From 4b7c6f6e5fab83021e75cb8306b081b4cbc7d3af Mon Sep 17 00:00:00 2001
From: Jakob Kaivo <jkk@ung.org>
Date: Mon, 28 Mar 2022 14:53:47 -0400
Subject: modernize longdiv()

---
 big.c | 65 +++++++++++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 43 insertions(+), 22 deletions(-)

(limited to 'big.c')

diff --git a/big.c b/big.c
index 806cd11..9f195d3 100644
--- a/big.c
+++ b/big.c
@@ -478,48 +478,69 @@ word shortdiv(word x, word n)
   return q;
 }
 
-word longdiv(x, y)		/* divide big x by big y returning quotient, leaving
-				   remainder in extern variable b_rem */
- /* may assume - x>=0,y>0 */
-word x, y;
+/* divide big x by big y returning quotient, leaving
+   remainder in extern variable b_rem */
+/* may assume - x>=0,y>0 */
+word longdiv(word x, word y)
 {
-  word n, q, ly, y1, scale;
   if (bigcmp(x, y) < 0) {
     b_rem = x;
     return (make(INT, 0, 0));
   }
-  y1 = msd(y);
-  if ((scale = IBASE / (y1 + 1)) > 1)	/* rescale if necessary */
-    x = stimes(x, scale), y = stimes(y, scale), y1 = msd(y);
-  n = q = 0;
-  ly = len(y);
-  while (bigcmp(x, y = make(INT, 0, y)) >= 0)
+
+  word y1 = msd(y);
+
+  /* rescale if necessary */
+  word scale = IBASE / (y1 + 1);
+  if (scale > 1) {
+    x = stimes(x, scale);
+    y = stimes(y, scale);
+    y1 = msd(y);
+  }
+
+  word n = 0;
+  word q = 0;
+  word ly = len(y);
+  while (bigcmp(x, y = make(INT, 0, y)) >= 0) {
     n++;
+  }
+
   y = rest(y);			/* want largest y not exceeding x */
   ly += n;
   for (;;) {
     word d, lx = len(x);
-    if (lx < ly)
+    if (lx < ly) {
       d = 0;
-    else if (lx == ly)
-      if (bigcmp(x, y) >= 0)
-	x = bigsub(x, y), d = 1;
-      else
+
+    } else if (lx == ly) {
+      if (bigcmp(x, y) >= 0) {
+	x = bigsub(x, y);
+        d = 1;
+      } else {
 	d = 0;
-    else {
+      }
+
+    } else {
       d = ms2d(x) / y1;
-      if (d > MAXDIGIT)
+      if (d > MAXDIGIT) {
 	d = MAXDIGIT;
-      if ((d -= 2) > 0)
+      }
+
+      if ((d -= 2) > 0) {
 	x = bigsub(x, stimes(y, d));
-      else
+      } else {
 	d = 0;
+      }
+
       if (bigcmp(x, y) >= 0) {
 	x = bigsub(x, y), d++;
-	if (bigcmp(x, y) >= 0)
-	  x = bigsub(x, y), d++;
+	if (bigcmp(x, y) >= 0) {
+	  x = bigsub(x, y);
+          d++;
+        }
       }
     }
+
     q = make(INT, d, q);
     if (n-- == 0) {
       b_rem = scale == 1 ? x : shortdiv(x, scale);
-- 
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