1 files changed, 127 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/i386/include/realmode.h b/contrib/syslinux-4.02/gpxe/src/arch/i386/include/realmode.h
new file mode 100644
index 0000000..a0a830b
--- /dev/null
+++ b/contrib/syslinux-4.02/gpxe/src/arch/i386/include/realmode.h
@@ -0,0 +1,127 @@
+#ifndef REALMODE_H
+#define REALMODE_H
+
+#include <stdint.h>
+#include <registers.h>
+#include <gpxe/uaccess.h>
+
+/*
+ * Data structures and type definitions
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/*
+ * Declaration of variables in .data16
+ *
+ * To place a variable in the .data16 segment, declare it using the
+ * pattern:
+ *
+ *   int __data16 ( foo );
+ *   #define foo __use_data16 ( foo );
+ *
+ *   extern uint32_t __data16 ( bar );
+ *   #define bar __use_data16 ( bar );
+ *
+ *   static long __data16 ( baz ) = 0xff000000UL;
+ *   #define baz __use_data16 ( baz );
+ *
+ * i.e. take a normal declaration, add __data16() around the variable
+ * name, and add a line saying "#define <name> __use_data16 ( <name> )
+ *
+ * You can then access them just like any other variable, for example
+ *
+ *   int x = foo + bar;
+ *
+ * This magic is achieved at a cost of only around 7 extra bytes per
+ * group of accesses to .data16 variables.  When using KEEP_IT_REAL,
+ * there is no extra cost.
+ *
+ * You should place variables in .data16 when they need to be accessed
+ * by real-mode code.  Real-mode assembly (e.g. as created by
+ * REAL_CODE()) can access these variables via the usual data segment.
+ * You can therefore write something like
+ *
+ *   static uint16_t __data16 ( foo );
+ *   #define foo __use_data16 ( foo )
+ *
+ *   int bar ( void ) {
+ *     __asm__ __volatile__ ( REAL_CODE ( "int $0xff\n\t"
+ *                                        "movw %ax, foo" )
+ *                            : : );
+ *     return foo;
+ *   }
+ *
+ * Variables may also be placed in .text16 using __text16 and
+ * __use_text16.  Some variables (e.g. chained interrupt vectors) fit
+ * most naturally in .text16; most should be in .data16.
+ *
+ * If you have only a pointer to a magic symbol within .data16 or
+ * .text16, rather than the symbol itself, you can attempt to extract
+ * the underlying symbol name using __from_data16() or
+ * __from_text16().  This is not for the faint-hearted; check the
+ * assembler output to make sure that it's doing the right thing.
+ */
+
+/**
+ * Copy data to base memory
+ *
+ * @v dest_seg		Destination segment
+ * @v dest_off		Destination offset
+ * @v src		Source
+ * @v len		Length
+ */
+static inline __always_inline void
+copy_to_real ( unsigned int dest_seg, unsigned int dest_off,
+	       void *src, size_t n ) {
+	copy_to_user ( real_to_user ( dest_seg, dest_off ), 0, src, n );
+}
+
+/**
+ * Copy data to base memory
+ *
+ * @v dest		Destination
+ * @v src_seg		Source segment
+ * @v src_off		Source offset
+ * @v len		Length
+ */
+static inline __always_inline void
+copy_from_real ( void *dest, unsigned int src_seg,
+		 unsigned int src_off, size_t n ) {
+	copy_from_user ( dest, real_to_user ( src_seg, src_off ), 0, n );
+}
+
+/**
+ * Write a single variable to base memory
+ *
+ * @v var		Variable to write
+ * @v dest_seg		Destination segment
+ * @v dest_off		Destination offset
+ */
+#define put_real( var, dest_seg, dest_off ) \
+	copy_to_real ( (dest_seg), (dest_off), &(var), sizeof (var) )
+
+/**
+ * Read a single variable from base memory
+ *
+ * @v var		Variable to read
+ * @v src_seg		Source segment
+ * @v src_off		Source offset
+ */
+#define get_real( var, src_seg, src_off ) \
+	copy_from_real ( &(var), (src_seg), (src_off), sizeof (var) )
+
+/*
+ * REAL_CODE ( asm_code_str )
+ *
+ * This can be used in inline assembly to create a fragment of code
+ * that will execute in real mode.  For example: to write a character
+ * to the BIOS console using INT 10, you would do something like:
+ *
+ *     __asm__ __volatile__ ( REAL_CODE ( "int $0x16" )
+ *			      : "=a" ( character ) : "a" ( 0x0000 ) );
+ *
+ */
+
+#endif /* REALMODE_H */