Add packed struct overlay for external register bitfields. #84

src/peakrdl_regblock/hwif/generators.py

@@ -20,8 +20,8 @@ def __init__(self, hwif: 'Hwif', hwif_name: str) -> None:
 
         self.hwif_report_stack = [hwif_name]
 
-    def push_struct(self, type_name: str, inst_name: str, array_dimensions: Optional[List[int]] = None) -> None: # type: ignore
-        super().push_struct(type_name, inst_name, array_dimensions)
+    def push_struct(self, type_name: str, inst_name: str, array_dimensions: Optional[List[int]] = None, packed: bool = False) -> None: # type: ignore
+        super().push_struct(type_name, inst_name, array_dimensions, packed)
 
         if array_dimensions:
             array_suffix = "".join([f"[0:{dim-1}]" for dim in array_dimensions])
@@ -52,14 +52,14 @@ class InputStructGenerator_Hier(HWIFStructGenerator):
     def __init__(self, hwif: 'Hwif') -> None:
         super().__init__(hwif, "hwif_in")
 
-    def get_typdef_name(self, node:'Node') -> str:
+    def get_typdef_name(self, node:'Node', suffix: str = "") -> str:
         base = node.get_rel_path(
             self.top_node.parent,
             hier_separator="__",
             array_suffix="x",
             empty_array_suffix="x"
         )
-        return f'{base}__in_t'
+        return f'{base}{suffix}__in_t'
 
     def enter_Signal(self, node: 'SignalNode') -> None:
         # only emit the signal if design scanner detected it is actually being used
@@ -95,15 +95,48 @@ def enter_Reg(self, node: 'RegNode') -> Optional[WalkerAction]:
         super().enter_Reg(node)
         if node.external:
             width = min(self.hwif.ds.cpuif_data_width, node.get_property('regwidth'))
+            n_subwords = node.get_property("regwidth") // node.get_property("accesswidth")
             if node.has_sw_readable:
                 self.add_member("rd_ack")
-                self.add_member("rd_data", width)
+                self.add_external_reg_rd_data(node, width, n_subwords)
             if node.has_sw_writable:
                 self.add_member("wr_ack")
             return WalkerAction.SkipDescendants
 
         return WalkerAction.Continue
 
+    def add_external_reg_rd_data(self, node: 'RegNode', width: int, n_subwords: int) -> None:
+        if n_subwords == 1:
+            # External reg is 1 sub-word. Add a packed struct to represent it
+            type_name = self.get_typdef_name(node, "__fields")
+            self.push_struct(type_name, "rd_data", packed=True)
+            current_bit = 0
+            for field in node.fields():
+                if not field.is_sw_readable:
+                    continue
+                if field.low > current_bit:
+                    # Add padding
+                    self.add_member(
+                        f"_reserved_{field.low - 1}_{current_bit}",
+                        field.low - current_bit
+                    )
+                self.add_member(
+                    kwf(field.inst_name),
+                    field.width
+                )
+                current_bit = field.high + 1
+
+            # Add end padding if needed
+            if current_bit != width:
+                self.add_member(
+                    f"_reserved_{width - 1}_{current_bit}",
+                    width - current_bit
+                )
+            self.pop_struct()
+        else:
+            # Multiple sub-words. Cannot generate a struct
+            self.add_member("rd_data", width)
+
     def enter_Field(self, node: 'FieldNode') -> None:
         type_name = self.get_typdef_name(node)
         self.push_struct(type_name, kwf(node.inst_name))
@@ -150,14 +183,14 @@ class OutputStructGenerator_Hier(HWIFStructGenerator):
     def __init__(self, hwif: 'Hwif') -> None:
         super().__init__(hwif, "hwif_out")
 
-    def get_typdef_name(self, node:'Node') -> str:
+    def get_typdef_name(self, node:'Node', suffix: str = "") -> str:
         base = node.get_rel_path(
             self.top_node.parent,
             hier_separator="__",
             array_suffix="x",
             empty_array_suffix="x"
         )
-        return f'{base}__out_t'
+        return f'{base}{suffix}__out_t'
 
     def _add_external_block_members(self, node: 'AddressableNode') -> None:
         self.add_member("req")
@@ -193,12 +226,44 @@ def enter_Reg(self, node: 'RegNode') -> Optional[WalkerAction]:
             self.add_member("req", n_subwords)
             self.add_member("req_is_wr")
             if node.has_sw_writable:
-                self.add_member("wr_data", width)
-                self.add_member("wr_biten", width)
+                self.add_external_reg_wr_data("wr_data", node, width, n_subwords)
+                self.add_external_reg_wr_data("wr_biten", node, width, n_subwords)
             return WalkerAction.SkipDescendants
 
         return WalkerAction.Continue
 
+    def add_external_reg_wr_data(self, name: str, node: 'RegNode', width: int, n_subwords: int) -> None:
+        if n_subwords == 1:
+            # External reg is 1 sub-word. Add a packed struct to represent it
+            type_name = self.get_typdef_name(node, "__fields")
+            self.push_struct(type_name, name, packed=True)
+            current_bit = 0
+            for field in node.fields():
+                if not field.is_sw_writable:
+                    continue
+                if field.low > current_bit:
+                    # Add padding
+                    self.add_member(
+                        f"_reserved_{field.low - 1}_{current_bit}",
+                        field.low - current_bit
+                    )
+                self.add_member(
+                    kwf(field.inst_name),
+                    field.width
+                )
+                current_bit = field.high + 1
+
+            # Add end padding if needed
+            if current_bit != width:
+                self.add_member(
+                    f"_reserved_{width - 1}_{current_bit}",
+                    width - current_bit
+                )
+            self.pop_struct()
+        else:
+            # Multiple sub-words. Cannot generate a struct
+            self.add_member(name, width)
+
     def enter_Field(self, node: 'FieldNode') -> None:
         type_name = self.get_typdef_name(node)
         self.push_struct(type_name, kwf(node.inst_name))
@@ -229,7 +294,7 @@ def exit_Reg(self, node: 'RegNode') -> None:
 
 #-------------------------------------------------------------------------------
 class InputStructGenerator_TypeScope(InputStructGenerator_Hier):
-    def get_typdef_name(self, node:'Node') -> str:
+    def get_typdef_name(self, node:'Node', suffix: str = "") -> str:
         scope_path = node.get_global_type_name("__")
         if scope_path is None:
             # Unable to determine a reusable type name. Fall back to hierarchical path
@@ -242,10 +307,10 @@ def get_typdef_name(self, node:'Node') -> str:
         else:
             extra_suffix = ""
 
-        return f'{scope_path}{extra_suffix}__in_t'
+        return f'{scope_path}{extra_suffix}{suffix}__in_t'
 
 class OutputStructGenerator_TypeScope(OutputStructGenerator_Hier):
-    def get_typdef_name(self, node:'Node') -> str:
+    def get_typdef_name(self, node:'Node', suffix: str = "") -> str:
         scope_path = node.get_global_type_name("__")
         if scope_path is None:
             # Unable to determine a reusable type name. Fall back to hierarchical path
@@ -258,7 +323,7 @@ def get_typdef_name(self, node:'Node') -> str:
         else:
             extra_suffix = ""
 
-        return f'{scope_path}{extra_suffix}__out_t'
+        return f'{scope_path}{extra_suffix}{suffix}__out_t'
 
 #-------------------------------------------------------------------------------
 class EnumGenerator:

src/peakrdl_regblock/struct_generator.py

@@ -41,18 +41,26 @@ def __str__(self) -> str:
 
 
 class _TypedefStruct(_StructBase):
-    def __init__(self, type_name: str, inst_name: Optional[str] = None, array_dimensions: Optional[List[int]] = None):
+    def __init__(self, type_name: str, inst_name: Optional[str] = None, array_dimensions: Optional[List[int]] = None, packed: bool = False):
         super().__init__()
         self.type_name = type_name
         self.inst_name = inst_name
         self.array_dimensions = array_dimensions
+        self.packed = packed
 
     def __str__(self) -> str:
-        return (
-            "typedef struct {\n"
-            + super().__str__()
-            + f"\n}} {self.type_name};"
-        )
+        if self.packed:
+            return (
+                "typedef struct packed {\n"
+                + super().__str__()
+                + f"\n}} {self.type_name};"
+            )
+        else:
+            return (
+                "typedef struct {\n"
+                + super().__str__()
+                + f"\n}} {self.type_name};"
+            )
 
     @property
     def instantiation(self) -> str:
@@ -167,8 +175,8 @@ def __init__(self) -> None:
         super().__init__()
         self.typedefs = OrderedDict() # type: OrderedDict[str, _TypedefStruct]
 
-    def push_struct(self, type_name: str, inst_name: str, array_dimensions: Optional[List[int]] = None) -> None: # type: ignore # pylint: disable=arguments-renamed
-        s = _TypedefStruct(type_name, inst_name, array_dimensions)
+    def push_struct(self, type_name: str, inst_name: str, array_dimensions: Optional[List[int]] = None, packed = False) -> None: # type: ignore # pylint: disable=arguments-renamed
+        s = _TypedefStruct(type_name, inst_name, array_dimensions, packed)
         self._struct_stack.append(s)
 
     def pop_struct(self) -> None:

tests/test_external/regblock.rdl

@@ -2,13 +2,18 @@ addrmap top {
     reg my_reg {
         field {sw=rw; hw=r;} whatever[32] = 0;
     };
+    reg my_reg_alt {
+        field {sw=r; hw=w;} whatever_a[3:2] = 0;
+        field {sw=w; hw=r;} whatever_b[4:4] = 0;
+        field {sw=rw; hw=r;} whatever_c[15:8] = 0;
+    };
     reg my_wide_reg {
         regwidth = 64;
         accesswidth = 32;
         field {sw=rw; hw=r;} whatever = 0;
     };
 
-    external my_reg ext_reg @ 0x00;
+    external my_reg_alt ext_reg @ 0x00;
     my_reg int_reg @ 0x04;
     external my_wide_reg wide_ext_reg @ 0x10;
     external my_reg ext_reg_array[32] @ 0x100 += 4;