From 58b0dd07d7214f9cdbc7d1f22389dd6c35191907 Mon Sep 17 00:00:00 2001
From: "Guillermo J. Rozas" <edu/mit/csail/zurich/gjr>
Date: Fri, 18 Sep 1992 16:52:34 +0000
Subject: [PATCH] Add ulong_to_bignum and bignum_to_ulong.

---
 v7/src/microcode/bignum.c | 45 ++++++++++++++++++++++++++++++++++++++-
 v7/src/microcode/bignum.h |  4 +++-
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/v7/src/microcode/bignum.c b/v7/src/microcode/bignum.c
index c60190ff2..47c353c50 100644
--- a/v7/src/microcode/bignum.c
+++ b/v7/src/microcode/bignum.c
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: bignum.c,v 9.37 1992/08/29 13:34:08 jinx Exp $
+$Id: bignum.c,v 9.38 1992/09/18 16:52:22 jinx Exp $
 
 Copyright (c) 1989-1992 Massachusetts Institute of Technology
 
@@ -495,6 +495,49 @@ DEFUN (bignum_to_long, (bignum), bignum_type bignum)
   }
 }
 
+bignum_type
+DEFUN (ulong_to_bignum, (n), unsigned long n)
+{
+  bignum_digit_type result_digits [BIGNUM_DIGITS_FOR_LONG];
+  fast bignum_digit_type * end_digits = result_digits;
+  /* Special cases win when these small constants are cached. */
+  if (n == 0) return (BIGNUM_ZERO ());
+  if (n == 1) return (BIGNUM_ONE (0));
+  {
+    fast unsigned long accumulator = n;
+    do
+      {
+	(*end_digits++) = (accumulator & BIGNUM_DIGIT_MASK);
+	accumulator >>= BIGNUM_DIGIT_LENGTH;
+      }
+    while (accumulator != 0);
+  }
+  {
+    bignum_type result =
+      (bignum_allocate ((end_digits - result_digits), 0));
+    fast bignum_digit_type * scan_digits = result_digits;
+    fast bignum_digit_type * scan_result = (BIGNUM_START_PTR (result));
+    while (scan_digits < end_digits)
+      (*scan_result++) = (*scan_digits++);
+    return (result);
+  }
+}
+
+unsigned long
+DEFUN (bignum_to_ulong, (bignum), bignum_type bignum)
+{
+  if (BIGNUM_ZERO_P (bignum))
+    return (0);
+  {
+    fast unsigned long accumulator = 0;
+    fast bignum_digit_type * start = (BIGNUM_START_PTR (bignum));
+    fast bignum_digit_type * scan = (start + (BIGNUM_LENGTH (bignum)));
+    while (start < scan)
+      accumulator = ((accumulator << BIGNUM_DIGIT_LENGTH) + (*--scan));
+    return (accumulator);
+  }
+}
+
 #endif /* not BIGNUM_NO_ULONG */
 
 #define DTB_WRITE_DIGIT(factor)						\
diff --git a/v7/src/microcode/bignum.h b/v7/src/microcode/bignum.h
index 6ab939c07..8ae9040e6 100644
--- a/v7/src/microcode/bignum.h
+++ b/v7/src/microcode/bignum.h
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/microcode/bignum.h,v 9.27 1992/02/10 13:16:02 jinx Exp $
+$Id: bignum.h,v 9.28 1992/09/18 16:52:34 jinx Exp $
 
 Copyright (c) 1989-1992 Massachusetts Institute of Technology
 
@@ -78,7 +78,9 @@ extern bignum_type EXFUN (bignum_quotient, (bignum_type, bignum_type));
 extern bignum_type EXFUN (bignum_remainder, (bignum_type, bignum_type));
 #ifndef BIGNUM_NO_ULONG
 extern bignum_type EXFUN (long_to_bignum, (long));
+extern bignum_type EXFUN (ulong_to_bignum, (unsigned long));
 extern long EXFUN (bignum_to_long, (bignum_type));
+extern unsigned long EXFUN (bignum_to_ulong, (bignum_type));
 #endif /* not BIGNUM_NO_ULONG */
 extern bignum_type EXFUN (double_to_bignum, (double));
 extern double EXFUN (bignum_to_double, (bignum_type));
-- 
2.25.1