flow/isd: add freeze register

diff --git a/migen/flow/isd.py b/migen/flow/isd.py
index 36c893fc271eba0bdefdd98d195ecddb5be4d3d5..02339d498bec261ab000724e54c33f3e78137b13 100644 (file)
--- a/migen/flow/isd.py
+++ b/migen/flow/isd.py
@@ -4,14 +4,15 @@ from migen.flow.hooks import DFGHook
 
 ISD_MAGIC = 0x6ab4
 
-# TODO: add freeze
 class EndpointReporter:
        def __init__(self, endpoint, nbits):
                self.endpoint = endpoint
+               self.nbits = nbits
                self.reset = Signal()
+               self.freeze = Signal()
                
-               self._ack_count = RegisterField("ack_count", nbits, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
-               self._nack_count = RegisterField("nack_count", nbits, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
+               self._ack_count = RegisterField("ack_count", self.nbits, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
+               self._nack_count = RegisterField("nack_count", self.nbits, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
                self._cur_stb = Field("cur_stb", 1, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
                self._cur_ack = Field("cur_ack", 1, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
                self._cur_status = RegisterFields("cur_status", [self._cur_stb, self._cur_ack])
@@ -22,8 +23,8 @@ class EndpointReporter:
        def get_fragment(self):
                stb = Signal()
                ack = Signal()
-               ack_count = self._ack_count.field.w
-               nack_count = self._nack_count.field.w
+               ack_count = Signal(BV(self.nbits))
+               nack_count = Signal(BV(self.nbits))
                comb = [
                        self._cur_stb.w.eq(stb),
                        self._cur_ack.w.eq(ack)
@@ -44,6 +45,10 @@ class EndpointReporter:
                                                nack_count.eq(nack_count + 1)
                                        )
                                )
+                       ),
+                       If(~self.freeze,
+                               self._ack_count.field.w.eq(ack_count),
+                               self._nack_count.field.w.eq(nack_count)
                        )
                ]
                return Fragment(comb, sync)
@@ -55,6 +60,7 @@ class DFGReporter(DFGHook):
                self._r_magic = RegisterField("magic", 16, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
                self._r_neps = RegisterField("neps", 8, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
                self._r_nbits = RegisterField("nbits", 8, access_bus=READ_ONLY, access_dev=WRITE_ONLY)
+               self._r_freeze = RegisterField("freeze", 1)
                self._r_reset = RegisterRaw("reset", 1)
                
                self.order = []
@@ -69,7 +75,8 @@ class DFGReporter(DFGHook):
                        print("#" + str(n) + ": " + str(u) + ":" + ep + "  ->  " + str(v))
        
        def get_registers(self):
-               registers = [self._r_magic, self._r_neps, self._r_nbits, self._r_reset]
+               registers = [self._r_magic, self._r_neps, self._r_nbits,
+                       self._r_freeze, self._r_reset]
                for u, ep, v in self.order:
                        registers += self.nodepair_to_ep[(u, v)][ep].get_registers()
                return registers
@@ -80,5 +87,9 @@ class DFGReporter(DFGHook):
                        self._r_neps.field.w.eq(len(self.order)),
                        self._r_nbits.field.w.eq(self._nbits)
                ]
-               comb += [h.reset.eq(self._r_reset.re) for h in self.hooks_iter()]
+               for h in self.hooks_iter():
+                       comb += [
+                               h.freeze.eq(self._r_freeze.field.r),
+                               h.reset.eq(self._r_reset.re)
+                       ]
                return Fragment(comb) + super().get_fragment()