Add debug output and a few elementary stdlib functions.

3 files changed, 205 insertions, 122 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);
+}
diff --git a/kernel/l0/kmain.c b/kernel/l0/kmain.c
index 9139856..74945e4 100644
--- a/kernel/l0/kmain.c
+++ b/kernel/l0/kmain.c
@@ -1,126 +1,14 @@
-#if !defined(__cplusplus)
-#include <stdbool.h> /* C doesn't have booleans by default. */
-#endif
-#include <stddef.h>
-#include <stdint.h>
+#include <multiboot.h>
+#include <config.h>
+#include <dbglog.h>
+#include <sys.h>
  
-/* Check if the compiler thinks if we are targeting the wrong operating system. */
-#if defined(__linux__)
-#error "You are not using a cross-compiler, you will most certainly run into trouble"
-#endif
- 
-/* This tutorial will only work for the 32-bit ix86 targets. */
-#if !defined(__i386__)
-#error "This tutorial needs to be compiled with a ix86-elf compiler"
-#endif
+void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) {
+	dbglog_setup();
 
-#include "multiboot.h"
- 
-extern void k_highhalf_addr;
+	dbg_printf("Hello, kernel World!\n");
+	dbg_printf("This is %s, version %s.\n", OS_NAME, OS_VERSION);
 
-/* Hardware text mode color constants. */
-enum vga_color
-{
-	COLOR_BLACK = 0,
-	COLOR_BLUE = 1,
-	COLOR_GREEN = 2,
-	COLOR_CYAN = 3,
-	COLOR_RED = 4,
-	COLOR_MAGENTA = 5,
-	COLOR_BROWN = 6,
-	COLOR_LIGHT_GREY = 7,
-	COLOR_DARK_GREY = 8,
-	COLOR_LIGHT_BLUE = 9,
-	COLOR_LIGHT_GREEN = 10,
-	COLOR_LIGHT_CYAN = 11,
-	COLOR_LIGHT_RED = 12,
-	COLOR_LIGHT_MAGENTA = 13,
-	COLOR_LIGHT_BROWN = 14,
-	COLOR_WHITE = 15,
-};
- 
-uint8_t make_color(enum vga_color fg, enum vga_color bg)
-{
-	return fg | bg << 4;
-}
- 
-uint16_t make_vgaentry(char c, uint8_t color)
-{
-	uint16_t c16 = c;
-	uint16_t color16 = color;
-	return c16 | color16 << 8;
-}
- 
-size_t strlen(const char* str)
-{
-	size_t ret = 0;
-	while ( str[ret] != 0 )
-		ret++;
-	return ret;
-}
- 
-static const size_t VGA_WIDTH = 80;
-static const size_t VGA_HEIGHT = 25;
- 
-size_t terminal_row;
-size_t terminal_column;
-uint8_t terminal_color;
-uint16_t* terminal_buffer;
- 
-void terminal_initialize()
-{
-	terminal_row = 0;
-	terminal_column = 0;
-	terminal_color = make_color(COLOR_LIGHT_GREY, COLOR_BLACK);
-	terminal_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++ )
-		{
-			const size_t index = y * VGA_WIDTH + x;
-			terminal_buffer[index] = make_vgaentry(' ', terminal_color);
-		}
-	}
-}
- 
-void terminal_setcolor(uint8_t color)
-{
-	terminal_color = color;
-}
- 
-void terminal_putentryat(char c, uint8_t color, size_t x, size_t y)
-{
-	const size_t index = y * VGA_WIDTH + x;
-	terminal_buffer[index] = make_vgaentry(c, color);
-}
- 
-void terminal_putchar(char c)
-{
-	terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
-	if ( ++terminal_column == VGA_WIDTH )
-	{
-		terminal_column = 0;
-		if ( ++terminal_row == VGA_HEIGHT )
-		{
-			terminal_row = 0;
-		}
-	}
-}
- 
-void terminal_writestring(const char* data)
-{
-	size_t datalen = strlen(data);
-	for ( size_t i = 0; i < datalen; i++ )
-		terminal_putchar(data[i]);
-}
- 
-#if defined(__cplusplus)
-extern "C" /* Use C linkage for kernel_main. */
-#endif
-void kmain(struct multiboot_info_t *mbd, int32_t mb_magic)
-{
-	terminal_initialize();
-	/* Since there is no support for newlines in terminal_putchar yet, \n will
-	   produce some VGA specific character instead. This is normal. */
-	terminal_writestring("Hello, kernel World!\n");
+	PANIC("Reached kmain end! Falling off the edge.");
 }
+
diff --git a/kernel/l0/sys.c b/kernel/l0/sys.c
new file mode 100644
index 0000000..f6a9900
--- /dev/null
+++ b/kernel/l0/sys.c
@@ -0,0 +1,44 @@
+#include <sys.h>
+#include <dbglog.h>
+
+
+// C wrappers for inb/outb/inw/outw
+
+void outb(uint16_t port, uint8_t value) {
+	asm volatile("outb %1, %0" : : "dN"(port), "a"(value));
+}
+
+void outw(uint16_t port, uint16_t value) {
+	asm volatile("outw %1, %0" : : "dN"(port), "a"(value));
+}
+
+uint8_t inb(uint16_t port) {
+	uint8_t ret;
+	asm volatile("inb %1, %0" : "=a"(ret) : "dN"(port));
+	return ret;
+}
+
+uint16_t inw(uint16_t port) {
+	uint16_t ret;
+	asm volatile("inw %1, %0" : "=a"(ret) : "dN"(port));
+	return ret;
+}
+
+// Kernel panic and kernel assert failure
+
+static void panic_do(const char* type, const char *msg, const char* file, int line) {
+	asm volatile("cli;");
+	dbg_printf("/\n| %s:\t%s\n", type, msg);
+	dbg_printf("| File: \t%s:%i\n", file, line);
+	dbg_printf("| System halted -_-'\n");
+	dbg_printf("\\---------------------------------------------------------/");
+	asm volatile("hlt");
+}
+
+void panic(const char* message, const char* file, int line) {
+	panic_do("PANIC", message, file, line);
+}
+
+void panic_assert(const char* assertion, const char* file, int line) {
+	panic_do("ASSERT FAILED", assertion, file, line);
+}