From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Fri, 22 Dec 2023 09:11:58 +0000 (+0000)
Subject: bug 1155: split out yielding indices into separate function
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=aa6f10d1f2;p=openpower-isa.git

bug 1155: split out yielding indices into separate function

when done as a separate "yielding function" this is closer to the hardware
and is a code-morph step to putting that (very same) yielding function
behind the SVSHAPE system in ISACaller
---

diff --git a/src/openpower/test/bigint/powmod.py b/src/openpower/test/bigint/powmod.py
index 13c092e8..6ceb9f7f 100644
--- a/src/openpower/test/bigint/powmod.py
+++ b/src/openpower/test/bigint/powmod.py
@@ -99,28 +99,25 @@ def python_mul_algorithm(a, b):
     return y
 
 
-def python_mul_remap_algorithm(a, b):
-    # version 2 of the MUL_256_X_256_TO_512_ASM algorithm using base 100 rather
-    # than 2^64, since that's easier to read.
-    a_sz, b_sz = len(a), = len(b)
-    ai, bi, apbi, apbp1 = [], [], [], [] # REMAP indices
+def python_mul_remap_yielder(a_sz, b_sz):
     for ai in range(a_sz):
         for bi in range(b_sz):
-            ai.append(ai)
-            bi.append(bi)
-            apbi.append(ai + bi)
-            apbp1.append(ai + bi + 1)
+            yield ai, bi, ai + bi, ai + bi + 1
 
+def python_mul_remap_algorithm(a, b):
+    # version 2 of the MUL_256_X_256_TO_512_ASM algorithm using base 100 rather
+    # than 2^64, since that's easier to read.
+    a_sz, b_sz = len(a), len(b)
     y = [0] * (a_sz + b_sz)
     ca = 0
-    for i in range(a_sz * b_sz):
+    for ai, bi, apbi, apbp1 in python_mul_remap_yielder(a_sz, b_sz):
         # no need to clear ca between ai outer loops, since the partial
         # products can't get big enough to have a carry out, so ca will
         # always be zero when (i % b_sz == 0).
         # That said, hardware will probably want to pattern-match this to
         # remove the unnecessary dependency through ca.
-        y[apbi[i]], t = maddedu(a[ai[i]], b[bi[i]], y[apbi[i]])
-        y[apbp1[i]], ca = adde(y[apbp1[i]], t, ca)
+        y[apbi], t = maddedu(a[ai], b[bi], y[apbi])
+        y[apbp1], ca = adde(y[apbp1], t, ca)
     return y