Added a more generic way to push sources that deliver a token stream

independent of the actual input from the file. Change macro handling
to use the new input stack.
Fixed an error in FreeIf: If an unexpected .ENDIF was reached, the
assembler started an endless loop printing error messages.


git-svn-id: svn://svn.cc65.org/cc65/trunk@24 b7a2c559-68d2-44c3-8de9-860c34a00d81

src/ca65/istack.c

@@ -0,0 +1,149 @@
+/*****************************************************************************/
+/*                                                                           */
+/*				   istack.c				     */
+/*                                                                           */
+/*			  Input stack for the scanner			     */
+/*                                                                           */
+/*                                                                           */
+/*                                                                           */
+/* (C) 2000     Ullrich von Bassewitz                                        */
+/*              Wacholderweg 14                                              */
+/*              D-70597 Stuttgart                                            */
+/* EMail:       uz@musoftware.de                                             */
+/*                                                                           */
+/*                                                                           */
+/* This software is provided 'as-is', without any expressed or implied       */
+/* warranty.  In no event will the authors be held liable for any damages    */
+/* arising from the use of this software.                                    */
+/*                                                                           */
+/* Permission is granted to anyone to use this software for any purpose,     */
+/* including commercial applications, and to alter it and redistribute it    */
+/* freely, subject to the following restrictions:                            */
+/*                                                                           */
+/* 1. The origin of this software must not be misrepresented; you must not   */
+/*    claim that you wrote the original software. If you use this software   */
+/*    in a product, an acknowledgment in the product documentation would be  */
+/*    appreciated but is not required.                                       */
+/* 2. Altered source versions must be plainly marked as such, and must not   */
+/*    be misrepresented as being the original software.                      */
+/* 3. This notice may not be removed or altered from any source              */
+/*    distribution.                                                          */
+/*                                                                           */
+/*****************************************************************************/
+
+
+
+#include "error.h"
+#include "mem.h"
+#include "istack.h"
+
+
+
+/*****************************************************************************/
+/*     	       	    		     Data			   	     */
+/*****************************************************************************/
+
+
+
+/* Size of the stack (== maximum nested macro or repeat count) */
+#define ISTACK_MAX  	256
+
+/* Structure holding a stack element */
+typedef struct IElement IElement;
+struct IElement {
+    IElement*  	Next;		/* Next stack element */
+    int	       	(*Func)(void*);	/* Function called for input */
+    void*      	Data;	  	/* User data given as argument */
+    const char* Desc;		/* Description */
+};
+
+/* The stack */
+static IElement* IStack = 0;	/* Input stack pointer */
+static unsigned  ICount	= 0;	/* Number of items on the stack */
+
+
+
+/*****************************************************************************/
+/*     	       	    		     Code	 		   	     */
+/*****************************************************************************/
+
+
+
+void PushInput (int (*Func) (void*), void* Data, const char* Desc)
+/* Push an input function onto the input stack */
+{
+    IElement* E;
+
+    /* Check for a stack overflow */
+    if (ICount > ISTACK_MAX) {
+    	Fatal (FAT_NESTING);
+    }
+
+    /* Create a new stack element */
+    E = Xmalloc (sizeof (*E));
+
+    /* Initialize it */
+    E->Func = Func;
+    E->Data = Data;
+    E->Desc = Desc;
+
+    /* Push it */
+    E->Next = IStack;
+    IStack  = E;
+}
+
+
+
+void PopInput (void)
+/* Pop the current input function from the input stack */
+{
+    IElement* E;
+
+    /* We cannot pop from an empty stack */
+    PRECONDITION (IStack != 0);
+
+    /* Remember the last element */
+    E = IStack;
+
+    /* Pop it */
+    IStack = IStack->Next;
+
+    /* And delete it */
+    Xfree (E);
+}
+
+
+
+int InputFromStack (void)
+/* Try to get input from the input stack. Return true if we had such input,
+ * return false otherwise.
+ */
+{
+    /* Repeatedly call the TOS routine until we have a token or if run out of
+     * routines.
+     */
+    while (IStack) {
+	if (IStack->Func (IStack->Data) != 0) {
+	    /* We have a token */
+	    return 1;
+	}
+    }
+
+    /* Nothing is on the stack */
+    return 0;
+}
+
+
+
+void CheckInputStack (void)
+/* Called from the scanner before closing an input file. Will check for any
+ * stuff on the input stack.
+ */
+{
+    if (IStack) {
+	Error (ERR_OPEN_STMT, IStack->Desc);
+    }
+}
+
+
+