Orion

diff --git a/screen.c b/screen.c
new file mode 100644
index 0000000..3a722cc
--- /dev/null
+++ b/screen.c
@@ -0,0 +1,356 @@
+/*
+ * This file controls the kernel screen.  It has several routines which can
+ * output text to the debug port and the the VGA Text Monitor.  Most of these
+ * functions are for logging - except the Kernel Panic routine.  Hopefully it's
+ * never called.  It should probably also halt execution on all CPUs, not just
+ * the local one.  This would need IPIs to be sent, which can be implemented
+ * later.
+ */
+
+#include <stdarg.h>
+#include "mem/mem.h"
+#include "mem/vm.h"
+#include "task/task.h"
+#include "io.h"
+#include "spinlock.h"
+
+#define IS_DIGIT(c) ((c) >= '0' && (c) <= '9')
+
+#define ZEROPAD	1  /* Pad with zero */
+#define SIGN    2  /* Insigned/signed long */
+#define PLUS    4  /* Show plus */
+#define SPACE   8  /* Space if plus */
+#define LEFT    16 /* Left justified */
+#define SPECIAL 32 /* 0x */
+#define SMALL   64 /* Use 'abcdef' instead of 'ABCDEF' */
+
+#define DO_DIV(n,base) ({                                                     \
+	int __res;                                                            \
+	__asm__("divl %4":"=a" (n),"=d" (__res):"0" (n),"1" (0),"r" (base));  \
+	__res;                                                                \
+})
+
+Spinlock screenLock;
+
+/* Do not convert */
+static int
+skip_atoi(const char **s)
+{
+	int i = 0;
+
+	while (IS_DIGIT(**s))
+		i = i*10 + *((*s)++) - '0';
+
+	return i;
+}
+
+/* Convert a number to ASCII */
+static char *
+number(char *str, int num, int base, int size, int precision, int type)
+{
+	char c, sign, tmp[36];
+	const char *digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+	int i;
+
+	if (type & SMALL)
+		digits = "0123456789abcdefghijklmnopqrstuvwxyz";
+	if (type & LEFT)
+		type &= ~ZEROPAD;
+	if (base < 2 || base > 36)
+		return 0;
+	c = (type & ZEROPAD) ? '0' : ' ' ;
+	if (type & SIGN && num < 0) {
+		sign = '-';
+		num = -num;
+	} else {
+		sign = (type & PLUS) ? '+' : ((type & SPACE) ? ' ' : 0);
+	}
+	if (sign)
+		size--;
+	if (type & SPECIAL)
+		if (base == 16)
+			size -= 2;
+		else if (base == 8)
+			size--;
+	i = 0;
+	if (num == 0)
+		tmp[i++] = '0';
+	else while (num != 0)
+		tmp[i++] = digits[DO_DIV(num,base)];
+	if (i > precision)
+		precision = i;
+	size -= precision;
+	if (!(type & (ZEROPAD + LEFT)))
+		while (size-- > 0)
+			*str++ = ' ';
+	if (sign)
+		*str++ = sign;
+	if (type & SPECIAL)
+		if (base == 8) {
+			*str++ = '0';
+		} else if (base == 16) {
+			*str++ = '0';
+			*str++ = digits[33];
+		}
+	if (!(type & LEFT))
+		while (size-- > 0)
+			*str++ = c;
+	while (i < precision--)
+		*str++ = '0';
+	while (i-- > 0)
+		*str++ = tmp[i];
+	while (size-- > 0)
+		*str++ = ' ';
+	return str;
+}
+
+/* Print formatted to a buffer */
+static int
+vsprintf(char *buf, const char *fmt, va_list args)
+{
+	int len, i;
+	char *str, *s, *p;
+	int *ip, flags;
+	int field_width, precision, qualifier;
+
+	for (str = buf; *fmt; fmt++) {
+		if (*fmt != '%') {
+			*str++ = *fmt;
+			continue;
+		}
+
+		/* Process flags */
+		flags = 0;
+repeat:
+		fmt++;
+		switch (*fmt) {
+		case '-':
+			flags |= LEFT;
+			goto repeat;
+		case '+':
+			flags |= PLUS;
+			goto repeat;
+		case ' ':
+			flags |= SPACE;
+			goto repeat;
+		case '#':
+			flags |= SPECIAL;
+			goto repeat;
+		case '0':
+			flags |= ZEROPAD;
+			goto repeat;
+		}
+
+		/* Get field width */
+		field_width = -1;
+		if (IS_DIGIT(*fmt)) {
+			field_width = skip_atoi(&fmt);
+		} else if (*fmt == '*') {
+			field_width = va_arg(args, int);
+			if (field_width < 0) {
+				field_width = -field_width;
+				flags |= LEFT;
+			}
+		}
+
+		/* Get the precision */
+		precision = -1;
+		if (*fmt == '.') {
+			fmt++;
+			if (IS_DIGIT(*fmt)) {
+				precision = skip_atoi(&fmt);
+			} else if (*fmt == '*') {
+				precision = va_arg(args, int);
+			}
+			if (precision < 0)
+				precision = 0;
+		}
+
+		/* Get the conversion qualifier */
+		qualifier = -1;
+		if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') {
+			qualifier = *fmt;
+			fmt++;
+		}
+
+		switch (*fmt) {
+		case 'c':
+			if (!(flags & LEFT))
+				while (--field_width > 0)
+					*str++ = ' ';
+			*str++ = (unsigned char) va_arg(args, int);
+			while (--field_width > 0)
+				*str++ = ' ';
+			break;
+
+		case 's':
+			s = va_arg(args, char *);
+			len = 0;
+			p = s;
+			while (*p++) len++;
+			if (precision < 0)
+				precision = len;
+			else if (len > precision)
+				len = precision;
+
+			if (!(flags & LEFT))
+				while (len < field_width--)
+					*str++ = ' ';
+			for (i = 0; i < len; ++i)
+				*str++ = *s++;
+			while (len < field_width--)
+				*str++ = ' ';
+			break;
+
+		case 'o':
+			str = number(str, va_arg(args, unsigned long), 8,
+				field_width, precision, flags);
+			break;
+
+		case 'p':
+			if (field_width == -1) {
+				field_width = 8;
+				flags |= ZEROPAD;
+			}
+			str = number(str,
+				(unsigned long) va_arg(args, void *), 16,
+				field_width, precision, flags);
+			break;
+
+		case 'x':
+			flags |= SMALL;
+			/* FALLTHROUGH */
+		case 'X':
+			str = number(str, va_arg(args, unsigned long), 16,
+				field_width, precision, flags);
+			break;
+
+		case 'd': /* FALLTHROUGH */
+		case 'i':
+			flags |= SIGN;
+			/* FALLTHROUGH */
+		case 'u':
+			str = number(str, va_arg(args, unsigned long), 10,
+				field_width, precision, flags);
+			break;
+
+		case 'n':
+			ip = va_arg(args, int *);
+			*ip = (str - buf);
+			break;
+
+		default:
+			if (*fmt != '%')
+				*str++ = '%';
+			if (*fmt)
+				*str++ = *fmt;
+			else
+				--fmt;
+			break;
+		}
+	}
+	*str = '\0';
+	return str-buf;
+}
+
+/* Format a string into a buffer */
+int
+sprintf(char *buf, char *fmt, ...)
+{
+	int ret;
+	va_list args;
+	va_start(args, fmt);
+	ret = vsprintf(buf, fmt, args);
+	va_end(args);
+	return ret;
+}
+
+/* Print a character */
+static inline void
+print_char(char c)
+{
+	outb(0xE9, c);
+}
+
+/* Set the output colour */
+static inline void
+set_attribute(char c, char *esc)
+{
+	while (*esc)
+		outb(0xE9, *esc++);
+}
+
+/* Kernel panic */
+void
+panic(char *fmt, ...)
+{
+	char buf[1024], *error = buf;
+
+	/* Print error to serial port */
+	acquire(&screenLock);
+	set_attribute(0x04, "\033[31m");
+	va_list args;
+	va_start(args, fmt);
+	vsprintf(buf, fmt, args);
+	va_end(args);
+	while (*error) print_char(*error++);
+	print_char('\n');
+	release(&screenLock);
+
+	/* Hang */
+	while (1) asm("hlt");
+}
+
+/* Kernel print */
+void
+kprintf(char *fmt, ...)
+{
+	char buf[1024], *error = buf;
+
+	/* Print to debug port */
+	acquire(&screenLock);
+	set_attribute(0x03, "\033[36m");
+	va_list args;
+	va_start(args, fmt);
+	vsprintf(buf, fmt, args);
+	va_end(args);
+	while (*error) print_char(*error++);
+	print_char('\n');
+	release(&screenLock);
+}
+
+/* Debug prefix print */
+static void
+dbgprefix(char *fmt, ...)
+{
+	char buf[1024], *error = buf;
+
+	/* Print to debug port */
+	set_attribute(0x0E, "\033[93;01m");
+	va_list args;
+	va_start(args, fmt);
+	vsprintf(buf, fmt, args);
+	va_end(args);
+	while (*error) print_char(*error++);
+}
+
+/* Debug print */
+void
+dbgprintf(char *msg)
+{
+	size_t len = 1024;
+
+	if (!msg)
+		return;
+
+	if (!verify_access(msg, strnlen(msg, len), PROT_READ))
+		return;
+
+	/* Print to debug port */
+	acquire(&screenLock);
+	dbgprefix("%s(%d:%d): ", current->name, current->tgid, current->tid);
+	set_attribute(0x0F, "\033[0m");
+	while (*msg && len--) print_char(*msg++);
+	print_char('\n');
+	release(&screenLock);
+}