From a1fc933c3dd4581f2994b6e720fad332a4b56b68 Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Mon, 6 Jul 2020 20:19:58 +0100
Subject: [PATCH] add MULS (signed) version of multiply

---
 src/soc/decoder/helpers.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/soc/decoder/helpers.py b/src/soc/decoder/helpers.py
index 53edaca2..8cab8d50 100644
--- a/src/soc/decoder/helpers.py
+++ b/src/soc/decoder/helpers.py
@@ -27,6 +27,17 @@ def EXTS64(value):
     return SelectableInt(exts(value.value, value.bits) & ((1 << 64)-1), 64)
 
 
+# signed version of MUL
+def MULS(a, b):
+    a_s = a.value & (1<<(a.bits-1)) != 0
+    b_s = b.value & (1<<(b.bits-1)) != 0
+    result = abs(a) * abs(b)
+    print ("MULS", result, a_s, b_s)
+    if a_s == b_s:
+        return result
+    return -result
+
+
 # XXX should this explicitly extend from 32 to 64?
 def EXTZ64(value):
     if isinstance(value, SelectableInt):
-- 
2.30.2