From 95637dea751a72a02897a8f76743c15038d97b46 Mon Sep 17 00:00:00 2001
From: Jonas Maebe <jonas@freepascal.org>
Date: Tue, 29 Apr 2008 22:14:43 +0000
Subject: [PATCH]   * fixed swapendian(smallint) (bug found by Joost van der
 Sluis)   * based swap(smallint) and swap(word) on swapendian(smallint/word), 
    since the same bug was already fixed in swap(smallint) in r6752     (so
 these routines now share the same code)   * fixed potential range error in
 swapendian(word)   + added basic test for the above four routines

git-svn-id: trunk@10840 -
---
 .gitattributes      |  1 +
 rtl/inc/generic.inc |  8 ++++++--
 rtl/inc/system.inc  | 12 ++++--------
 tests/tbs/tb0548.pp | 30 ++++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+), 10 deletions(-)
 create mode 100644 tests/tbs/tb0548.pp

diff --git a/.gitattributes b/.gitattributes
index 98dd68e3ec..b3bd547b9a 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -6834,6 +6834,7 @@ tests/tbs/tb0544.pp svneol=native#text/plain
 tests/tbs/tb0545.pp svneol=native#text/plain
 tests/tbs/tb0546.pp svneol=native#text/plain
 tests/tbs/tb0547.pp svneol=native#text/plain
+tests/tbs/tb0548.pp svneol=native#text/plain
 tests/tbs/tb205.pp svneol=native#text/plain
 tests/tbs/ub0060.pp svneol=native#text/plain
 tests/tbs/ub0069.pp svneol=native#text/plain
diff --git a/rtl/inc/generic.inc b/rtl/inc/generic.inc
index dc9e15d15e..e583e2dcf8 100644
--- a/rtl/inc/generic.inc
+++ b/rtl/inc/generic.inc
@@ -1707,13 +1707,17 @@ end;
 {$ifndef FPC_SYSTEM_HAS_SWAPENDIAN}
 function SwapEndian(const AValue: SmallInt): SmallInt;
   begin
-    Result := (AValue shr 8) or (AValue shl 8);
+    { the extra Word type cast is necessary because the "AValue shr 8" }
+    { is turned into "longint(AValue) shr 8", so if AValue < 0 then    }
+    { the sign bits from the upper 16 bits are shifted in rather than  }
+    { zeroes.                                                          }
+    Result := SmallInt((Word(AValue) shr 8) or (AValue shl 8));
   end;
 
 
 function SwapEndian(const AValue: Word): Word;
   begin
-    Result := (AValue shr 8) or (AValue shl 8);
+    Result := Word((AValue shr 8) or (AValue shl 8));
   end;
 
 
diff --git a/rtl/inc/system.inc b/rtl/inc/system.inc
index 0ea21316f6..b3163e1644 100644
--- a/rtl/inc/system.inc
+++ b/rtl/inc/system.inc
@@ -245,21 +245,17 @@ begin
    Lo := b and $0f
 end;
 
-Function swap (X : Word) : Word;{$ifdef SYSTEMINLINE}inline;{$endif}
+Function Swap (X : Word) : Word;{$ifdef SYSTEMINLINE}inline;{$endif}
 Begin
-  swap:=(X and $ff) shl 8 + (X shr 8)
+  Swap := SwapEndian(X);
 End;
 
 Function Swap (X : Integer) : Integer;{$ifdef SYSTEMINLINE}inline;{$endif}
 Begin
-  { the extra 'and $ff' in the right term is necessary because the  }
-  { 'X shr 8' is turned into "longint(X) shr 8", so if x < 0 then   }
-  { the sign bits from the upper 16 bits are shifted in rather than }
-  { zeroes. Another bug for TP/Delphi compatibility...              }
-  swap:=(X and $ff) shl 8 + ((X shr 8) and $ff)
+  Swap := SwapEndian(X);
 End;
 
-Function swap (X : Longint) : Longint;{$ifdef SYSTEMINLINE}inline;{$endif}
+Function Swap (X : Longint) : Longint;{$ifdef SYSTEMINLINE}inline;{$endif}
 Begin
   Swap:=(X and $ffff) shl 16 + (X shr 16)
 End;
diff --git a/tests/tbs/tb0548.pp b/tests/tbs/tb0548.pp
new file mode 100644
index 0000000000..750442d1a9
--- /dev/null
+++ b/tests/tbs/tb0548.pp
@@ -0,0 +1,30 @@
+{$r+}
+{$q+}
+
+var
+  wo: word;
+  si: smallint;
+
+begin
+  wo:=$9876;
+  if swap(wo)<>$7698 then
+    halt(1);
+  if swapendian(wo)<>$7698 then
+    halt(2);
+  wo:=$1290;
+  if swap(wo)<>$9012 then
+    halt(3);
+  if swapendian(wo)<>$9012 then
+    halt(4);
+
+  si:=smallint($9876);
+  if swap(si)<>$7698 then
+    halt(5);
+  if swapendian(si)<>$7698 then
+    halt(6);
+  si:=$1290;
+  if swap(si)<>smallint($9012) then
+    halt(7);
+  if swapendian(si)<>smallint($9012) then
+    halt(8);
+end.