From babe6af16740f3fa3c19ef4b689f29d574c5fbc8 Mon Sep 17 00:00:00 2001
From: Alexei Podtelezhnikov <apodtele@gmail.com>
Date: Mon, 18 Sep 2023 15:01:26 +0000
Subject: [PATCH] * src/base/ftcalc.c /* FT_SqrtFixed */: Fix defunct overflow.

---
 src/base/ftcalc.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/base/ftcalc.c b/src/base/ftcalc.c
index ba4d5e3fd..0b915992a 100644
--- a/src/base/ftcalc.c
+++ b/src/base/ftcalc.c
@@ -917,17 +917,18 @@
 
   /* documentation is in ftcalc.h */
 
-  /* Algorithm and code by Christophe Meessen (1993). */
+  /* Algorithm and code by Christophe Meessen (1993) */ 
+  /* with overflow fixed.                            */
   FT_BASE_DEF( FT_UInt32 )
-  FT_SqrtFixed( FT_UInt32  r )
+  FT_SqrtFixed( FT_UInt32  v )
   {
-    FT_UInt32  t, q, b;
+    FT_UInt32  r = v >> 1;
+    FT_UInt32  q = ( v & 1 ) << 15;
+    FT_UInt32  b = 0x20000000;
+    FT_UInt32  t;
 
 
-    q = 0;
-
-    b = 0x40000000;
-    while ( b > 0x40 )
+    do
     {
       t = q + b;
       if ( r >= t )
@@ -938,8 +939,9 @@
       r <<= 1;
       b >>= 1;
     }
+    while ( b > 0x20 );
 
-    return q >> 8;
+    return q >> 7;
   }
 
 #endif /* 0 */