(1)
+ yield dut.flg[31].eq(1)
+ yield dut.rd_addr.eq(dut.flg.idx)
+ yield dut.rd.eq(0xFFFF0000)
+ yield from step()
+ assert (yield dut.flg) == (0xFFFF0000), f'ERROR: alu status should not be to flag'
+
+ # check to make sure alu is writing values
+ yield dut.flg.eq(0)
+ yield dut.alu_flgs.eq(Repl(1, dut.alu_flgs.width))
+ yield dut.wr_en.eq(1)
+ yield dut.flg.user_mode.eq(0)
+ yield dut.rd_addr.eq(dut.zx.idx) # can be anything except flg register
+ yield dut.rd.eq(0xFFFF0000) # this does not matter
+ yield from step()
+ assert (yield dut.flg) == (0x0000001f ), f'ERROR: alu is not writing to flg register'
+
+
+ sim = Simulator(dut)
+ sim.add_clock(1e-6)
+ sim.add_sync_process(proc1)
+
+ with sim.write_vcd(filename):
+ sim.run()
+
+
# class ASAP32Core(Elaboratable):
# def __init__(self):
@@ -292,7 +429,7 @@ class ALU(Elaboratable):
m.d.comb += self.c_out.eq(self.tmp[32])
m.d.comb += self.overflow.eq(self.tmp[32] ^ self.tmp[31])
m.d.comb += self.out.eq(self.tmp[0:32])
- m.d.comb += self.neg.eq(self.out.as_signed() < 0)
+ m.d.comb += self.neg.eq(self.out[31])
m.d.comb += self.zero.eq(self.out == 0)
m.d.comb += self.odd.eq(self.out[0])
@@ -427,7 +564,7 @@ def test_alu(filename="alu.vcd"):
if __name__ == '__main__':
reg = Reg()
- cmd(reg, None)
+ cmd(reg, test_reg)
# hdl = ALU()
# cmd(hdl, test_alu)