From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Wed, 2 Jun 2021 13:34:52 +0000 (+0100)
Subject: found FP single-conversion error, from the pseudocode, incorrectly
X-Git-Tag: xlen-bcd~487
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=911645bdd72f91908cd298b2789ef2eb468a791b;p=openpower-isa.git

found FP single-conversion error, from the pseudocode, incorrectly
translated to python by hand.  really should replace it with actual
pseudocode
---

diff --git a/src/openpower/decoder/helpers.py b/src/openpower/decoder/helpers.py
index 7e83faef..db7ef6da 100644
--- a/src/openpower/decoder/helpers.py
+++ b/src/openpower/decoder/helpers.py
@@ -174,22 +174,22 @@ def DOUBLE(WORD):
         FRT[4] = ~WORD[1]
         FRT[5:64] = selectconcat(WORD[2:32], z29)
 
-    # Denormalized Operand
-    if e.value  == 0 and m.value != 0:
-        log ("denormalised")
-        sign = WORD[0]
-        exp = -126
-        frac = selectconcat(z1, WORD[9:32], z29)
-        # normalize the operand
-        while frac[0].value  == 0:
-            frac[0:53] = selectconcat(frac[1:53], z1)
-            exp = exp - 1
-        FRT[0] = sign
-        FRT[1:12] = exp + 1023
-        FRT[12:64] = frac[1:53]
+        # Denormalized Operand
+        if e.value  == 0 and m.value != 0:
+            log ("denormalised")
+            sign = WORD[0]
+            exp = -126
+            frac = selectconcat(z1, WORD[9:32], z29)
+            # normalize the operand
+            while frac[0].value  == 0:
+                frac[0:53] = selectconcat(frac[1:53], z1)
+                exp = exp - 1
+            FRT[0] = sign
+            FRT[1:12] = exp + 1023
+            FRT[12:64] = frac[1:53]
 
     # Zero / Infinity / NaN
-    if e.value  == 255 or m.value  == 0:
+    if e.value  == 255 or WORD[1:32].value  == 0:
         log ("z/inf/nan")
         FRT[0:2] = WORD[0:2]
         FRT[2] = WORD[1]
diff --git a/src/openpower/decoder/isa/test_caller_fp.py b/src/openpower/decoder/isa/test_caller_fp.py
index 3d8fdfa9..5e745ef4 100644
--- a/src/openpower/decoder/isa/test_caller_fp.py
+++ b/src/openpower/decoder/isa/test_caller_fp.py
@@ -38,6 +38,21 @@ class DecoderTestCase(FHDLTestCase):
             print("FPR 1", sim.fpr(1))
             self.assertEqual(sim.fpr(1), SelectableInt(0x4040266660000000, 64))
 
+    def test_fpload2(self):
+        """>>> lst = ["lfsx 1, 0, 0",
+                     ]
+        """
+        lst = ["lfsx 1, 0, 0",
+                     ]
+        initial_mem = {0x0000: (0xac000000, 8),
+                       0x0020: (0x1828384822324252, 8),
+                        }
+
+        with Program(lst, bigendian=False) as program:
+            sim = self.run_tst_program(program, initial_mem=initial_mem)
+            print("FPR 1", sim.fpr(1))
+            self.assertEqual(sim.fpr(1), SelectableInt(0xbd80000000000000, 64))
+
     def test_fp_single_ldst(self):
         """>>> lst = ["lfsx 1, 1, 0",   # load fp 1 from mem location 0
                       "stfsu 1, 16(1)", # store fp 1 into mem 0x10, update RA