20060303

1 files changed, 102 insertions, 0 deletions

diff --git a/os/pc/vgax.c b/os/pc/vgax.c
new file mode 100644
index 00000000..c765508e
--- /dev/null
+++ b/os/pc/vgax.c
@@ -0,0 +1,102 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+
+#define	Image	IMAGE
+#include <draw.h>
+#include <memdraw.h>
+#include <cursor.h>
+#include "screen.h"
+
+static Lock vgaxlock;			/* access to index registers */
+
+int
+vgaxi(long port, uchar index)
+{
+	uchar data;
+
+	ilock(&vgaxlock);
+	switch(port){
+
+	case Seqx:
+	case Crtx:
+	case Grx:
+		outb(port, index);
+		data = inb(port+1);
+		break;
+
+	case Attrx:
+		/*
+		 * Allow processor access to the colour
+		 * palette registers. Writes to Attrx must
+		 * be preceded by a read from Status1 to
+		 * initialise the register to point to the
+		 * index register and not the data register.
+		 * Processor access is allowed by turning
+		 * off bit 0x20.
+		 */
+		inb(Status1);
+		if(index < 0x10){
+			outb(Attrx, index);
+			data = inb(Attrx+1);
+			inb(Status1);
+			outb(Attrx, 0x20|index);
+		}
+		else{
+			outb(Attrx, 0x20|index);
+			data = inb(Attrx+1);
+		}
+		break;
+
+	default:
+		iunlock(&vgaxlock);
+		return -1;
+	}
+	iunlock(&vgaxlock);
+
+	return data & 0xFF;
+}
+
+int
+vgaxo(long port, uchar index, uchar data)
+{
+	ilock(&vgaxlock);
+	switch(port){
+
+	case Seqx:
+	case Crtx:
+	case Grx:
+		/*
+		 * We could use an outport here, but some chips
+		 * (e.g. 86C928) have trouble with that for some
+		 * registers.
+		 */
+		outb(port, index);
+		outb(port+1, data);
+		break;
+
+	case Attrx:
+		inb(Status1);
+		if(index < 0x10){
+			outb(Attrx, index);
+			outb(Attrx, data);
+			inb(Status1);
+			outb(Attrx, 0x20|index);
+		}
+		else{
+			outb(Attrx, 0x20|index);
+			outb(Attrx, data);
+		}
+		break;
+
+	default:
+		iunlock(&vgaxlock);
+		return -1;
+	}
+	iunlock(&vgaxlock);
+
+	return 0;
+}