Fixed another printk bug.

LICENSE

@@ -0,0 +1,351 @@
+
+   NOTICE! This version of the GPL is the only version which applies to
+ BRaDOS. Any former or later version does not apply unless explicitly stated
+ elsewhere!
+
+ Also, this license does not apply to software which runs under and/or makes
+ system calls to BRaDOS.
+
+ -L. Bradley LaBoon
+
+ -----------------------------------------------------------------------------
+
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
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+License is intended to guarantee your freedom to share and change free
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+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
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+your programs, too.
+
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+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
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+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

Makefile

@@ -0,0 +1,34 @@
+# Build environment
+PREFIX	?= /usr/local/cross
+ARCH	?= i586-elf
+GNU	?= $(PREFIX)/$(ARCH)/bin/$(ARCH)
+
+# Source files
+SOURCES_ASM	:= arch/$(ARCH)/boot.s
+SOURCES_C	:= arch/$(ARCH)/multiboot.c driver/video/vga.c kernel/brados.c kernel/printk.c lib/string.c
+
+# Object files
+OBJS	:= $(patsubst %.s,%.o,$(SOURCES_ASM))
+OBJS	+= $(patsubst %.c,%.o,$(SOURCES_C))
+
+# Build flags
+CFLAGS = -std=gnu99 -ffreestanding -Iinclude/ -O2 -Wall -Wextra
+LDFLAGS = -ffreestanding -O2 -nostdlib
+
+# Build rules
+all: brados.bin
+.PHONY: all clean
+
+brados.bin: $(OBJS) arch/$(ARCH)/linker.ld
+	$(GNU)-gcc -T arch/$(ARCH)/linker.ld -o $@ $(LDFLAGS) $(OBJS) -lgcc
+
+clean:
+	rm -f $(OBJS) brados.bin
+
+# C
+%.o: %.c Makefile
+	$(GNU)-gcc -c $< -o $@ $(CFLAGS)
+
+# Assembly
+%.o: %.s Makefile
+	$(GNU)-as $< -o $@

README

@@ -1,5 +1,9 @@
 Welcome to BRaDOS!
 
 BRaDOS is my personal OS project which I will be working on as I feel like it.
-The main purpose of the project is for me to learn about OS developement, as
+The main purpose of the project is for me to learn about OS developement.
-it's something I am interested in.
+
+For the most part, this project will do things the way Linux does things, with
+changes as I see fit. While I will make every attempt to ensure that the master
+git branch only contains compilable code, I make no guarantees. Use of this OS
+is entirely at your own risk.

arch/arm-none-eabi/boot.s

@@ -0,0 +1,33 @@
+.section ".text.boot"
+
+.globl Start
+Start:
+	// Setup the stack
+	mov	sp, #0x8000
+	
+	// Clear out bss
+	ldr	r4, =_bss_start
+	ldr	r9, =_bss_end
+	mov	r5, #0
+	mov	r6, #0
+	mov	r7, #0
+	mov	r8, #0
+	b	2f
+
+1:
+	// Store multiple at r4
+	stmia	r4!, {r5-r8}
+
+2:
+	// If we are still below bss_end, loop
+	cmp	r4, r9
+	blo	1b
+	
+	// Call brados_main
+	ldr	r3, =brados_main
+	blx	r3
+
+halt:
+	// Halt
+	wfe
+	b	halt

arch/arm-none-eabi/linker.ld

@@ -0,0 +1,42 @@
+ENTRY(Start)
+
+SECTIONS
+{
+	/* Starts at LOADER_ADDR */
+	. = 0x8000;
+	_start = .;
+	_text_start = .;
+	.text :
+	{
+		KEEP(*(.text.boot))
+		*(.text)
+	}
+	. = ALIGN(4096);
+	_text_end = .;
+	
+	_rodata_start = .;
+	.rodata :
+	{
+		*(.rodata)
+	}
+	. = ALIGN(4096);
+	_rodata_end = .;
+	
+	_data_start = .;
+	.data :
+	{
+		*(.data)
+	}
+	. = ALIGN(4096);
+	_data_end = .;
+	
+	_bss_start = .;
+	.bss :
+	{
+		bss = .;
+		*(.bss)
+	}
+	. = ALIGN(4096);
+	_bss_end = .;
+	_end = .;
+}

arch/arm-none-eabi/multiboot.c

@@ -0,0 +1,13 @@
+#include <stdint.h>
+
+#include <multiboot.h>
+
+uint32_t multiboot_getAddress()
+{
+	return 0;
+}
+
+uint32_t multiboot_getMagic()
+{
+	return 0;
+}

arch/i586-elf/boot.s

@@ -27,6 +27,9 @@ _start:
 	# Setup the stack
 	movl $stack_top, %esp
 	
+	# Push the multiboot information onto the stack
+	push %ebx
+	push %eax
 	# Call the main kernel function
 	call brados_main
 	

arch/i586-elf/multiboot.c

@@ -0,0 +1,23 @@
+#include <stdint.h>
+
+#include <multiboot.h>
+
+uint32_t multiboot_getAddress()
+{
+	uint32_t address = 0;
+	__asm__(
+		"movl %%ebx, %0;"
+		:"=r"(address)
+	);
+	return address;
+}
+
+uint32_t multiboot_getMagic()
+{
+	uint32_t magic = 0;
+	__asm__(
+		"movl %%eax, %0;"
+		:"=r"(magic)
+	);
+	return magic;
+}

driver/video/vga.c

@@ -0,0 +1,111 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#include <brados/string.h>
+#include <video/vga.h>
+
+// Create a VGA color
+uint8_t make_color(enum vga_color fg, enum vga_color bg)
+{
+	return fg | bg << 4;
+}
+
+// Create a VGA character
+uint16_t make_vgaEntry(char c, uint8_t color)
+{
+	uint16_t c16 = c;
+	uint16_t color16 = color;
+	return c16 | color16 << 8;
+}
+
+// Initialize a VGA term
+void term_init(struct vgastate *state)
+{
+	state->term_row = state->term_col = 0;
+	state->term_color = make_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
+	state->term_buf = (uint16_t *) VGA_BUF;
+	
+	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;
+			state->term_buf[index] = make_vgaEntry(' ', state->term_color);
+		}
+	}
+}
+
+// Write a character to a VGA term
+void term_putChar(struct vgastate *state, char c)
+{
+	if (c == '\n')
+		state->term_col = VGA_WIDTH - 1;
+	else
+		term_putEntryAt(state, c, state->term_color, state->term_col, state->term_row);
+	
+	if (++state->term_col == VGA_WIDTH) {
+		state->term_col = 0;
+		if (++state->term_row == VGA_HEIGHT) {
+			state->term_row--;
+			term_scroll(state);
+		}
+	}
+}
+
+// Place a character in a VGA term's buffer
+void term_putEntryAt(struct vgastate *state, char c, uint8_t color, size_t x, size_t y)
+{
+	const size_t index = y * VGA_WIDTH + x;
+	state->term_buf[index] = make_vgaEntry(c, color);
+}
+
+// Scroll the term down 1 line
+void term_scroll(struct vgastate *state)
+{
+	// Move each row up
+	for (size_t y = 1; y < VGA_HEIGHT; y++) {
+		for (size_t x = 0; x < VGA_WIDTH; x++) {
+			const size_t index = y * VGA_WIDTH + x;
+			const size_t indexBelow = (y - 1) * VGA_WIDTH + x;
+			state->term_buf[indexBelow] = state->term_buf[index];
+		}
+	}
+	
+	// Clear the last line
+	for (size_t x = 0; x < VGA_WIDTH; x++) {
+		const size_t index = (VGA_HEIGHT - 1) * VGA_WIDTH + x;
+		state->term_buf[index] = ' ';
+	}
+}
+
+// Set VGA term color
+void term_setColor(struct vgastate *state, uint8_t color)
+{
+	state->term_color = color;
+}
+
+// Test various VGA functionality
+void term_test(struct vgastate *term)
+{
+	// Test line wrapping
+	term_writeStr(term, "Welcome to the desert of the real. I thought what I'd do was I'd pretend I was one of those deaf mutes.\n\n");
+	
+	// Test colors
+	term_setColor(term, make_color(VGA_COLOR_BLACK, VGA_COLOR_WHITE));
+	term_writeStr(term, "This text should be inverse.\n");
+	term_setColor(term, make_color(VGA_COLOR_LIGHT_BLUE, VGA_COLOR_GREEN));
+	term_writeStr(term, "This text should be colorful.\n\n");
+	
+	// Test scrolling
+	term_setColor(term, make_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
+	for (size_t i = 0; i < 20; i++) {
+		term_writeStr(term, "Printing some lines.\n");
+		for (volatile size_t j = 0; j < 100000000; j++);
+	}
+}
+
+// Write a string to a VGA term
+void term_writeStr(struct vgastate *state, const char *data)
+{
+	size_t dataLen = strlen(data);
+	for (size_t i = 0; i < dataLen; i++)
+		term_putChar(state, data[i]);
+}

include/brados/printk.h

@@ -0,0 +1,8 @@
+#ifndef __brados_printk_h__
+#define __brados_printk_h__
+
+#include <video/vga.h>
+
+int printk(struct vgastate *term, const char *fmt, ...);
+
+#endif

include/brados/string.h

@@ -0,0 +1,8 @@
+#ifndef __brados_string_h__
+#define __brados_string_h__
+
+#include <stddef.h>
+
+size_t strlen(const char *str);
+
+#endif

include/multiboot.h

@@ -0,0 +1,79 @@
+#ifndef __brados_multiboot_h__
+#define __brados_multiboot_h__
+
+#include <stdint.h>
+
+// For more information on this structure, see:
+// http://www.gnu.org/software/grub/manual/multiboot/multiboot.html
+struct multiboot_header {
+	// Indicates the presence and validity of other fields
+	uint32_t flags;
+	
+	// Present if bit 0 in 'flags' is set
+	uint32_t mem_lower;
+	uint32_t mem_upper;
+	
+	// Present if bit 1 in 'flags' is set
+	uint32_t boot_device;
+	
+	// Present if bit 2 in 'flags' is set
+	uint32_t cmdline;
+	
+	// Present if bit 3 in 'flags' is set
+	uint32_t mods_count;
+	uint32_t mods_addr;
+	
+	// Present if bits 4 or 5 are present in 'flags'
+	// NOTE: Bits 4 and 5 are mutually exclusive. Bit 4 indicates fields
+	// related to a.out kernel images, while bit 5 indicated fields related
+	// to ELF kernel images. Since BRaDOS is an ELF kernel, the bit 5 field
+	// names will be used.
+	uint32_t shdr_num;	// "tabsize" for an a.out kernel
+	uint32_t shdr_size;	// "strsize" for an a.out kernel
+	uint32_t shdr_addr;	// "addr" for an a.out kernel
+	uint32_t shdr_shndx;	// "reserved" for an a.out kernel
+	
+	// Present if bit 6 in 'flags' is set
+	uint32_t mmap_length;
+	uint32_t mmap_addr;
+	
+	// Present if bit 7 in 'flags' is set
+	uint32_t drives_length;
+	uint32_t drives_addr;
+	
+	// Present if bit 8 in 'flags' is set
+	uint32_t config_table;
+	
+	// Present if bit 9 in 'flags' is set
+	uint32_t boot_loader_name;
+	
+	// Present if bit 10 in 'flags' is set
+	uint32_t apm_table;
+	
+	// Present if bit 11 in 'flags' is set
+	uint32_t vbe_control_info;
+	uint32_t vbe_mode_info;
+	uint16_t vbe_mode;
+	uint16_t vbe_interface_seg;
+	uint16_t vbe_interface_off;
+	uint16_t vbe_interface_len;
+};
+
+struct multiboot_mmap {
+	uint32_t size;
+	uint64_t base_addr;
+	uint64_t length;
+	uint32_t type;
+};
+
+struct multiboot_mod {
+	uint32_t mod_start;
+	uint32_t mod_end;
+	uint32_t string;
+	uint32_t reserved;
+};
+
+uint32_t multiboot_getAddress();
+uint32_t multiboot_getMagic();
+
+#endif

include/video/vga.h

@@ -0,0 +1,50 @@
+#ifndef __brados_video_vga_h__
+#define __brados_video_vga_h__
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define VGA_BUF 0xB8000
+
+#define VGA_WIDTH	80
+#define VGA_HEIGHT	24
+
+// VGA State
+struct vgastate {
+	size_t term_row, term_col;
+	uint8_t term_color;
+	uint16_t *term_buf;
+};
+
+// Color constants
+enum vga_color
+{
+	VGA_COLOR_BLACK = 0,
+	VGA_COLOR_BLUE = 1,
+	VGA_COLOR_GREEN = 2,
+	VGA_COLOR_CYAN = 3,
+	VGA_COLOR_RED = 4,
+	VGA_COLOR_MAGENTA = 5,
+	VGA_COLOR_BROWN = 6,
+	VGA_COLOR_LIGHT_GREY = 7,
+	VGA_COLOR_DARK_GREY = 8,
+	VGA_COLOR_LIGHT_BLUE = 9,
+	VGA_COLOR_LIGHT_GREEN = 10,
+	VGA_COLOR_LIGHT_CYAN = 11,
+	VGA_COLOR_LIGHT_RED = 12,
+	VGA_COLOR_LIGHT_MAGENTA = 13,
+	VGA_COLOR_LIGHT_BROWN = 14,
+	VGA_COLOR_WHITE = 15
+};
+
+uint8_t make_color(enum vga_color fg, enum vga_color bg);
+uint16_t make_vgaEntry(char c, uint8_t color);
+void term_init(struct vgastate *state);
+void term_putChar(struct vgastate *state, char c);
+void term_putEntryAt(struct vgastate *state, char c, uint8_t color, size_t x, size_t y);
+void term_scroll(struct vgastate *state);
+void term_setColor(struct vgastate *state, uint8_t color);
+void term_test(struct vgastate *term);
+void term_writeStr(struct vgastate *state, const char *data);
+
+#endif

kernel/brados.c

@@ -1,156 +1,59 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include <brados/printk.h>
+#include <brados/string.h>
+#include <video/vga.h>
+#include <multiboot.h>
+
 // Make sure we are using the right compiler
 #if defined(__linux__)
 #error "You are using the wrong compiler."
 #endif
 
-// 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
-};
-
-// Create a VGA color
-uint8_t make_color(enum vga_color fg, enum vga_color bg)
-{
-	return fg | bg << 4;
-}
-
-// Create a VGA character
-uint16_t make_vgaEntry(char c, uint8_t color)
-{
-	uint16_t c16 = c;
-	uint16_t color16 = color;
-	return c16 | color16 << 8;
-}
-
-// Calculate the length of a string
-size_t strlen(const char *str)
-{
-	size_t len = 0;
-	while (str[len] != 0)
-		len++;
-	return len;
-}
-
-static const size_t VGA_WIDTH = 80;
-static const size_t VGA_HEIGHT = 24;
-
-size_t term_row, term_col;
-uint8_t term_color;
-uint16_t *term_buf;
-
-// Initialize the terminal
-void term_init()
-{
-	term_row = term_col = 0;
-	term_color = make_color(COLOR_LIGHT_GREY, COLOR_BLACK);
-	term_buf = (uint16_t *) 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;
-			term_buf[index] = make_vgaEntry(' ', term_color);
-		}
-	}
-}
-
-// Set the terminal color
-void term_setColor(uint8_t color)
-{
-	term_color = color;
-}
-
-// Place a character in the buffer
-void term_putEntryAt(char c, uint8_t color, size_t x, size_t y)
-{
-	const size_t index = y * VGA_WIDTH + x;
-	term_buf[index] = make_vgaEntry(c, color);
-}
-
-// Scroll down 1 line
-void term_scroll()
-{
-	for (size_t y = 1; y < VGA_HEIGHT; y++) {
-		for (size_t x = 0; x < VGA_WIDTH; x++) {
-			const size_t index = y * VGA_WIDTH + x;
-			const size_t indexBelow = (y - 1) * VGA_WIDTH + x;
-			term_buf[indexBelow] = term_buf[index];
-		}
-	}
-	
-	for (size_t x = 0; x < VGA_WIDTH; x++) {
-		const size_t index = (VGA_HEIGHT - 1) * VGA_WIDTH + x;
-		term_buf[index] = ' ';
-	}
-}
-
-// Write a character to the terminal
-void term_putChar(char c)
-{
-	if (c == '\n')
-		term_col = VGA_WIDTH - 1;
-	else
-		term_putEntryAt(c, term_color, term_col, term_row);
-	
-	if (++term_col == VGA_WIDTH) {
-		term_col = 0;
-		if (++term_row == VGA_HEIGHT) {
-			term_row--;
-			term_scroll();
-		}
-	}
-}
-
-// Write a string to the terminal
-void term_writeStr(const char *data)
-{
-	size_t dataLen = strlen(data);
-	for (size_t i = 0; i < dataLen; i++)
-		term_putChar(data[i]);
-}
-
 // Main kernel function
-void brados_main()
+void brados_main(uint32_t multiMagic, uint32_t multiAddr)
 {
-	term_init();
+	// Initialize VGA terminal
+	struct vgastate term;
+	term_init(&term);
 	
-	// Test printing and newlines
+	// Welcome message
-	term_writeStr("Welcome to BRaDOS!\n");
+	printk(&term, "Welcome to BRaDOS!\n");
-	term_writeStr("written by L. Bradley LaBoon\n\n");
+	printk(&term, "written by L. Bradley LaBoon\n\n");
 	
-	// Test line wrapping
+	// Get multiboot info
-	term_writeStr("The Laughing Man always says: 'I thought what I'd do was I'd pretend I was one of those deaf mutes.'\n\n");
+	if (multiMagic != 0x2BADB002) {
+		printk(&term, "Error! Multiboot header not present. Quitting.\n");
+		return;
+	}
+	struct multiboot_header *multiHead = (struct multiboot_header *) multiAddr;
+	if ((multiHead->flags >> 6) % 2 != 1) {
+		printk(&term, "Error! Memory map not available from bootloader. Quitting.\n");
+		return;
+	}
+	struct multiboot_mmap *memmap = (struct multiboot_mmap *) multiHead->mmap_addr;
 	
-	// Test colors
+	// Print memory map
-	term_setColor(make_color(COLOR_BLACK, COLOR_WHITE));
+	printk(&term, "Memory map:\n");
-	term_writeStr("This text should be inverse.\n");
+	int numEntries = multiHead->mmap_length / sizeof(struct multiboot_mmap);
-	term_setColor(make_color(COLOR_LIGHT_BLUE, COLOR_GREEN));
+	uint64_t lastAddr = 0;
-	term_writeStr("This text should be colorful.\n\n");
+	for (int i = 0; i < numEntries; i++) {
+		if (memmap[i].base_addr != lastAddr) {
+			printk(&term, "%#llx - %#llx: Unknown\n", lastAddr, memmap[i].base_addr - 1);
+			lastAddr = memmap[i].base_addr;
+		}
 		
-	// Test scrolling
+		printk(&term, "%#llx - %#llx: ", memmap[i].base_addr, memmap[i].base_addr + memmap[i].length - 1);
-	term_setColor(make_color(COLOR_LIGHT_GREY, COLOR_BLACK));
+		if (memmap[i].type == 1)
-	for (size_t i = 0; i < 20; i++) {
+			printk(&term, "Available\n");
-		term_writeStr("Printing some lines.\n");
+		else
-		for (size_t j = 0; j < 100000000; j++);
+			printk(&term, "Reserved\n");
+		
+		lastAddr = memmap[i].base_addr + memmap[i].length;
 	}
 	
-	term_writeStr("Done.");
+	
+	// Done
+	printk(&term, "\nDone.");
 }

kernel/printk.c

@@ -0,0 +1,596 @@
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <brados/printk.h>
+#include <brados/string.h>
+#include <video/vga.h>
+
+const char *BASE16 = "0123456789ABCDEF";
+const char *BASE16L = "0123456789abcdef";
+
+// Print an unsigned number as a string; return the number of characters printed
+static int printNum(struct vgastate *term, uintmax_t num, unsigned int base, const char *digits)
+{
+	if (base > strlen(digits))
+		return 0;
+	
+	int numPrinted = 0;
+	int digit = num % base;
+	if (num >= base)
+		numPrinted += printNum(term, num / base, base, digits);
+	term_putChar(term, digits[digit]);
+	numPrinted++;
+	return numPrinted;
+}
+
+// Determines the printed length of a number
+static unsigned int numLen(uintmax_t num, unsigned int base)
+{
+	unsigned int len = 1;
+	while (num >= base) {
+		len++;
+		num /= base;
+	}
+	
+	return len;
+}
+
+// Print a formatted string to the given terminal
+int printk(struct vgastate *term, const char *fmt, ...)
+{
+	int numPrinted = 0;
+	va_list args;
+	va_start(args, fmt);
+	
+	// The bits of 'mode' explained:
+	// 0: Whether we are printing characters normally or parsing the format
+	// 1: Whether we are still parsing flags
+	// 2: Whether we are looking at width or precision (have we seen a .)
+	// 3: + flag
+	// 4: space flag
+	// 5: - flag
+	// 6: # flag
+	// 7: 0 flag
+	uint8_t mode = 0;
+	int length = 0;
+	unsigned int width = 0, precision = 0;
+	
+	for (size_t i = 0; i < strlen(fmt); i++) {
+		if (mode % 2 == 0) {
+			// Begin parsing format if we reach a '%'
+			if (fmt[i] == '%') {
+				mode |= 0x01;
+			// Or just print the character if we're not parsing
+			} else {
+				term_putChar(term, fmt[i]);
+				numPrinted++;
+			}
+			
+			continue;
+		}
+		
+		switch (fmt[i]) {
+		case '%':
+			// Print a percent sign
+			term_putChar(term, '%');
+			numPrinted++;
+			mode = 0;
+			break;
+		case '+':
+			// Set the plus flag
+			if ((mode >> 1) % 2 == 0)
+				mode |= 0x08;
+			
+			break;
+		case ' ':
+			// Set the space flag
+			if ((mode >> 1) % 2 == 0)
+				mode |= 0x10;
+			
+			break;
+		case '-':
+			// Set the left-align flag
+			if ((mode >> 1) % 2 == 0)
+				mode |= 0x20;
+			
+			break;
+		case '#':
+			// Set the alternate flag
+			if ((mode >> 1) % 2 == 0)
+				mode |= 0x40;
+			
+			break;
+		case '0':
+			// Set the zero-pad flag
+			if ((mode >> 1) % 2 == 0)
+				mode |= 0x80;
+			// Next digit in width specifier
+			else if ((mode >> 2) % 2 == 0)
+				width *= 10;
+			// Next digit in precision specifier
+			else
+				precision *= 10;
+			
+			break;
+		case '1':
+		case '2':
+		case '3':
+		case '4':
+		case '5':
+		case '6':
+		case '7':
+		case '8':
+		case '9':
+			// Next digit in width specifier
+			if ((mode >> 2) % 2 == 0) {
+				mode |= 0x02;
+				width *= 10;
+				width += (fmt[i] - 48); // 0 = ascii 48
+			// Next digit in precision specifier
+			} else {
+				precision *= 10;
+				precision += (fmt[i] - 48);
+			}
+			
+			break;
+		case '.':
+			// Delimit width and precision
+			if ((mode >> 2) % 2 == 0)
+				mode |= 0x06;
+			
+			break;
+		case 'h':
+			// Denotes a short or char argument
+			mode |= 0x06;
+			length--;
+			break;
+		case 'l':
+			// Denotes a long or long long argument
+			mode |= 0x06;
+			length++;
+			break;
+		case 'z':
+			// Denotes a size_t argument
+			mode |= 0x06;
+			length = 3;
+			break;
+		case 'j':
+			// Denotes a intmax_t argument
+			mode |= 0x06;
+			length = 4;
+			break;
+		case 't':
+			// Denotes a ptrdiff_t argument
+			mode |= 0x06;
+			length = 5;
+			break;
+		// Print a signed integer
+		case 'd':
+		case 'i': {
+			intmax_t num;
+			uintmax_t unum;
+			
+			// Pull the argument from the list
+			switch (length) {
+				case 1:
+					num = va_arg(args, long);
+					break;
+				case 2:
+					num = va_arg(args, long long);
+					break;
+				case 3:
+					num = va_arg(args, size_t);
+					break;
+				case 4:
+					num = va_arg(args, intmax_t);
+					break;
+				case 5:
+					num = va_arg(args, ptrdiff_t);
+					break;
+				default:
+					num = va_arg(args, int);
+					break;
+			}
+			
+			// Get unsigned version
+			if (num < 0)
+				unum = num * -1;
+			else
+				unum = num;
+			
+			// Get the length of the printed number
+			unsigned int len = numLen(unum, 10);
+			
+			// Get the length of the printed number with formatting
+			unsigned int flen = len;
+			if (precision > len)
+				flen += (precision - len);
+			if (num < 0)
+				flen++;
+			if (num >= 0 && (mode >> 3) + (mode >> 4) > 0)
+				flen++;
+			
+			// If specified, print preceding space padding
+			if ((mode >> 5) % 2 == 0) {
+				if (precision > 0 || (mode >> 7) % 2 == 0) {
+					for (int j = width - flen; j > 0; j--) {
+						term_putChar(term, ' ');
+						numPrinted++;
+					}
+				}
+			}
+			
+			// If specified print the sign
+			if (num < 0) {
+				term_putChar(term, '-');
+				numPrinted++;
+			} else if ((mode >> 3) % 2 == 1) {
+				term_putChar(term, '+');
+				numPrinted++;
+			} else if ((mode >> 4) % 2 == 1) {
+				term_putChar(term, ' ');
+				numPrinted++;
+			}
+			
+			// If specified, print the precision 0s
+			if (precision > 0) {
+				for (int j = precision - len; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			} else if ((mode >> 7) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			}
+			
+			// Print the number
+			numPrinted += printNum(term, unum, 10, BASE16);
+			
+			// If specified, print succeeding spaces
+			if ((mode >> 5) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, ' ');
+					numPrinted++;
+				}
+			}
+			
+			mode = 0;
+			break;
+		// Print an unsigned integer
+		} case 'u': {
+			uintmax_t num;
+			
+			// Pull the argument from the list
+			switch (length) {
+				case 1:
+					num = va_arg(args, unsigned long);
+					break;
+				case 2:
+					num = va_arg(args, unsigned long long);
+					break;
+				case 3:
+					num = va_arg(args, size_t);
+					break;
+				case 4:
+					num = va_arg(args, intmax_t);
+					break;
+				case 5:
+					num = va_arg(args, ptrdiff_t);
+					break;
+				default:
+					num = va_arg(args, unsigned int);
+					break;
+			}
+			
+			// Get the length of the printed number
+			unsigned int len = numLen(num, 10);
+			
+			// Get the length of the printed number with formatting
+			unsigned int flen = len;
+			if (precision > len)
+				flen += (precision - len);
+			if ((mode >> 3) % 2 == 1 || (mode >> 4) % 2 == 1)
+				flen++;
+			
+			// If specified, print preceding space padding
+			if ((mode >> 5) % 2 == 0) {
+				if (precision > 0 || (mode >> 7) % 2 == 0) {
+					for (int j = width - flen; j > 0; j--) {
+						term_putChar(term, ' ');
+						numPrinted++;
+					}
+				}
+			}
+			
+			// If specified print the sign
+			if ((mode >> 3) % 2 == 1) {
+				term_putChar(term, '+');
+				numPrinted++;
+			} else if ((mode >> 4) % 2 == 1) {
+				term_putChar(term, ' ');
+				numPrinted++;
+			}
+			
+			// If specified, print the precision 0s
+			if (precision > 0) {
+				for (int j = precision - len; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			} else if ((mode >> 7) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			}
+			
+			// Print the number
+			numPrinted += printNum(term, num, 10, BASE16);
+			
+			// If specified, print succeeding spaces
+			if ((mode >> 5) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, ' ');
+					numPrinted++;
+				}
+			}
+			
+			mode = 0;
+			break;
+		// Print an unsigned integer in hexadecimal
+		} case 'x':
+		case 'X': {
+			uintmax_t num;
+			
+			// Pull the argument from the list
+			switch (length) {
+				case 1:
+					num = va_arg(args, unsigned long);
+					break;
+				case 2:
+					num = va_arg(args, unsigned long long);
+					break;
+				case 3:
+					num = va_arg(args, size_t);
+					break;
+				case 4:
+					num = va_arg(args, intmax_t);
+					break;
+				case 5:
+					num = va_arg(args, ptrdiff_t);
+					break;
+				default:
+					num = va_arg(args, unsigned int);
+					break;
+			}
+			
+			// Get the length of the printed number
+			unsigned int len = numLen(num, 16);
+			
+			// Get the length of the printed number with formatting
+			unsigned int flen = len;
+			if (precision > len)
+				flen += (precision - len);
+			if ((mode >> 3) % 2 == 1 || (mode >> 4) % 2 == 1)
+				flen++;
+			if ((mode >> 6) % 2 == 1)
+				flen += 2;
+			
+			// If specified, print preceding space padding
+			if ((mode >> 5) % 2 == 0) {
+				if (precision > 0 || (mode >> 7) % 2 == 0) {
+					for (int j = width - flen; j > 0; j--) {
+						term_putChar(term, ' ');
+						numPrinted++;
+					}
+				}
+			}
+			
+			// If specified print the sign
+			if ((mode >> 3) % 2 == 1) {
+				term_putChar(term, '+');
+				numPrinted++;
+			} else if ((mode >> 4) % 2 == 1) {
+				term_putChar(term, ' ');
+				numPrinted++;
+			}
+			
+			// If specified, print the 0x
+			if ((mode >> 6) % 2 == 1) {
+				term_putChar(term, '0');
+				if (fmt[i] == 'x')
+					term_putChar(term, 'x');
+				else
+					term_putChar(term, 'X');
+				numPrinted += 2;
+			}
+			
+			// If specified, print the precision 0s
+			if (precision > 0) {
+				for (int j = precision - len; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			} else if ((mode >> 7) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			}
+			
+			// Print the number
+			if (fmt[i] == 'x')
+				numPrinted += printNum(term, num, 16, BASE16L);
+			else
+				numPrinted += printNum(term, num, 16, BASE16);
+			
+			// If specified, print succeeding spaces
+			if ((mode >> 5) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, ' ');
+					numPrinted++;
+				}
+			}
+			
+			mode = 0;
+			break;
+		// Print an unsigned integer in octal
+		} case 'o': {
+			uintmax_t num;
+			
+			// Pull the argument from the list
+			switch (length) {
+				case 1:
+					num = va_arg(args, unsigned long);
+					break;
+				case 2:
+					num = va_arg(args, unsigned long long);
+					break;
+				case 3:
+					num = va_arg(args, size_t);
+					break;
+				case 4:
+					num = va_arg(args, intmax_t);
+					break;
+				case 5:
+					num = va_arg(args, ptrdiff_t);
+					break;
+				default:
+					num = va_arg(args, unsigned int);
+					break;
+			}
+			
+			// Get the length of the printed number
+			unsigned int len = numLen(num, 8);
+			
+			// Get the length of the printed number with formatting
+			unsigned int flen = len;
+			if (precision > len)
+				flen += (precision - len);
+			if ((mode >> 3) % 2 == 1 || (mode >> 4) % 2 == 1)
+				flen++;
+			if ((mode >> 6) % 2 == 1)
+				flen++;
+			
+			// If specified, print preceding space padding
+			if ((mode >> 5) % 2 == 0) {
+				if (precision > 0 || (mode >> 7) % 2 == 0) {
+					for (int j = width - flen; j > 0; j--) {
+						term_putChar(term, ' ');
+						numPrinted++;
+					}
+				}
+			}
+			
+			// If specified print the sign
+			if ((mode >> 3) % 2 == 1) {
+				term_putChar(term, '+');
+				numPrinted++;
+			} else if ((mode >> 4) % 2 == 1) {
+				term_putChar(term, ' ');
+				numPrinted++;
+			}
+			
+			// If specified, print the 0x
+			if ((mode >> 6) % 2 == 1) {
+				term_putChar(term, '0');
+				numPrinted++;
+			}
+			
+			// If specified, print the precision 0s
+			if (precision > 0) {
+				for (int j = precision - len; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			} else if ((mode >> 7) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, '0');
+					numPrinted++;
+				}
+			}
+			
+			// Print the number
+			numPrinted += printNum(term, num, 8, BASE16);
+			
+			// If specified, print succeeding spaces
+			if ((mode >> 5) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, ' ');
+					numPrinted++;
+				}
+			}
+			
+			mode = 0;
+			break;
+		// Print a string
+		} case 's': {
+			char *s = va_arg(args, char *);
+			term_writeStr(term, s);
+			numPrinted += strlen(s);
+			mode = 0;
+			break;
+		// Print a character
+		} case 'c':
+			if (mode % 2 == 0)
+				term_putChar(term, 'c');
+			else
+				term_putChar(term, (char) va_arg(args, int));
+			
+			numPrinted++;
+			mode = 0;
+			break;
+		// Print a pointer
+		case 'p': {
+			uintmax_t num = va_arg(args, void *);
+			
+			// Get the length of the printed number
+			unsigned int len = numLen(num, 16);
+			unsigned int flen = len + 2;
+			precision = sizeof(void *) * 2; // A byte is 2 hex chars
+			
+			// If specified, print preceding space padding
+			if ((mode >> 5) % 2 == 0) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, ' ');
+					numPrinted++;
+				}
+			}
+			
+			term_putChar(term, '0');
+			term_putChar(term, 'x');
+			numPrinted += 2;
+			
+			// If specified, print the precision 0s
+			for (int j = precision - len; j > 0; j--) {
+				term_putChar(term, '0');
+				numPrinted++;
+			}
+			
+			// Print the number
+			numPrinted += printNum(term, num, 16, BASE16);
+			
+			// If specified, print succeeding spaces
+			if ((mode >> 5) % 2 == 1) {
+				for (int j = width - flen; j > 0; j--) {
+					term_putChar(term, ' ');
+					numPrinted++;
+				}
+			}
+			
+			mode = 0;
+			break;
+		} default:
+			term_putChar(term, fmt[i]);
+			numPrinted++;
+			mode = 0;
+			break;
+		}
+	}
+	
+	va_end(args);
+	return numPrinted;
+}

lib/string.c

@@ -0,0 +1,12 @@
+#include <stddef.h>
+
+#include <brados/string.h>
+
+// Find the length of a string
+size_t strlen(const char *str)
+{
+	size_t len = 0;
+	while (str[len] != 0)
+		len++;
+	return len;
+}