Implement new SVInt object to defer literal expansion and allow bit-fiddling operations. Fix invalid bit-slicing of literals if field reset value is a constant. #71

src/peakrdl_regblock/addr_decode.py

@@ -3,10 +3,11 @@ from typing import TYPE_CHECKING, Union, List, Optional
 from systemrdl.node import FieldNode, RegNode
 from systemrdl.walker import WalkerAction
 
-from .utils import get_indexed_path, get_sv_int
+from .utils import get_indexed_path
 from .struct_generator import RDLStructGenerator
 from .forloop_generator import RDLForLoopGenerator
 from .identifier_filter import kw_filter as kwf
+from .sv_int import SVInt
 
 if TYPE_CHECKING:
     from .exporter import RegblockExporter
@@ -149,7 +150,7 @@ class DecodeLogicGenerator(RDLForLoopGenerator):
             # Is an external block
             addr_str = self._get_address_str(node)
             strb = self.addr_decode.get_external_block_access_strobe(node)
-            rhs = f"cpuif_req_masked & (cpuif_addr >= {addr_str}) & (cpuif_addr <= {addr_str} + {get_sv_int(node.size - 1, self.addr_decode.exp.ds.addr_width)})"
+            rhs = f"cpuif_req_masked & (cpuif_addr >= {addr_str}) & (cpuif_addr <= {addr_str} + {SVInt(node.size - 1, self.addr_decode.exp.ds.addr_width)})"
             self.add_content(f"{strb} = {rhs};")
             self.add_content(f"is_external |= {rhs};")
             return WalkerAction.SkipDescendants
@@ -158,12 +159,12 @@ class DecodeLogicGenerator(RDLForLoopGenerator):
 
 
     def _get_address_str(self, node: 'AddressableNode', subword_offset: int=0) -> str:
-        a = get_sv_int(
+        a = str(SVInt(
             node.raw_absolute_address - self.addr_decode.top_node.raw_absolute_address + subword_offset,
             self.addr_decode.exp.ds.addr_width
-        )
+        ))
         for i, stride in enumerate(self._array_stride_stack):
-            a += f" + i{i}*{get_sv_int(stride, self.addr_decode.exp.ds.addr_width)}"
+            a += f" + i{i}*{SVInt(stride, self.addr_decode.exp.ds.addr_width)}"
         return a
 
 

src/peakrdl_regblock/dereferencer.py

@@ -2,7 +2,7 @@ from typing import TYPE_CHECKING, Union, Optional
 from systemrdl.node import AddrmapNode, FieldNode, SignalNode, RegNode, AddressableNode
 from systemrdl.rdltypes import PropertyReference
 
-from .utils import get_sv_int
+from .sv_int import SVInt
 
 if TYPE_CHECKING:
     from .exporter import RegblockExporter, DesignState
@@ -38,7 +38,7 @@ class Dereferencer:
     def top_node(self) -> AddrmapNode:
         return self.exp.ds.top_node
 
-    def get_value(self, obj: Union[int, FieldNode, SignalNode, PropertyReference], width: Optional[int] = None) -> str:
+    def get_value(self, obj: Union[int, FieldNode, SignalNode, PropertyReference], width: Optional[int] = None) -> Union[SVInt, str]:
         """
         Returns the Verilog string that represents the readable value associated
         with the object.
@@ -52,20 +52,20 @@ class Dereferencer:
         """
         if isinstance(obj, int):
             # Is a simple scalar value
-            return get_sv_int(obj, width)
+            return SVInt(obj, width)
 
         if isinstance(obj, FieldNode):
             if obj.implements_storage:
                 return self.field_logic.get_storage_identifier(obj)
 
             if self.hwif.has_value_input(obj):
-                return self.hwif.get_input_identifier(obj)
+                return self.hwif.get_input_identifier(obj, width)
 
             # Field does not have a storage element, nor does it have a HW input
             # must be a constant value as defined by its reset value
             reset_value = obj.get_property('reset')
             if reset_value is not None:
-                return self.get_value(reset_value)
+                return self.get_value(reset_value, obj.width)
             else:
                 # No reset value defined!
                 obj.env.msg.warning(
@@ -76,11 +76,11 @@ class Dereferencer:
 
         if isinstance(obj, SignalNode):
             # Signals are always inputs from the hwif
-            return self.hwif.get_input_identifier(obj)
+            return self.hwif.get_input_identifier(obj, width)
 
         if isinstance(obj, PropertyReference):
             if isinstance(obj.node, FieldNode):
-                return self.get_field_propref_value(obj.node, obj.name)
+                return self.get_field_propref_value(obj.node, obj.name, width)
             elif isinstance(obj.node, RegNode):
                 return self.get_reg_propref_value(obj.node, obj.name)
             else:
@@ -89,7 +89,12 @@ class Dereferencer:
         raise RuntimeError(f"Unhandled reference to: {obj}")
 
 
-    def get_field_propref_value(self, field: FieldNode, prop_name: str) -> str:
+    def get_field_propref_value(
+        self,
+        field: FieldNode,
+        prop_name: str,
+        width: Optional[int] = None,
+    ) -> Union[SVInt, str]:
         # Value reduction properties.
         # Wrap with the appropriate Verilog reduction operator
         if prop_name == "anded":
@@ -115,7 +120,7 @@ class Dereferencer:
             'reset',
             'resetsignal',
         }:
-            return self.get_value(field.get_property(prop_name))
+            return self.get_value(field.get_property(prop_name), width)
 
         # Field Next
         if prop_name == "next":
@@ -124,7 +129,7 @@ class Dereferencer:
                 # unset by the user, points to the implied internal signal
                 return self.field_logic.get_field_combo_identifier(field, "next")
             else:
-                return self.get_value(prop_value)
+                return self.get_value(prop_value, width)
 
         # References to another component value, or an implied input
         if prop_name in {'hwclr', 'hwset'}:
@@ -163,7 +168,7 @@ class Dereferencer:
                 else:
                     return f"!({self.get_value(prop_value)})"
             else:
-                return self.get_value(prop_value)
+                return self.get_value(prop_value, width)
 
         if prop_name == "swacc":
             return self.field_logic.get_swacc_identifier(field)
@@ -232,7 +237,7 @@ class Dereferencer:
         if isinstance(obj, SignalNode):
             s = self.get_value(obj)
             if obj.get_property('activehigh'):
-                return s
+                return str(s)
             else:
                 return f"~{s}"
 

src/peakrdl_regblock/field_logic/__init__.py

@@ -1,4 +1,4 @@
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Union
 
 from systemrdl.rdltypes import PrecedenceType, InterruptType
 
@@ -11,6 +11,7 @@ from . import hw_set_clr
 from . import hw_interrupts
 
 from ..utils import get_indexed_path
+from ..sv_int import SVInt
 
 from .generators import CombinationalStructGenerator, FieldStorageStructGenerator, FieldLogicGenerator
 
@@ -99,12 +100,12 @@ class FieldLogic:
         """
         prop_value = field.get_property('incr')
         if prop_value:
-            return self.exp.dereferencer.get_value(prop_value)
+            return str(self.exp.dereferencer.get_value(prop_value))
 
         # unset by the user, points to the implied input signal
         return self.exp.hwif.get_implied_prop_input_identifier(field, "incr")
 
-    def get_counter_incrvalue(self, field: 'FieldNode') -> str:
+    def get_counter_incrvalue(self, field: 'FieldNode') -> Union[SVInt, str]:
         """
         Return the string that represents the field's increment value
         """
@@ -115,7 +116,7 @@ class FieldLogic:
             return self.exp.hwif.get_implied_prop_input_identifier(field, "incrvalue")
         return "1'b1"
 
-    def get_counter_incrsaturate_value(self, field: 'FieldNode') -> str:
+    def get_counter_incrsaturate_value(self, field: 'FieldNode') -> Union[SVInt, str]:
         prop_value = field.get_property('incrsaturate')
         if prop_value is True:
             return self.exp.dereferencer.get_value(2**field.width - 1, field.width)
@@ -127,7 +128,7 @@ class FieldLogic:
         """
         return field.get_property('incrsaturate') is not False
 
-    def get_counter_incrthreshold_value(self, field: 'FieldNode') -> str:
+    def get_counter_incrthreshold_value(self, field: 'FieldNode') -> Union[SVInt, str]:
         prop_value = field.get_property('incrthreshold')
         if isinstance(prop_value, bool):
             # No explicit value set. use max
@@ -140,12 +141,12 @@ class FieldLogic:
         """
         prop_value = field.get_property('decr')
         if prop_value:
-            return self.exp.dereferencer.get_value(prop_value)
+            return str(self.exp.dereferencer.get_value(prop_value))
 
         # unset by the user, points to the implied input signal
         return self.exp.hwif.get_implied_prop_input_identifier(field, "decr")
 
-    def get_counter_decrvalue(self, field: 'FieldNode') -> str:
+    def get_counter_decrvalue(self, field: 'FieldNode') -> Union[SVInt, str]:
         """
         Return the string that represents the field's decrement value
         """
@@ -156,7 +157,7 @@ class FieldLogic:
             return self.exp.hwif.get_implied_prop_input_identifier(field, "decrvalue")
         return "1'b1"
 
-    def get_counter_decrsaturate_value(self, field: 'FieldNode') -> str:
+    def get_counter_decrsaturate_value(self, field: 'FieldNode') -> Union[SVInt, str]:
         prop_value = field.get_property('decrsaturate')
         if prop_value is True:
             return f"{field.width}'d0"
@@ -168,7 +169,7 @@ class FieldLogic:
         """
         return field.get_property('decrsaturate') is not False
 
-    def get_counter_decrthreshold_value(self, field: 'FieldNode') -> str:
+    def get_counter_decrthreshold_value(self, field: 'FieldNode') -> Union[SVInt, str]:
         prop_value = field.get_property('decrthreshold')
         if isinstance(prop_value, bool):
             # No explicit value set. use min

src/peakrdl_regblock/field_logic/hw_set_clr.py

@@ -17,7 +17,7 @@ class HWSet(NextStateConditional):
             identifier = self.exp.hwif.get_implied_prop_input_identifier(field, "hwset")
         else:
             # signal or field
-            identifier = self.exp.dereferencer.get_value(prop)
+            identifier = str(self.exp.dereferencer.get_value(prop))
         return identifier
 
     def get_assignments(self, field: 'FieldNode') -> List[str]:
@@ -50,7 +50,7 @@ class HWClear(NextStateConditional):
             identifier = self.exp.hwif.get_implied_prop_input_identifier(field, "hwclr")
         else:
             # signal or field
-            identifier = self.exp.dereferencer.get_value(prop)
+            identifier = str(self.exp.dereferencer.get_value(prop))
         return identifier
 
     def get_assignments(self, field: 'FieldNode') -> List[str]:

src/peakrdl_regblock/field_logic/hw_write.py

@@ -24,7 +24,7 @@ class AlwaysWrite(NextStateConditional):
     def get_assignments(self, field: 'FieldNode') -> List[str]:
         hwmask = field.get_property('hwmask')
         hwenable = field.get_property('hwenable')
-        I = self.exp.hwif.get_input_identifier(field)
+        I = str(self.exp.hwif.get_input_identifier(field))
         R = self.exp.field_logic.get_storage_identifier(field)
         if hwmask is not None:
             M = self.exp.dereferencer.get_value(hwmask)
@@ -55,7 +55,7 @@ class WEWrite(AlwaysWrite):
             identifier = self.exp.hwif.get_implied_prop_input_identifier(field, "we")
         else:
             # signal or field
-            identifier = self.exp.dereferencer.get_value(prop)
+            identifier = str(self.exp.dereferencer.get_value(prop))
         return identifier
 
 class WELWrite(AlwaysWrite):
@@ -73,5 +73,5 @@ class WELWrite(AlwaysWrite):
             identifier = self.exp.hwif.get_implied_prop_input_identifier(field, "wel")
         else:
             # signal or field
-            identifier = self.exp.dereferencer.get_value(prop)
+            identifier = str(self.exp.dereferencer.get_value(prop))
         return f"!{identifier}"

src/peakrdl_regblock/hwif/__init__.py

@@ -1,10 +1,11 @@
-from typing import TYPE_CHECKING, Union, Set, Dict, Optional, TextIO, Type, List
+from typing import TYPE_CHECKING, Union, Optional, TextIO
 
 from systemrdl.node import AddrmapNode, SignalNode, FieldNode, RegNode, AddressableNode
-from systemrdl.rdltypes import PropertyReference, UserEnum
+from systemrdl.rdltypes import PropertyReference
 
 from ..utils import get_indexed_path
 from ..identifier_filter import kw_filter as kwf
+from ..sv_int import SVInt
 
 from .generators import InputStructGenerator_Hier, OutputStructGenerator_Hier
 from .generators import InputStructGenerator_TypeScope, OutputStructGenerator_TypeScope
@@ -127,7 +128,11 @@ class Hwif:
         return obj.is_hw_readable
 
 
-    def get_input_identifier(self, obj: Union[FieldNode, SignalNode, PropertyReference]) -> str:
+    def get_input_identifier(
+        self,
+        obj: Union[FieldNode, SignalNode, PropertyReference],
+        width: Optional[int] = None,
+    ) -> Union[SVInt, str]:
         """
         Returns the identifier string that best represents the input object.
 
@@ -143,7 +148,7 @@ class Hwif:
             next_value = obj.get_property('next')
             if next_value is not None:
                 # 'next' property replaces the inferred input signal
-                return self.exp.dereferencer.get_value(next_value)
+                return self.exp.dereferencer.get_value(next_value, width)
             # Otherwise, use inferred
             path = get_indexed_path(self.top_node, obj)
             return "hwif_in." + path + ".next"

src/peakrdl_regblock/hwif/generators.py

@@ -5,7 +5,7 @@ from systemrdl.walker import WalkerAction
 
 from ..struct_generator import RDLFlatStructGenerator
 from ..identifier_filter import kw_filter as kwf
-from ..utils import get_sv_int
+from ..sv_int import SVInt
 
 if TYPE_CHECKING:
     from systemrdl.node import Node, SignalNode, AddressableNode, RegfileNode
@@ -289,7 +289,7 @@ class EnumGenerator:
 
         lines = []
         for enum_member in user_enum:
-            lines.append(f"    {prefix}__{enum_member.name} = {get_sv_int(enum_member.value)}")
+            lines.append(f"    {prefix}__{enum_member.name} = {SVInt(enum_member.value)}")
 
         return (
             "typedef enum {\n"

src/peakrdl_regblock/read_buffering/__init__.py

@@ -1,10 +1,11 @@
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Union
 
-from systemrdl.node import AddrmapNode, RegNode, FieldNode, SignalNode
+from systemrdl.node import AddrmapNode, RegNode, SignalNode
 
 from .storage_generator import RBufStorageStructGenerator
 from .implementation_generator import RBufLogicGenerator
 from ..utils import get_indexed_path
+from ..sv_int import SVInt
 
 if TYPE_CHECKING:
     from ..exporter import RegblockExporter
@@ -47,12 +48,12 @@ class ReadBuffering:
         elif isinstance(trigger, SignalNode):
             s = self.exp.dereferencer.get_value(trigger)
             if trigger.get_property('activehigh'):
-                return s
+                return str(s)
             else:
                 return f"~{s}"
         else:
             # Trigger is a field or propref bit
-            return self.exp.dereferencer.get_value(trigger)
+            return str(self.exp.dereferencer.get_value(trigger))
 
     def get_rbuf_data(self, node: RegNode) -> str:
         return "rbuf_storage." + get_indexed_path(self.top_node, node) + ".data"

src/peakrdl_regblock/readback/generators.py

@@ -5,6 +5,8 @@ from systemrdl.walker import WalkerAction
 
 from ..forloop_generator import RDLForLoopGenerator, LoopBody
 
+from ..utils import do_bitswap, do_slice
+
 if TYPE_CHECKING:
     from ..exporter import RegblockExporter
 
@@ -147,7 +149,7 @@ class ReadbackAssignmentGenerator(RDLForLoopGenerator):
             value = self.exp.dereferencer.get_value(field)
             if field.msb < field.lsb:
                 # Field gets bitswapped since it is in [low:high] orientation
-                value = f"{{<<{{{value}}}}}"
+                value = do_bitswap(value)
 
             self.add_content(f"assign readback_array[{self.current_offset_str}][{field.high}:{field.low}] = {rd_strb} ? {value} : '0;")
 
@@ -223,9 +225,9 @@ class ReadbackAssignmentGenerator(RDLForLoopGenerator):
                     f_low = field.width - 1 - f_low
                     f_high = field.width - 1 - f_high
                     f_low, f_high = f_high, f_low
-                    value = f"{{<<{{{self.exp.dereferencer.get_value(field)}[{f_high}:{f_low}]}}}}"
+                    value = do_bitswap(do_slice(self.exp.dereferencer.get_value(field), f_high, f_low))
                 else:
-                    value = self.exp.dereferencer.get_value(field) + f"[{f_high}:{f_low}]"
+                    value = do_slice(self.exp.dereferencer.get_value(field), f_high, f_low)
 
                 self.add_content(f"assign readback_array[{self.current_offset_str}][{r_high}:{r_low}] = {rd_strb} ? {value} : '0;")
                 bidx = accesswidth
@@ -234,7 +236,7 @@ class ReadbackAssignmentGenerator(RDLForLoopGenerator):
                 value = self.exp.dereferencer.get_value(field)
                 if field.msb < field.lsb:
                     # Field gets bitswapped since it is in [low:high] orientation
-                    value = f"{{<<{{{value}}}}}"
+                    value = do_bitswap(value)
                 self.add_content(f"assign readback_array[{self.current_offset_str}][{field.high}:{field.low}] = {rd_strb} ? {value} : '0;")
                 bidx = field.high + 1
 
@@ -299,7 +301,7 @@ class ReadbackAssignmentGenerator(RDLForLoopGenerator):
                     value = self.exp.dereferencer.get_value(field)
                     if field.msb < field.lsb:
                         # Field gets bitswapped since it is in [low:high] orientation
-                        value = f"{{<<{{{value}}}}}"
+                        value = do_bitswap(value)
 
                     self.add_content(f"assign readback_array[{self.current_offset_str}][{high}:{low}] = {rd_strb} ? {value} : '0;")
 
@@ -328,9 +330,9 @@ class ReadbackAssignmentGenerator(RDLForLoopGenerator):
                         f_high = field.width - 1 - f_high
                         f_low, f_high = f_high, f_low
 
-                        value = f"{{<<{{{self.exp.dereferencer.get_value(field)}[{f_high}:{f_low}]}}}}"
+                        value = do_bitswap(do_slice(self.exp.dereferencer.get_value(field), f_high, f_low))
                     else:
-                        value = self.exp.dereferencer.get_value(field) + f"[{f_high}:{f_low}]"
+                        value = do_slice(self.exp.dereferencer.get_value(field), f_high, f_low)
 
                     self.add_content(f"assign readback_array[{self.current_offset_str}][{r_high}:{r_low}] = {rd_strb} ? {value} : '0;")
 
@@ -358,9 +360,9 @@ class ReadbackAssignmentGenerator(RDLForLoopGenerator):
                         f_high = field.width - 1 - f_high
                         f_low, f_high = f_high, f_low
 
-                        value = f"{{<<{{{self.exp.dereferencer.get_value(field)}[{f_high}:{f_low}]}}}}"
+                        value = do_bitswap(do_slice(self.exp.dereferencer.get_value(field), f_high, f_low))
                     else:
-                        value = self.exp.dereferencer.get_value(field) + f"[{f_high}:{f_low}]"
+                        value = do_slice(self.exp.dereferencer.get_value(field), f_high, f_low)
 
                     self.add_content(f"assign readback_array[{self.current_offset_str}][{r_high}:{r_low}] = {rd_strb} ? {value} : '0;")
 

src/peakrdl_regblock/sv_int.py

@@ -0,0 +1,17 @@
+from typing import Optional
+
+class SVInt:
+    def __init__(self, value: int, width: Optional[int] = None) -> None:
+        self.value = value
+        self.width = width
+
+    def __str__(self) -> str:
+        if self.width is not None:
+            # Explicit width
+            return f"{self.width}'h{self.value:x}"
+        elif self.value.bit_length() > 32:
+            # SV standard only enforces that unsized literals shall be at least 32-bits
+            # To support larger literals, they need to be sized explicitly
+            return f"{self.value.bit_length()}'h{self.value:x}"
+        else:
+            return f"'h{self.value:x}"

src/peakrdl_regblock/utils.py

@@ -1,10 +1,11 @@
 import re
-from typing import Match, Union, Optional
+from typing import Match, Union
 
 from systemrdl.rdltypes.references import PropertyReference
 from systemrdl.node import Node, AddrmapNode
 
 from .identifier_filter import kw_filter as kwf
+from .sv_int import SVInt
 
 def get_indexed_path(top_node: Node, target_node: Node) -> str:
     """
@@ -65,13 +66,36 @@ def ref_is_internal(top_node: AddrmapNode, ref: Union[Node, PropertyReference])
     # This is considerd internal for this exporter
     return True
 
-def get_sv_int(n: int, width: Optional[int]=None) -> str:
+
-    if width is not None:
+def do_slice(value: Union[SVInt, str], high: int, low: int) -> Union[SVInt, str]:
-        # Explicit width
+    if isinstance(value, str):
-        return f"{width}'h{n:x}"
+        # If string, assume this is an identifier. Append bit-slice
-    elif n.bit_length() > 32:
+        if high == low:
-        # SV standard only enforces that unsized literals shall be at least 32-bits
+            return f"{value}[{low}]"
-        # To support larger literals, they need to be sized explicitly
-        return f"{n.bit_length()}'h{n:x}"
         else:
-        return f"'h{n:x}"
+            return f"{value}[{high}:{low}]"
+    else:
+        # it is an SVInt literal. Slice it down
+        mask = (1 << (high + 1)) - 1
+        v = (value.value & mask) >> low
+
+        if value.width is not None:
+            w = high - low + 1
+        else:
+            w = None
+
+        return SVInt(v, w)
+
+def do_bitswap(value: Union[SVInt, str]) -> Union[SVInt, str]:
+    if isinstance(value, str):
+        # If string, assume this is an identifier. Wrap in a streaming operator
+        return "{<<{" + value + "}}"
+    else:
+        # it is an SVInt literal. bitswap it
+        assert value.width is not None # width must be known!
+        v = value.value
+        vswap = 0
+        for _ in range(value.width):
+            vswap = (vswap << 1) + (v & 1)
+            v >>= 1
+        return SVInt(vswap, value.width)

src/peakrdl_regblock/write_buffering/__init__.py

@@ -5,6 +5,7 @@ from systemrdl.node import AddrmapNode, RegNode, FieldNode, SignalNode
 from .storage_generator import WBufStorageStructGenerator
 from .implementation_generator import WBufLogicGenerator
 from ..utils import get_indexed_path
+from ..sv_int import SVInt
 
 if TYPE_CHECKING:
     from ..exporter import RegblockExporter
@@ -42,7 +43,7 @@ class WriteBuffering:
         prefix = self.get_wbuf_prefix(node)
         return f"{prefix}.pending && {self.get_trigger(node)}"
 
-    def get_raw_trigger(self, node: 'RegNode') -> str:
+    def get_raw_trigger(self, node: 'RegNode') -> Union[SVInt, str]:
         trigger = node.get_property('wbuffer_trigger')
 
         if isinstance(trigger, RegNode):
@@ -67,7 +68,7 @@ class WriteBuffering:
             # Trigger is a field or propref bit
             return self.exp.dereferencer.get_value(trigger)
 
-    def get_trigger(self, node: Union[RegNode, FieldNode]) -> str:
+    def get_trigger(self, node: Union[RegNode, FieldNode]) -> Union[SVInt, str]:
         if isinstance(node, FieldNode):
             node = node.parent
         trigger = node.get_property('wbuffer_trigger')

tests/test_wide_regs/regblock.rdl

@@ -90,4 +90,22 @@ addrmap top {
     } counter_reg;
     counter_reg.f1_cnt->incr = r_reg2.f1->swacc;
     counter_reg.f2_cnt->incr = r_reg2.f2->swacc;
+
+    reg {
+        regwidth = 32;
+        accesswidth = 16;
+        default sw=r;
+        default hw=r;
+
+        field {} f1[31:0] = 0x1234_5678;
+    } r_reg3;
+
+    reg {
+        regwidth = 32;
+        accesswidth = 16;
+        default sw=r;
+        default hw=r;
+
+        field {} f1[0:31] = 0x1234_5678;
+    } r_reg4;
 };

tests/test_wide_regs/tb_template.sv

@@ -108,4 +108,14 @@
     // counter_reg
     cpuif.assert_read('h30, 16'h0204);
 
+    // r_reg3
+    cpuif.assert_read('h34, 16'h5678);
+    cpuif.assert_read('h36, 16'h1234);
+    assert(cb.hwif_out.r_reg3.f1.value == 32'h12345678);
+
+    // r_reg4
+    cpuif.assert_read('h38, 16'h2C48);
+    cpuif.assert_read('h3A, 16'h1E6A);
+    assert(cb.hwif_out.r_reg4.f1.value == 32'h12345678);
+
 {% endblock %}