From 85f82a22d40942a8a8cfe3a1b0e8432a66fc5e89 Mon Sep 17 00:00:00 2001
From: vsc <vsc@b08c6af1-5177-4d33-ba66-4b1c6b8b522a>
Date: Mon, 4 Jun 2007 12:11:47 +0000
Subject: [PATCH] fix interface bug with external c-code.

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1893 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
---
 C/exec.c         | 12 +++++++++++-
 changes-5.1.html |  1 +
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/C/exec.c b/C/exec.c
index 4335f927f..f75ed3e9f 100644
--- a/C/exec.c
+++ b/C/exec.c
@@ -747,7 +747,17 @@ p_execute_nonstop(void)
     return CallPredicate(RepPredProp(pe), B, RepPredProp(pe)->cs.p_code.TrueCodeOfPred);
   }  else if ((RepPredProp(pe)->PredFlags & (AsmPredFlag|CPredFlag)) &&
 	      RepPredProp(pe)->OpcodeOfPred != Yap_opcode(_call_bfunc_xx)) {
-    return RepPredProp(pe)->cs.f_code();
+    /* USER C-Code may walk over registers */
+    if (RepPredProp(pe)->PredFlags & UserCPredFlag) {
+      save_machine_regs();
+    }
+    if (RepPredProp(pe)->PredFlags & UserCPredFlag) {
+      Int out = RepPredProp(pe)->cs.f_code();
+      restore_machine_regs();
+      return out;
+    } else {
+      return RepPredProp(pe)->cs.f_code();
+    }
   } else {
     return CallPredicate(RepPredProp(pe), B, RepPredProp(pe)->CodeOfPred);
   }
diff --git a/changes-5.1.html b/changes-5.1.html
index cbee20276..46e767127 100644
--- a/changes-5.1.html
+++ b/changes-5.1.html
@@ -16,6 +16,7 @@
 
 <h2>Yap-5.1.2:</h2>
 <ul>
+<li> FIXED: bug in meta-calls to external C code (obs from Bernd Gutmann).</li>
 <li> NEW: matlab interface.</li>
 <li> FIXED: search for libraries right.</li>
 <li> FIXED: alarm used alarm(2) but it should use setitimer(2) so that