Clean up ugly unconditional 'if(1)' conditionals in field logic. #50

src/peakrdl_regblock/field_logic/bases.py

@@ -64,7 +64,13 @@ class NextStateConditional:
         end
     """
 
+    # Assign to True if predicate can never evaluate to false.
+    # This will be generated as an 'else' clause, or a direct assignment
+    is_unconditional = False
+
+    # Optional comment to emit next to the conditional
     comment = ""
+
     def __init__(self, exp:'RegblockExporter'):
         self.exp = exp
 

src/peakrdl_regblock/field_logic/generators.py

@@ -212,10 +212,19 @@ class FieldLogicGenerator(RDLForLoopGenerator):
     def generate_field_storage(self, node: 'FieldNode') -> None:
         conditionals = self.field_logic.get_conditionals(node)
         extra_combo_signals = OrderedDict()
+        unconditional = None
+        new_conditionals = []
         for conditional in conditionals:
             for signal in conditional.get_extra_combo_signals(node):
                 extra_combo_signals[signal.name] = signal
 
+            if conditional.is_unconditional:
+                assert unconditional is None # Can only have one unconditional assignment per field
+                unconditional = conditional
+            else:
+                new_conditionals.append(conditional)
+        conditionals = new_conditionals
+
         resetsignal = node.get_property('resetsignal')
 
         reset_value = node.get_property('reset')
@@ -232,6 +241,7 @@ class FieldLogicGenerator(RDLForLoopGenerator):
             'field_logic': self.field_logic,
             'extra_combo_signals': extra_combo_signals,
             'conditionals': conditionals,
+            'unconditional': unconditional,
             'resetsignal': resetsignal,
             'get_always_ff_event': self.exp.dereferencer.get_always_ff_event,
             'get_value': self.exp.dereferencer.get_value,

src/peakrdl_regblock/field_logic/hw_interrupts.py

@@ -137,6 +137,7 @@ class PosedgeNonsticky(NextStateConditional):
     """
     Positive edge non-stickybit
     """
+    is_unconditional = True
     comment = "posedge nonsticky"
     def is_match(self, field: 'FieldNode') -> bool:
         return (
@@ -145,9 +146,6 @@ class PosedgeNonsticky(NextStateConditional):
             and field.get_property('intr type') == InterruptType.posedge
         )
 
-    def get_predicate(self, field: 'FieldNode') -> str:
-        return "1"
-
     def get_assignments(self, field: 'FieldNode') -> List[str]:
         I = self.exp.hwif.get_input_identifier(field)
         Iq = self.exp.field_logic.get_next_q_identifier(field)
@@ -160,6 +158,7 @@ class NegedgeNonsticky(NextStateConditional):
     """
     Negative edge non-stickybit
     """
+    is_unconditional = True
     comment = "negedge nonsticky"
     def is_match(self, field: 'FieldNode') -> bool:
         return (
@@ -168,9 +167,6 @@ class NegedgeNonsticky(NextStateConditional):
             and field.get_property('intr type') == InterruptType.negedge
         )
 
-    def get_predicate(self, field: 'FieldNode') -> str:
-        return "1"
-
     def get_assignments(self, field: 'FieldNode') -> List[str]:
         I = self.exp.hwif.get_input_identifier(field)
         Iq = self.exp.field_logic.get_next_q_identifier(field)
@@ -183,6 +179,7 @@ class BothedgeNonsticky(NextStateConditional):
     """
     edge-sensitive non-stickybit
     """
+    is_unconditional = True
     comment = "bothedge nonsticky"
     def is_match(self, field: 'FieldNode') -> bool:
         return (
@@ -191,9 +188,6 @@ class BothedgeNonsticky(NextStateConditional):
             and field.get_property('intr type') == InterruptType.bothedge
         )
 
-    def get_predicate(self, field: 'FieldNode') -> str:
-        return "1"
-
     def get_assignments(self, field: 'FieldNode') -> List[str]:
         I = self.exp.hwif.get_input_identifier(field)
         Iq = self.exp.field_logic.get_next_q_identifier(field)

src/peakrdl_regblock/field_logic/hw_write.py

@@ -10,7 +10,10 @@ class AlwaysWrite(NextStateConditional):
     """
     hw writable, without any qualifying we/wel
     """
+
+    is_unconditional = True
     comment = "HW Write"
+
     def is_match(self, field: 'FieldNode') -> bool:
         return (
             field.is_hw_writable
@@ -18,10 +21,6 @@ class AlwaysWrite(NextStateConditional):
             and not field.get_property('wel')
         )
 
-    def get_predicate(self, field: 'FieldNode') -> str:
-        # TODO: make exporter promote this to an "else"?
-        return "1"
-
     def get_assignments(self, field: 'FieldNode') -> List[str]:
         hwmask = field.get_property('hwmask')
         hwenable = field.get_property('hwenable')
@@ -42,6 +41,7 @@ class AlwaysWrite(NextStateConditional):
         ]
 
 class WEWrite(AlwaysWrite):
+    is_unconditional = False
     comment = "HW Write - we"
     def is_match(self, field: 'FieldNode') -> bool:
         return (
@@ -59,6 +59,7 @@ class WEWrite(AlwaysWrite):
         return identifier
 
 class WELWrite(AlwaysWrite):
+    is_unconditional = False
     comment = "HW Write - wel"
     def is_match(self, field: 'FieldNode') -> bool:
         return (

src/peakrdl_regblock/field_logic/sw_singlepulse.py

@@ -6,15 +6,11 @@ if TYPE_CHECKING:
     from systemrdl.node import FieldNode
 
 class Singlepulse(NextStateConditional):
+    is_unconditional = True
     comment = "singlepulse clears back to 0"
     def is_match(self, field: 'FieldNode') -> bool:
         return field.get_property('singlepulse')
 
-    def get_predicate(self, field: 'FieldNode') -> str:
-        # TODO: make exporter promote this to an "else"?
-        # Be mindful of sw/hw precedence. this would have to come last regardless
-        return "1"
-
     def get_assignments(self, field: 'FieldNode') -> List[str]:
         return [
             "next_c = '0;",

src/peakrdl_regblock/field_logic/templates/field_storage.sv

@@ -14,6 +14,19 @@ always_comb begin
         {%- endfor %}
     end
     {%- endfor %}
+    {%- if unconditional %}
+    {%- if conditionals %} else begin // {{unconditional.comment}}
+        {%- for assignment in unconditional.get_assignments(node) %}
+        {{assignment|indent}}
+        {%- endfor %}
+    end
+    {%- else %}
+    // {{unconditional.comment}}
+    {%- for assignment in unconditional.get_assignments(node) %}
+    {{assignment|indent}}
+    {%- endfor %}
+    {%- endif %}
+    {%- endif %}
 
     {%- if node.is_up_counter %}
     {{counter_macros.up_counter(node)}}