add wb_get function for emulating wishbone interface

diff --git a/src/openpower/test/wb_get.py b/src/openpower/test/wb_get.py
new file mode 100644 (file)
index 0000000..4d8a098
--- /dev/null
+++ b/src/openpower/test/wb_get.py
@@ -0,0 +1,52 @@
+"""useful function for emulating a wishbone interface
+"""
+
+stop = False
+
+def wb_get(wb, mem):
+    """simulator process for getting memory load requests
+    """
+
+    global stop
+    assert (stop == False)
+
+    while not stop:
+        while True: # wait for dc_valid
+            if stop:
+                return
+            cyc = yield (wb.cyc)
+            stb = yield (wb.stb)
+            if cyc and stb:
+                break
+            yield
+        addr = (yield wb.adr) << 3
+        if addr not in mem:
+            print ("    WB LOOKUP NO entry @ %x, returning zero" % (addr))
+
+        # read or write?
+        we = (yield wb.we)
+        if we:
+            store = (yield wb.dat_w)
+            sel = (yield wb.sel)
+            data = mem.get(addr, 0)
+            # note we assume 8-bit sel, here
+            res = 0
+            for i in range(8):
+                mask = 0xff << (i*8)
+                if sel & (1<<i):
+                    res |= store & mask
+                else:
+                    res |= data & mask
+            mem[addr] = res
+            print ("    DCACHE set %x mask %x data %x" % (addr, sel, res))
+        else:
+            data = mem.get(addr, 0)
+            yield wb.dat_r.eq(data)
+            print ("    DCACHE get %x data %x" % (addr, data))
+
+        yield wb.ack.eq(1)
+        yield
+        yield wb.ack.eq(0)
+        yield
+
+