diff src/pragma.c @ 0:57495da01900

Initial checking of LWASM
author lost
date Fri, 03 Oct 2008 02:44:20 +0000
parents
children 34568fab6058
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pragma.c	Fri Oct 03 02:44:20 2008 +0000
@@ -0,0 +1,85 @@
+/*
+ * pragma.c
+ *
+ * stuff associated with lwasm specific strangeness
+ */
+
+#include <ctype.h>
+#include <stdlib.h>
+#include <string.h>
+#include "lwasm.h"
+
+/*
+A pragma is a means of controlling code generation.
+
+The pseudo op "*pragma" which will be treated as a comment by an assembler
+that doesn't recognize it and thus will not cause assembly errors. This is
+the preferred way of flagging a pragma if it will not cause incorrect
+execution of the program.
+
+The pseudo op "pragma" which will cause an error on an assembler that does
+not understand it.
+
+In the case of "*pragma", unrecognized pragmas MUST be silently ignored. In
+the case of "pragma", unrecognized pragmas should raise an error.
+
+LWASM understands the following pragmas:
+
+index0tonone
+noindex0tonone
+
+When set (index0tonone), an expression that evaluates to 0, other than a
+bare constant, in a <offset>,r operand will cause the code for ",r" to be
+emitted rather than "0,r". If not set (noindex0tonone), the "0,r" output
+will be emitted. The default is to perform the optimization.
+
+This particular optimization will save a cycle for a direct operation. For
+an indirect operation, however, it will save several cycles and a program byte
+which may be very useful.
+*/
+
+void pseudo_pragma_real(asmstate_t *as, sourceline_t *cl, char **optr, int error)
+{
+	char pragma[128];
+	int c = 0;
+	
+	while (isspace(**optr))
+		(*optr)++;
+	
+	while (c < 127 && **optr && !isspace(**optr))
+	{
+		pragma[c++] = **optr;
+		(*optr)++;
+	}
+	
+	if (c == 0 || (**optr && !isspace(**optr)))
+	{
+		if (error)
+			errorp1(ERR_PRAGMA);
+		return;
+	}
+	pragma[c] = 0;
+	if (!strcmp(pragma, "noindex0tonone"))
+	{
+		as -> pragmas |= PRAGMA_NOINDEX0TONONE;
+	}
+	else if (!strcmp(pragma, "index0tonone"))
+	{
+		as -> pragmas &= ~PRAGMA_NOINDEX0TONONE;
+	}
+	else
+	{
+		if (error)
+			errorp1(ERR_PRAGMA);
+	}
+}
+
+void pseudo_pragma(asmstate_t *as, sourceline_t *cl, char **optr)
+{
+	pseudo_pragma_real(as, cl, optr, 1);
+}
+
+void pseudo_starpragma(asmstate_t *as, sourceline_t *cl, char **optr)
+{
+	pseudo_pragma_real(as, cl, optr, 0);
+}