From fc018f79368c9c2969e2f5fc29befaa99b1d43c3 Mon Sep 17 00:00:00 2001
From: Dmitry Selyutin <ghostmansd@gmail.com>
Date: Sun, 15 Jan 2023 11:35:18 +0300
Subject: [PATCH] pysvp64dis: do not create temporary bytes upon load

---
 src/openpower/sv/trans/pysvp64dis.py      | 12 ++----------
 src/openpower/sv/trans/test_pysvp64dis.py |  7 ++++++-
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/src/openpower/sv/trans/pysvp64dis.py b/src/openpower/sv/trans/pysvp64dis.py
index 3722af09..64ef66ec 100644
--- a/src/openpower/sv/trans/pysvp64dis.py
+++ b/src/openpower/sv/trans/pysvp64dis.py
@@ -2,7 +2,6 @@ import argparse as _argparse
 import enum as _enum
 import sys as _sys
 import os as _os
-from io import BytesIO
 
 from openpower.decoder.power_enums import (
     find_wiki_dir as _find_wiki_dir,
@@ -27,13 +26,8 @@ class ByteOrder(_enum.Enum):
 def load(ifile, byteorder=ByteOrder.LITTLE, **_):
     byteorder = str(byteorder)
 
-    # copy over to persistent binfile (BytesIO)
-    cpfile = BytesIO()
-    cpfile.write(ifile.read())
-    cpfile.seek(0)
-
     while True:
-        insn = cpfile.read(4)
+        insn = ifile.read(4)
         length = len(insn)
         if length == 0:
             return
@@ -41,7 +35,7 @@ def load(ifile, byteorder=ByteOrder.LITTLE, **_):
             raise IOError(insn)
         insn = _WordInstruction.integer(value=insn, byteorder=byteorder)
         if insn.PO == 0x1:
-            suffix = cpfile.read(4)
+            suffix = ifile.read(4)
             length = len(suffix)
             if length == 0:
                 yield insn
@@ -56,8 +50,6 @@ def load(ifile, byteorder=ByteOrder.LITTLE, **_):
                 insn = _PrefixedInstruction.pair(prefix=prefix, suffix=suffix)
         yield insn
 
-    cpfile.seek(0) # restore position so that generator can be reused
-
 
 def dump(insns, verbosity, **_):
     db = _Database(_find_wiki_dir())
diff --git a/src/openpower/sv/trans/test_pysvp64dis.py b/src/openpower/sv/trans/test_pysvp64dis.py
index d39717e2..dedf12ae 100644
--- a/src/openpower/sv/trans/test_pysvp64dis.py
+++ b/src/openpower/sv/trans/test_pysvp64dis.py
@@ -5,6 +5,7 @@ from openpower.decoder.power_insn import Database, Verbosity
 from openpower.decoder.power_enums import find_wiki_dir
 from openpower.sv import sv_binutils_fptrans
 import unittest
+from io import BytesIO
 import itertools
 import sys
 
@@ -15,8 +16,12 @@ class SVSTATETestCase(unittest.TestCase):
         lst = list(isa)
         with Program(lst, bigendian=False) as program:
             print ("ops", program._instructions)
+            binfile = BytesIO()
             program.binfile.seek(0)
-            insns = load(program.binfile)
+            binfile.write(program.binfile.read())
+            program.binfile.seek(0)
+            binfile.seek(0)
+            insns = load(binfile)
             #for insn in insns:
                 #print ("insn", insn)
             insns = list(insns)
-- 
2.30.2