This patch adds a mechanism to suppress ERC errors and warnings that
are caused by pins incompatibilities. It works by loading a file with
ERC exceptions each time an ERC is performed and then looking for an
entry before issuing a warning or error.

The file has the same path and name as the .sch file, but ends in .erx
(Electric Rule eXceptions). Each line contains the following four
whitespace-separated fields:

- component reference of the first component 
- pin number of the first component 
- component reference of the second component 
- pin number of the second component 

# is used as a comment character. Note that the file is reloaded
each time ERC is invoked, so one can edit it in parallel to
running eeschema.

Known bug: ERC dialog window needs reformatting for displaying the
exception count.

The patch needs to be applied on top of the TestOthersItems
streamlining patch.

- Werner

Updated to rev 1923

- Nathael

---

Index: kicad/eeschema/erc.cpp
===================================================================
--- kicad.orig/eeschema/erc.cpp	2010-04-28 05:40:38.000000000 -0300
+++ kicad/eeschema/erc.cpp	2010-04-28 05:49:35.000000000 -0300
@@ -4,6 +4,7 @@
 
 #include "fctsys.h"
 #include "common.h"
+#include "confirm.h"
 #include "class_drawpanel.h"
 #include "kicad_string.h"
 #include "gestfich.h"
@@ -230,6 +231,173 @@
 }
 
 
+static struct exception
+{
+    char* a_ref;
+    char* a_pin;
+    char* b_ref;
+    char* b_pin;
+    char* line; /* pointer to the memory object we've allocated */
+    struct exception* next;
+}* exceptions;
+
+
+
+static void FreeExceptions( void )
+{
+    struct exception* next;
+
+    while( exceptions )
+    {
+        next = exceptions->next;
+        MyFree( exceptions->line );
+        MyFree( exceptions );
+        exceptions = next;
+    }
+}
+
+
+static bool ParseField( char **s, char **field )
+{
+    *field = *s;
+    if( ! **s )
+        return FALSE;
+    while( **s && ! isspace( **s ) )
+        (*s)++;
+    if( ! **s )
+        return TRUE;
+    *(*s)++ = 0;
+    while( **s && isspace( **s ) )
+        (*s)++;
+    return TRUE;
+}
+
+
+static bool ParseException( char *s )
+{
+    struct exception tmp;
+    struct exception* e;
+
+    tmp.line = s;
+
+    if( ! ParseField( &s, &tmp.a_ref))
+        return FALSE;
+    if( ! ParseField( &s, &tmp.a_pin ))
+        return FALSE;
+    if( ! ParseField( &s, &tmp.b_ref))
+        return FALSE;
+    if( ! ParseField( &s, &tmp.b_pin ))
+        return FALSE;
+
+    e = (struct exception*) MyMalloc( sizeof( *e ));
+    *e = tmp;
+    e->next = exceptions;
+    exceptions = e;
+
+    return TRUE;
+}
+
+
+static bool LoadExceptionsByName( const wxString &file_name )
+{
+    FILE* file;
+    char buf[200]; /* enough room for chatty comments */
+    char* s;
+    char* tmp;
+    char* hash;
+    int n = 0;
+
+    FreeExceptions();
+    file = wxFopen( file_name, wxT( "r" ) );
+    if( ! file )
+        return FALSE;
+
+    while( 1 )
+    {
+        s = fgets( buf, sizeof( buf ), file );
+        if( ! s )
+            break;
+
+        n++;
+
+        // remove comments
+        hash = strchr( s, '#' );
+        if( hash )
+            *hash = 0;
+
+        // skip leading whitespace
+        while( *s && isspace( *s ) )
+            s++;
+        if( ! *s )
+            continue;
+
+        tmp = (char*) MyMalloc( strlen( s ) + 1 );
+        strcpy( tmp, s );
+
+        if( ! ParseException( tmp ) )
+        {
+            wxString msg;
+
+            msg.Printf( wxT( "Parse error at %s:%d" ), CONV_TO_UTF8(file_name), n );
+            DisplayError( NULL, msg );
+            MyFree( tmp );
+            break;
+        }
+    }
+
+    fclose( file );
+
+    return TRUE;
+}
+
+
+static void LoadExceptions( void )
+{
+    wxFileName fn;
+
+    fn = g_RootSheet->m_AssociatedScreen->m_FileName;
+    fn.SetExt( wxT( "erx" ) );
+    if ( LoadExceptionsByName( fn.GetFullPath() ) )
+        g_EESchemaVar.NbExceptionErc = 0;
+}
+
+
+static bool FindException( NETLIST_OBJECT* a, NETLIST_OBJECT* b )
+{
+    SCH_COMPONENT* a_comp = (SCH_COMPONENT*) a->m_Link;
+    SCH_COMPONENT* b_comp = (SCH_COMPONENT*) b->m_Link;
+    const char* a_ref = CONV_TO_UTF8( a_comp->GetRef( &a->m_SheetList ) );
+    const char* b_ref = CONV_TO_UTF8( b_comp->GetRef( &b->m_SheetList ) );
+    const char* a_pin = (char *) &a->m_PinNum;
+    const char* b_pin = (char *) &b->m_PinNum;
+    struct exception* e = exceptions;
+
+    for( e = exceptions; e; e = e->next )
+    {
+#if 0
+fprintf(stderr, "a) %s %4.4s =? %s %4.4s\n", e->a_ref, e->a_pin, a_ref, a_pin);
+fprintf(stderr, "b) %s %4.4s =? %s %4.4s\n", e->b_ref, e->b_pin, b_ref, b_pin);
+#endif
+        if( strcmp( e->a_ref, a_ref ) )
+            continue;
+        if( strncmp( e->a_pin, a_pin, 4 ) )
+            continue;
+        if( strcmp( e->b_ref, b_ref ) )
+            continue;
+        if( strncmp( e->b_pin, b_pin, 4 ) )
+            continue;
+        return TRUE;
+    }
+    return FALSE;
+}
+
+
+static bool IsException( NETLIST_OBJECT* a, NETLIST_OBJECT* b )
+{
+    return FindException( a, b ) || FindException( b, a);
+}
+
+
 void DIALOG_ERC::TestErc( wxArrayString* aMessagesList )
 {
     wxFileName fn;
@@ -264,6 +432,7 @@
 
     g_EESchemaVar.NbErrorErc   = 0;
     g_EESchemaVar.NbWarningErc = 0;
+    g_EESchemaVar.NbExceptionErc = -1; /* -1 means "no file" */
 
     /* Cleanup the entire hierarchy */
     EDA_ScreenList ScreenList;
@@ -290,6 +459,8 @@
 
     m_Parent->BuildNetListBase();
 
+    LoadExceptions();
+
     /* Reset the flag m_FlagOfConnection, that will be used next, in
      * calculations */
     for( unsigned ii = 0; ii < g_NetObjectslist.size(); ii++ )
@@ -358,7 +529,13 @@
 
     // Displays global results:
     wxString num;
-    num.Printf( wxT( "%d" ), g_EESchemaVar.NbErrorErc );
+
+    if( g_EESchemaVar.NbExceptionErc >= 0)
+        num.Printf( wxT( "%d (%d exception%s)" ), g_EESchemaVar.NbErrorErc,
+          g_EESchemaVar.NbExceptionErc,
+          g_EESchemaVar.NbExceptionErc == 1 ? wxT( "" ) : wxT( "s" ) );
+    else
+        num.Printf( wxT( "%d" ), g_EESchemaVar.NbErrorErc );
     m_TotalErrCount->SetLabel( num );
 
     num.Printf( wxT(
@@ -662,6 +839,12 @@
             if( g_NetObjectslist[NetItemTst]->m_FlagOfConnection != 0 )
 		break;
 
+		if( IsException( g_NetObjectslist[NetItemRef], g_NetObjectslist[NetItemTst] ) )
+		{
+		    g_EESchemaVar.NbExceptionErc++;
+		    break;
+		}
+
             Diagnose( panel,
                       g_NetObjectslist[NetItemRef],
                       g_NetObjectslist[NetItemTst],
Index: kicad/eeschema/general.h
===================================================================
--- kicad.orig/eeschema/general.h	2010-04-28 04:34:54.000000000 -0300
+++ kicad/eeschema/general.h	2010-04-28 05:42:13.000000000 -0300
@@ -118,6 +118,7 @@
 {
     int NbErrorErc;
     int NbWarningErc;
+    int NbExceptionErc;
 };
 
 extern struct EESchemaVariables g_EESchemaVar;