From: Chris Hanson <org/chris-hanson/cph>
Date: Mon, 6 Mar 1995 21:45:34 +0000 (+0000)
Subject: Fix stupid bug in `copy_bits': code to generate mask was doing
X-Git-Tag: 20090517-FFI~6563
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=ccbd9b3bf61c17bc1f7e9226f7fe2ab690e62862;p=mit-scheme.git

Fix stupid bug in `copy_bits': code to generate mask was doing

    ((1 << 32) - 1)

and expecting something reasonable to happen on a 32-bit machine.
---

diff --git a/v7/src/microcode/bitstr.c b/v7/src/microcode/bitstr.c
index 4e3a0c50e..251ac07cf 100644
--- a/v7/src/microcode/bitstr.c
+++ b/v7/src/microcode/bitstr.c
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: bitstr.c,v 9.54 1995/01/25 20:54:55 cph Exp $
+$Id: bitstr.c,v 9.55 1995/03/06 21:45:34 cph Exp $
 
 Copyright (c) 1987-95 Massachusetts Institute of Technology
 
@@ -508,10 +508,13 @@ DEFUN (copy_bits,
 	  {
 	    long mask = (ANY_MASK (head, offset1));
 	    dest_buffer
-	      = (((BIT_STRING_WORD (destination))
-		  &~ (LOW_MASK (head + offset1)))
-		 | (((* (DEC_BIT_STRING_PTR (source))) & (LOW_MASK (head)))
-		    << offset1));
+	      = (((head + offset1) < OBJECT_LENGTH)
+		 ? ((BIT_STRING_WORD (destination))
+		    &~ (LOW_MASK (head + offset1)))
+		 : 0);
+	    dest_buffer
+	      |= (((* (DEC_BIT_STRING_PTR (source))) & (LOW_MASK (head)))
+		  << offset1);
 	  }
 	  nbits -= head;
 	  while (nbits >= OBJECT_LENGTH)