From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Wed, 24 Jun 2020 15:53:13 +0000 (+0100)
Subject: move comments to minerva LoadStoreInterface
X-Git-Tag: div_pipeline~288
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=908ffd9bb693701c3cbff9d5f714c28e4ac616b5;p=soc.git

move comments to minerva LoadStoreInterface
---

diff --git a/src/soc/minerva/units/loadstore.py b/src/soc/minerva/units/loadstore.py
index b14bbbd7..4fcc68b8 100644
--- a/src/soc/minerva/units/loadstore.py
+++ b/src/soc/minerva/units/loadstore.py
@@ -13,23 +13,26 @@ __all__ = ["LoadStoreUnitInterface", "BareLoadStoreUnit",
 class LoadStoreUnitInterface:
     def __init__(self, addr_wid=32, mask_wid=4, data_wid=32):
         self.dbus = Record(wishbone_layout)
-
-        self.x_addr = Signal(addr_wid)
-        self.x_mask = Signal(mask_wid)
-        self.x_load = Signal()
-        self.x_store = Signal()
-        self.x_store_data = Signal(data_wid)
-        self.x_stall = Signal()
+        badwid = addr_wid-log2_int(mask_wid) # TODO: is this correct?
+
+        self.x_addr = Signal(addr_wid) # The address used for loads/stores
+        self.x_mask = Signal(mask_wid) # Mask of which bytes to write
+        self.x_load = Signal()         # set to do a memory load
+        self.x_store = Signal()        # set to do a memory store
+        self.x_store_data = Signal(data_wid) # The data to write when storing
+        self.x_stall = Signal()        # input - do nothing until low
         self.x_valid = Signal()
-        self.m_stall = Signal()
-        self.m_valid = Signal()
-
-        self.x_busy = Signal()
-        self.m_busy = Signal()
-        self.m_load_data = Signal(data_wid)
-        self.m_load_error = Signal()
-        self.m_store_error = Signal()
-        self.m_badaddr = Signal(addr_wid-log2_int(mask_wid))
+        self.m_stall = Signal()        # input - do nothing until low
+        self.m_valid = Signal()        # when this is high and m_busy is
+                                       # low, the data for the memory load
+                                       # can be read from m_load_data
+
+        self.x_busy = Signal()         # set when the memory is busy
+        self.m_busy = Signal()         # set when the memory is busy
+        self.m_load_data = Signal(data_wid) # Data returned from a memory read
+        self.m_load_error = Signal()   # Whether there was an error when loading
+        self.m_store_error = Signal()  # Whether there was an error when storing
+        self.m_badaddr = Signal(badwid) # The address of the load/store error
 
 
 class BareLoadStoreUnit(LoadStoreUnitInterface, Elaboratable):