Add debug output and a few elementary stdlib functions.

1 files changed, 151 insertions, 0 deletions

diff --git a/kernel/l0/dbglog.c b/kernel/l0/dbglog.c
new file mode 100644
index 0000000..0285002
--- /dev/null
+++ b/kernel/l0/dbglog.c
@@ -0,0 +1,151 @@
+#include <stdarg.h>
+#include <stdlib.h>
+#include <printf.h>
+#include <dbglog.h>
+#include <config.h>
+#include <sys.h>
+
+// ==================================================================
+
+#ifdef DBGLOG_TO_SCREEN
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+
+static uint8_t vga_color = 7;
+static uint16_t* vga_buffer = 0;
+static uint16_t vga_row = 0, vga_column = 0;
+
+static uint16_t make_vgaentry(char c, uint8_t color) {
+	uint16_t c16 = c;
+	uint16_t color16 = color;
+	return c16 | color16 << 8;
+}
+
+static void vga_putentryat(char c, uint8_t color, size_t x, size_t y) {
+	const size_t index = y * VGA_WIDTH + x;
+	vga_buffer[index] = make_vgaentry(c, color);
+}
+
+static void vga_update_cursor() {
+	uint16_t cursor_location = vga_row * 80 + vga_column;
+	outb(0x3D4, 14);	//Sending high cursor byte
+	outb(0x3D5, cursor_location >> 8);
+	outb(0x3D4, 15);	//Sending high cursor byte
+	outb(0x3D5, cursor_location);
+}
+ 
+static void vga_init() {
+	vga_row = 0;
+	vga_column = 0;
+	vga_buffer = (uint16_t*) (&k_highhalf_addr + 0xB8000);
+
+	for (size_t y = 0; y < VGA_HEIGHT; y++) {
+		for (size_t x = 0; x < VGA_WIDTH; x++) {
+			vga_putentryat(' ', vga_color, x, y);
+		}
+	}
+
+	vga_update_cursor();
+}
+
+static void vga_scroll() {
+	for (size_t i = 0; i < VGA_WIDTH * (VGA_HEIGHT - 1); i++) {
+		vga_buffer[i] = vga_buffer[i + VGA_WIDTH];
+	}
+	for (size_t x = 0; x < VGA_WIDTH; x++) {
+		vga_putentryat(' ', vga_color, x, VGA_HEIGHT - 1);
+	}
+	vga_row--;
+}
+
+static void vga_newline() {
+	vga_column = 0;
+	if (++vga_row == VGA_HEIGHT) {
+		vga_scroll();
+	}
+}
+ 
+static void vga_putc(char c) {
+	if (c == '\n') {
+		vga_newline();
+	} else if (c == '\t') {
+		vga_putc(' ');
+		while (vga_column % 4 != 0) vga_putc(' ');
+	} else {
+		vga_putentryat(c, vga_color, vga_column, vga_row);
+		if (++vga_column == VGA_WIDTH) {
+			vga_newline();
+		}
+	}
+}
+ 
+static void vga_puts(const char* data) {
+	size_t datalen = strlen(data);
+	for (size_t i = 0; i < datalen; i++)
+		vga_putc(data[i]);
+
+	vga_update_cursor();
+}
+
+#endif	// DBGLOG_TO_SCREEN
+
+// ==================================================================
+
+#ifdef DBGLOG_TO_SERIAL
+
+#define SER_PORT 0x3F8		// COM1
+
+static void serial_init() {
+	outb(SER_PORT + 1, 0x00);		// disable interrupts
+	outb(SER_PORT + 3, 0x80);		// set baud rate
+	outb(SER_PORT + 0, 0x03);		// set divisor to 3 (38400 baud)
+	outb(SER_PORT + 1, 0x00);
+	outb(SER_PORT + 3, 0x03);		// 8 bits, no parity, one stop bit
+	outb(SER_PORT + 2, 0xC7);		// enable FIFO, clear them, with 14-byte threshold
+}
+
+static void serial_putc(const char c) {
+	while (!(inb(SER_PORT + 5) & 0x20));
+	outb(SER_PORT, c);
+}
+
+static void serial_puts(const char *c) {
+	while (*c) {
+		serial_putc(*c);
+		c++;
+	}
+}
+
+#endif	// DBGLOG_TO_SERIAL
+
+// ==================================================================
+
+void dbglog_setup() {
+#ifdef DBGLOG_TO_SCREEN
+	vga_init();
+#endif
+#ifdef DBGLOG_TO_SERIAL
+	serial_init();
+#endif
+}
+
+void dbg_print(const char* str) {
+#ifdef DBGLOG_TO_SCREEN
+	vga_puts(str);
+#endif
+#ifdef DBGLOG_TO_SERIAL
+	serial_puts(str);
+#endif
+}
+
+void dbg_printf(const char* fmt, ...) {
+	va_list ap;
+	char buffer[256];
+
+	va_start(ap, fmt);
+	vsnprintf(buffer, 256, fmt, ap);
+	va_end(ap);
+
+	dbg_print(buffer);
+}