20060303

1 files changed, 127 insertions, 0 deletions

diff --git a/os/pc/cga.c b/os/pc/cga.c
new file mode 100644
index 00000000..6365d44c
--- /dev/null
+++ b/os/pc/cga.c
@@ -0,0 +1,127 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+
+enum {
+	Black,
+	Blue,
+	Green,
+	Cyan,
+	Red,
+	Magenta,
+	Brown,
+	Grey,
+
+	Bright = 0x08,
+	Blinking = 0x80,
+
+	Yellow = Bright|Brown,
+	White = Bright|Grey,
+};
+	
+enum {
+	Width		= 80*2,
+	Height		= 25,
+
+	Attr		= (Black<<4)|Grey,	/* high nibble background
+						 * low foreground
+						 */
+};
+
+#define CGASCREENBASE	((uchar*)KADDR(0xB8000))
+
+static int cgapos;
+static Lock cgascreenlock;
+
+static uchar
+cgaregr(int index)
+{
+	outb(0x3D4, index);
+	return inb(0x3D4+1) & 0xFF;
+}
+
+static void
+cgaregw(int index, int data)
+{
+	outb(0x3D4, index);
+	outb(0x3D4+1, data);
+}
+
+static void
+movecursor(void)
+{
+	cgaregw(0x0E, (cgapos/2>>8) & 0xFF);
+	cgaregw(0x0F, cgapos/2 & 0xFF);
+	CGASCREENBASE[cgapos+1] = Attr;
+}
+
+static void
+cgascreenputc(int c)
+{
+	int i;
+	uchar *p;
+
+	if(c == '\n'){
+		cgapos = cgapos/Width;
+		cgapos = (cgapos+1)*Width;
+	}
+	else if(c == '\t'){
+		i = 8 - ((cgapos/2)&7);
+		while(i-->0)
+			cgascreenputc(' ');
+	}
+	else if(c == '\b'){
+		if(cgapos >= 2)
+			cgapos -= 2;
+		cgascreenputc(' ');
+		cgapos -= 2;
+	}
+	else{
+		CGASCREENBASE[cgapos++] = c;
+		CGASCREENBASE[cgapos++] = Attr;
+	}
+	if(cgapos >= Width*Height){
+		memmove(CGASCREENBASE, &CGASCREENBASE[Width], Width*(Height-1));
+		p = &CGASCREENBASE[Width*(Height-1)];
+		for(i=0; i<Width/2; i++){
+			*p++ = ' ';
+			*p++ = Attr;
+		}
+		cgapos = Width*(Height-1);
+	}
+	movecursor();
+}
+
+static void
+cgascreenputs(char* s, int n)
+{
+	if(!islo()){
+		/*
+		 * Don't deadlock trying to
+		 * print in an interrupt.
+		 */
+		if(!canlock(&cgascreenlock))
+			return;
+	}
+	else
+		lock(&cgascreenlock);
+
+	while(n-- > 0)
+		cgascreenputc(*s++);
+
+	unlock(&cgascreenlock);
+}
+
+void
+screeninit(void)
+{
+
+	cgapos = cgaregr(0x0E)<<8;
+	cgapos |= cgaregr(0x0F);
+	cgapos *= 2;
+
+	screenputs = cgascreenputs;
+}