Floppy disk controller, new keyboard and PIT driver interface, many things

- Implemented basic FDC capable of reading floppy disc sectors
 - Now PIT timer can be used, as it counts the ticks
 - Now the keyboard is buffered, instead of being accessed only during the interrupt itself
 - HAL for sleep()
 - gets()
 - atoi()
 - Now shell is not called by the IRQ, but it's a procedure that reads the key buffer

src/kernel/arch/i686/fdc.c

@@ -0,0 +1,240 @@
+#include <stdbool.h>
+#include "fdc.h"
+#include "isr.h"
+#include "io.h"
+#include "../../lib/time.h"
+
+static volatile bool g_fdc_irq = false;
+static int g_curr_drive = 0;
+
+static void i686_fdc_irq(registers *regs){
+    g_fdc_irq = true;
+}
+
+static inline void wait_irq(){
+    while(!g_fdc_irq); // Wait until g_fdc_irq is true
+    g_fdc_irq = false; // Then reset it to false
+}
+
+void i686_fdc_initialize_dma(){
+    i686_outb(0x0A, 0x06); // Mask DMA channel 2
+    i686_outb(0xD8, 0xFF); // Reset master flip-flop
+    i686_outw(0x04, 0x1000); // Address = 0x1000
+    i686_outb(0xD8, 0xFF); // Reset master flip-flop
+    i686_outb(0x05, 0xFF); // Count to 0x23FF (bytes in 2.5" floppy disk track)
+    i686_outb(0x05, 0x23);
+    i686_outb(0x80, 0x00); // External page register = 0
+    i686_outb(0x0A, 0x02); // Unmask DMA channel 2
+}
+
+void i686_fdc_dma_read(){
+    i686_outb(0x0A, 0x06); // Mask DMA channel 2
+    i686_outb(0x0B, 0x56); // single transfer, address increment, autoinit, read, channel 2
+    i686_outb(0x0A, 0x02); // Unmask DMA channel 2
+}
+
+void i686_fdc_dma_write(){
+    i686_outb(0x0A, 0x06); // Mask DMA channel 2
+    i686_outb(0x0B, 0x5A); // single transfer, address increment, autoinit, write, channel 2
+    i686_outb(0x0A, 0x02); // Unmask DMA channel 2
+}
+
+uint8_t i686_fdc_msr_read(){
+    return i686_inb(i686_FDC_MSR);
+}
+
+void i686_fdc_send_cmd(uint8_t cmd){
+    while(!(i686_fdc_msr_read() & i686_FDC_MSR_DATAREG));
+    i686_outb(i686_FDC_FIFO, cmd);
+}
+
+uint8_t i686_fdc_read_data(){
+    while(!(i686_fdc_msr_read() & i686_FDC_MSR_DATAREG));
+    return i686_inb(i686_FDC_FIFO);
+}
+
+void i686_fdc_write_ccr(uint8_t v){
+    i686_outb(i686_FDC_CTRL, v);
+}
+
+void i686_fdc_drive_data(uint32_t stepr, uint32_t loadt, uint32_t unloadt, bool dma){
+    uint32_t data = 0;
+    
+    i686_fdc_send_cmd(i686_FDC_CMD_SPECIFY);
+    
+    data = ((stepr & 0xF) << 4) | (unloadt & 0xF);
+    i686_fdc_send_cmd(data);
+    
+    data = loadt << 1 | dma ? 1 : 0; // Ensure dma is a 0/1 bool
+    i686_fdc_send_cmd(data);
+}
+
+void i686_fdc_check_int(uint32_t *st0, uint32_t *cyl){
+    i686_fdc_send_cmd(i686_FDC_CMD_CHECK_INT);
+    *st0 = i686_fdc_read_data();
+    *cyl = i686_fdc_read_data();
+}
+
+int i686_fdc_motor(bool b){
+    if(g_curr_drive > 3) return -2;
+
+    uint32_t motor = 0;
+    switch(g_curr_drive){
+        case 0: motor = i686_FDC_DOR_DRIVE0_MOTOR; break;
+        case 1: motor = i686_FDC_DOR_DRIVE1_MOTOR; break;
+        case 2: motor = i686_FDC_DOR_DRIVE2_MOTOR; break;
+        case 3: motor = i686_FDC_DOR_DRIVE3_MOTOR; break;
+    }
+
+    if(b) i686_outb(i686_FDC_DOR, g_curr_drive | motor | i686_FDC_DOR_RESET | i686_FDC_DOR_DMA);
+    else i686_outb(i686_FDC_DOR, i686_FDC_DOR_RESET);
+
+    // Give the motor some time
+    sleep(20);
+}
+
+void i686_fdc_read_sector_imp(uint8_t head, uint8_t track, uint8_t sector){
+    uint32_t st0, cyl;
+
+    // Set DMA for read
+    i686_fdc_dma_read();
+
+    // Read a sector
+    i686_fdc_send_cmd(i686_FDC_CMD_READ_SECT | i686_FDC_CMD_EXT_MULTITRACK | i686_FDC_CMD_EXT_SKIP | i686_FDC_CMD_EXT_DENSITY);
+    i686_fdc_send_cmd(head << 2 | g_curr_drive);
+    i686_fdc_send_cmd(track);
+    i686_fdc_send_cmd(head);
+    i686_fdc_send_cmd(sector);
+    i686_fdc_send_cmd(i686_FDC_SECTOR_DTL_512);
+    i686_fdc_send_cmd((sector + 1) >= i686_FDC_SECTORS_PER_TRACK ? i686_FDC_SECTORS_PER_TRACK : sector + 1);
+    i686_fdc_send_cmd(i686_FDC_GAP3_3_5);
+    i686_fdc_send_cmd(0xFF);
+
+    // Wait for IRQ
+    wait_irq();
+
+    // Read output
+    for(int i = 0; i < 7; i++) i686_fdc_read_data();
+
+    // Tell the FDC we are done
+    i686_fdc_check_int(&st0, &cyl);
+}
+
+static void lba_to_chs(int lba, int *head, int *track, int *sector){
+    *head = (lba % (i686_FDC_SECTORS_PER_TRACK * 2)) / i686_FDC_SECTORS_PER_TRACK;
+    *track = lba / (i686_FDC_SECTORS_PER_TRACK * 2);
+    *sector = lba % i686_FDC_SECTORS_PER_TRACK + 1;
+}
+
+uint8_t *i686_fdc_read_sector(int lba){
+    if(g_curr_drive > 3) return 0;
+
+    // Convert LBA to CHS
+    int head = 0, track = 0, sector = 1;
+    lba_to_chs(lba, &head, &track, &sector);
+
+    // Turn on motor and seek
+    i686_fdc_motor(true);
+    if(i686_fdc_seek(track, head) != 0) return 0;
+
+    // Read and turn off motor
+    i686_fdc_read_sector_imp(head, track, sector);
+    i686_fdc_motor(false);
+
+    return (uint8_t *)0x1000;
+}
+
+int i686_fdc_calibrate(uint32_t drive){
+    uint32_t st0, cyl;
+
+    if(drive > 3) return -2;
+
+    i686_fdc_motor(true);
+
+    for(int i = 0; i < 10; i++){
+        // Send command
+        i686_fdc_send_cmd(i686_FDC_CMD_CALIBRATE);
+        i686_fdc_send_cmd(drive);
+        wait_irq();
+        i686_fdc_check_int(&st0, &cyl);
+
+        if(!cyl){
+            i686_fdc_motor(false);
+            return 0;
+        }
+    }
+
+
+    i686_fdc_motor(false);
+    return -1;
+}
+
+int i686_fdc_seek(uint32_t cyl, uint32_t head){
+    uint32_t st0, cyl0;
+
+    if(g_curr_drive > 3) return -2;
+
+    for(int i = 0; i < 10; i++){
+        // Send the command
+        i686_fdc_send_cmd(i686_FDC_CMD_SEEK);
+        i686_fdc_send_cmd(head << 2 | g_curr_drive);
+        i686_fdc_send_cmd(cyl);
+
+        // Wait for the results
+        wait_irq();
+        i686_fdc_check_int(&st0, &cyl0);
+
+        // Found?
+        if(cyl0 == cyl) return 0;
+    }
+
+    return -1;
+}
+
+void i686_fdc_disable(){
+    i686_outb(i686_FDC_DOR, 0);
+}
+
+void i686_fdc_enable(){
+    i686_outb(i686_FDC_DOR, i686_FDC_DOR_RESET | i686_FDC_DOR_DMA);
+}
+
+void i686_fdc_reset(){
+    uint32_t st0, cyl;
+
+    // Reset the controller
+    i686_fdc_disable();
+    i686_fdc_enable();
+    wait_irq();
+
+    // CHECK_INT to all drives
+    for(int i = 0; i < 4; i++) i686_fdc_check_int(&st0, &cyl);
+
+    // 500kb/s
+    i686_fdc_write_ccr(0);
+
+    // steprate = 3ms, unload time = 240ms, load time = 16ms, dma = true
+    i686_fdc_drive_data(3, 16, 240, true);
+
+    // Calibrate the disk
+    i686_fdc_calibrate(g_curr_drive);
+}
+
+void i686_fdc_set_working_drive(int drive){
+    if(drive < 4) g_curr_drive = drive;
+}
+
+void i686_fdc_initialize(){
+    debug_printf("[FDC] Initializing\n");
+    // Setup IRQ
+    i686_isr_register_handler(IRQ(6), i686_fdc_irq);
+
+    // Initialize DMA
+    i686_fdc_initialize_dma();
+
+    // Reset FDC
+    i686_fdc_reset();
+
+    // Set drive info
+    i686_fdc_drive_data(13, 1, 0x0F, true);
+}

src/kernel/arch/i686/fdc.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#define i686_FDC_DOR 0x3F2
+#define i686_FDC_MSR 0x3F4
+#define i686_FDC_FIFO 0x3F5
+#define i686_FDC_CTRL 0x3F7
+#define i686_FDC_DOR_DRIVE0 0x00
+#define i686_FDC_DOR_DRIVE1 0x01
+#define i686_FDC_DOR_DRIVE2 0x02
+#define i686_FDC_DOR_DRIVE3 0x03
+#define i686_FDC_DOR_RESET 0x04
+#define i686_FDC_DOR_DMA 0x08
+#define i686_FDC_DOR_DRIVE0_MOTOR 0x10
+#define i686_FDC_DOR_DRIVE1_MOTOR 0x20
+#define i686_FDC_DOR_DRIVE2_MOTOR 0x40
+#define i686_FDC_DOR_DRIVE3_MOTOR 0x80
+#define i686_FDC_MSR_DRIVE0_POS_MODE 0x01
+#define i686_FDC_MSR_DRIVE1_POS_MODE 0x02
+#define i686_FDC_MSR_DRIVE2_POS_MODE 0x04
+#define i686_FDC_MSR_DRIVE3_POS_MODE 0x08
+#define i686_FDC_MSR_BUSY 0x10
+#define i686_FDC_MSR_DMA 0x20
+#define i686_FDC_MSR_DATAIO 0x40
+#define i686_FDC_MSR_DATAREG 0x80
+#define i686_FDC_CMD_READ_TRACK 0x02
+#define i686_FDC_CMD_SPECIFY 0x03
+#define i686_FDC_CMD_CHECK_STAT 0x04
+#define i686_FDC_CMD_WRITE_SECT 0x05
+#define i686_FDC_CMD_READ_SECT 0x06
+#define i686_FDC_CMD_CALIBRATE 0x07
+#define i686_FDC_CMD_CHECK_INT 0x08
+#define i686_FDC_CMD_WRITE_DEL_S 0x09
+#define i686_FDC_CMD_READ_ID_S 0x0A
+#define i686_FDC_CMD_READ_DEL_S 0x0C
+#define i686_FDC_CMD_FORMAT_TRACK 0x0D
+#define i686_FDC_CMD_SEEK 0x0F
+#define i686_FDC_CMD_EXT_SKIP 0x20
+#define i686_FDC_CMD_EXT_DENSITY 0x40
+#define i686_FDC_CMD_EXT_MULTITRACK 0x80
+#define i686_FDC_GAP3_STD 42
+#define i686_FDC_GAP3_5_14 32
+#define i686_FDC_GAP3_3_5 27
+#define i686_FDC_SECTOR_DTL_128 0
+#define i686_FDC_SECTOR_DTL_256 1
+#define i686_FDC_SECTOR_DTL_512 2
+#define i686_FDC_SECTOR_DTL_1024 4
+#define i686_FDC_SECTORS_PER_TRACK 18
+
+void i686_fdc_initialize_dma();
+void i686_fdc_dma_read();
+void i686_fdc_dma_write();
+uint8_t i686_fdc_msr_read();
+void i686_fdc_send_cmd(uint8_t cmd);
+uint8_t i686_fdc_read_data();
+void i686_fdc_write_ccr(uint8_t v);
+void i686_fdc_drive_data(uint32_t stepr, uint32_t loadt, uint32_t unloadt, bool dma);
+void i686_fdc_check_int(uint32_t *st0, uint32_t *cyl);
+int i686_fdc_motor(bool b);
+void i686_fdc_read_sector_imp(uint8_t head, uint8_t track, uint8_t sector);
+uint8_t *i686_fdc_read_sector(int lba);
+int i686_fdc_calibrate(uint32_t drive);
+int i686_fdc_seek(uint32_t cyl, uint32_t head);
+void i686_fdc_disable();
+void i686_fdc_enable();
+void i686_fdc_reset();
+void i686_fdc_set_working_drive(int drive);
+void i686_fdc_initialize();

src/kernel/arch/i686/pit.c

@@ -0,0 +1,19 @@
+#include "pit.h"
+#include "isr.h"
+#include "../../lib/stdio.h"
+#include "../../lib/debug.h"
+
+static volatile uint32_t g_tick_count = 0;
+
+static void i686_pit_handler(registers *regs){
+    g_tick_count++;
+}
+
+void i686_pit_initialize(){
+    debug_printf("[PIT] Initializing\n");
+    i686_isr_register_handler(IRQ(0), i686_pit_handler);
+}
+
+uint32_t i686_pit_get_tick_count(){
+    return g_tick_count;
+}

src/kernel/arch/i686/pit.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <stdint.h>
+
+void i686_pit_initialize();
+uint32_t i686_pit_get_tick_count();

src/kernel/drivers/keyboard.c

@@ -11,54 +11,66 @@
 static bool g_caps_lock = false;
 static bool g_shift = false;
 
-static char g_key_buffer[256];
+static struct {
+    char buffer[KEY_BUFFER_LENGTH];
+    int base;
+    int top;
+} g_key_buffer;
+
+void keyboard_buffer_add(char c){
+    g_key_buffer.buffer[g_key_buffer.top] = c;
+    g_key_buffer.top++;
+    g_key_buffer.top %= KEY_BUFFER_LENGTH;
+}
+
+char keyboard_buffer_get(){
+    char c = g_key_buffer.buffer[g_key_buffer.base];
+    g_key_buffer.base++;
+    g_key_buffer.base %= KEY_BUFFER_LENGTH;
+    return c;
+}
+
+int keyboard_buffer_length(){
+    int base = g_key_buffer.base;
+    int top = g_key_buffer.top;
+    if(top < base) top += KEY_BUFFER_LENGTH;
+    return top - base;
+}
 
 static const char g_sc_ascii[128] = {
     '?', '?', '1', '2', '3', '4', '5', '6',
-    '7', '8', '9', '0', '-', '=', '?', '?',
+    '7', '8', '9', '0', '-', '=', '\b', '?',
     'q', 'w', 'e', 'r', 't', 'y', 'u', 'i',
-    'o', 'p', '[', ']', '?', '?', 'a', 's',
+    'o', 'p', '[', ']', '\n', '?', 'a', 's',
     'd', 'f', 'g', 'h', 'j', 'k', 'l', ';',
     '\'', '`', '?', '\\', 'z', 'x', 'c', 'v',
     'b', 'n', 'm', ',', '.', '/', '?', '?',
     '?', ' '
 };
 
-static void user_input(char *str){
-    shell_run(str);
-}
-
 static void keyboard_callback(){
     uint8_t scancode = i686_inb(0x60);
     if(scancode == 0x2A) g_shift = true; // Shift pressed
     else if(scancode == 0x2A + 128) g_shift = false; // Shift released
     else if(scancode == 0x3A) g_caps_lock = !g_caps_lock; // Caps lock pressed
     else if(scancode < 128){ // If it's a "pressed" event, not "released"
-        if(scancode == 0x0E){ // Backspace
-            putc('\b');
-            g_key_buffer[strlen(g_key_buffer)-1] = '\0';
-        }
-        else if(scancode == 0x1C){ // Enter
-            putc('\n');
-            user_input(g_key_buffer);
-            g_key_buffer[0] = '\0';
-        }
-        else{
-            char c = g_sc_ascii[scancode];
-            if(c >= 'a' && c <= 'z' && g_shift != g_caps_lock) c += 'A' - 'a';
-            putc(c);
+        char c = g_sc_ascii[scancode];
+        if(c >= 'a' && c <= 'z' && g_shift != g_caps_lock) c += 'A' - 'a';
 
-            // strlen() works here because char[] is the same as
-            // char*, and both are null-terminated, so they are
-            // exactly the same
-            int len = strlen(g_key_buffer);
-            g_key_buffer[len] = c;
-            g_key_buffer[len+1] = '\0';
-        }
+        // strlen() works here because char[] is the same as
+        // char*, and both are null-terminated, so they are
+        // exactly the same
+        keyboard_buffer_add(c);
     }
 }
 
 void keyboard_initialize(){
-    debug_printf("[KEYBOARD] Initializing keyboard\n");
+    debug_printf("[KEYBOARD] Initializing\n");
+
+    // Setup IRQ
     i686_isr_register_handler(IRQ(1), keyboard_callback);
+
+    // Initialize key buffer
+    g_key_buffer.base = 0;
+    g_key_buffer.top = 0;
 }

src/kernel/drivers/keyboard.h

@@ -1,3 +1,7 @@
 #pragma once
 
+#define KEY_BUFFER_LENGTH 16
+
+char keyboard_buffer_get();
+int keyboard_buffer_length();
 void keyboard_initialize();

src/kernel/drivers/timer.c

@@ -1,13 +0,0 @@
-#include "timer.h"
-#include "../arch/i686/isr.h"
-#include "../lib/stdio.h"
-#include "../lib/debug.h"
-
-static void timer_handler(registers *regs){
-    //printf("TICK\n");
-}
-
-void timer_initialize(){
-    debug_printf("[TIMER] Initializing PIT\n");
-    i686_isr_register_handler(IRQ(0), timer_handler);
-}

src/kernel/drivers/timer.h

@@ -1,3 +0,0 @@
-#pragma once
-
-void timer_initialize();

src/kernel/hal/hal.c

@@ -2,9 +2,15 @@
 #include "../arch/i686/gdt.h"
 #include "../arch/i686/idt.h"
 #include "../arch/i686/isr.h"
+#include "../arch/i686/pit.h"
 
 void hal_initialize(){
     i686_gdt_initialize();
     i686_idt_initialize();
     i686_isr_initialize();
+    i686_pit_initialize();
+}
+
+uint32_t hal_get_tick_count(){
+    return i686_pit_get_tick_count();
 }

src/kernel/hal/hal.h

@@ -1,3 +1,6 @@
 #pragma once
 
+#include <stdint.h>
+
 void hal_initialize();
+uint32_t hal_get_tick_count();

src/kernel/lib/stdio.c

@@ -3,6 +3,7 @@
 #include "stdio.h"
 #include "../drivers/vga.h"
 #include "../drivers/uart.h"
+#include "../drivers/keyboard.h"
 
 typedef void (*print_callable_fn_t)(char);
 
@@ -128,6 +129,34 @@ void serial_printf(char *fmt, ...){
     _vprintf(serial_putc, fmt, args);
 }
 
+void gets(char *str, int max){
+    int count = 0;
+    str[0] = '\0';
+
+    for(;;){
+        if(keyboard_buffer_length()){
+            char c = keyboard_buffer_get();
+            if(c == '\n'){
+                putc(c);
+                return;
+            }
+            else if(c == '\b'){
+                if(count){
+                    putc(c);
+                    str[count--] = '\0';
+                }
+            }
+            else{
+                if(count < max){
+                    putc(c);
+                    str[count] = c;
+                    str[++count] = '\0';
+                }
+            }
+        }
+    }
+}
+
 void clear_screen(){
     vga_fill_screen(' ', VGA_COLOR_BG_BLACK | VGA_COLOR_FG_WHITE);
     vga_set_cursor(0);

src/kernel/lib/stdio.h

@@ -9,4 +9,5 @@ void vprintf(char *fmt, va_list args);
 void printf(char *fmt, ...);
 void serial_vprintf(char *fmt, va_list args);
 void serial_printf(char *fmt, ...);
+void gets(char *str, int max);
 void clear_screen();

src/kernel/lib/string.c

@@ -17,3 +17,14 @@ void strcpy(char *dest, char *src){
     }
     *dest = '\0';
 }
+
+int atoi(char *str){
+    int res = 0;
+
+    for(int i = 0; i < strlen(str); i++){
+        res *= 10;
+        res += str[i] - '0';
+    }
+
+    return res;
+}

src/kernel/lib/string.h

@@ -3,3 +3,4 @@
 int strlen(char *s);
 int strcmp(char *s1, char *s2);
 void strcpy(char *dest, char *src);
+int atoi(char *str);

src/kernel/lib/time.c

@@ -0,0 +1,8 @@
+#include <stdint.h>
+#include "time.h"
+#include "../hal/hal.h"
+
+void sleep(int ms){
+    uint32_t ticks = ms + hal_get_tick_count();
+    while(ticks > hal_get_tick_count());
+}

src/kernel/lib/time.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void sleep(int ms);

src/kernel/main.c

@@ -1,7 +1,6 @@
 #include <stdint.h>
 #include "lib/stdio.h"
 #include "hal/hal.h"
-#include "drivers/timer.h"
 #include "drivers/keyboard.h"
 #include "drivers/uart.h"
 #include "fs/vfs.h"
@@ -9,6 +8,7 @@
 #include "arch/i686/mm/vmm.h"
 #include "multiboot.h"
 #include "lib/debug.h"
+#include "arch/i686/fdc.h"
 
 extern uint8_t end; // Kernel end
 
@@ -23,7 +23,6 @@ void __attribute__((cdecl)) kmain(multiboot_info_t *multiboot_info){
     uart_initialize(COM1, 2);
 
     // Initialize drivers
-    timer_initialize();
     keyboard_initialize();
 
     // Initialize physical memory manager
@@ -31,6 +30,8 @@ void __attribute__((cdecl)) kmain(multiboot_info_t *multiboot_info){
 
     i686_pmm_initialize(mem_size, (int)(&end));
 
+    // Memory map
+    debug_printf("= Memory map =\n");
     for(int i = 0; i < multiboot_info->mmap_length; i += sizeof(multiboot_memory_map_t)){
         multiboot_memory_map_t *memory_map = (multiboot_memory_map_t *)(multiboot_info->mmap_addr + i);
         debug_printf("Start Addr: 0x%x%x | Length: 0x%x%x | Size: 0x%x | Type: %i\n", memory_map->addr_h, memory_map->addr_l, memory_map->len_h, memory_map->len_l, memory_map->size, memory_map->type);
@@ -45,8 +46,17 @@ void __attribute__((cdecl)) kmain(multiboot_info_t *multiboot_info){
     // Initialize virtual memory
     i686_vmm_initialize();
     
+    // Floppy disk controller
+    i686_fdc_set_working_drive(0);
+    i686_fdc_initialize();
+
     // Initialize FS
     vfs_initialize();
     
+    // Run shell
+    shell();
+
+    // Halt at end
+    debug_printf("Kernel execution ended\n");
     for(;;);
 }

src/kernel/shell.c

@@ -1,7 +1,10 @@
+#include <stdint.h>
 #include "shell.h"
 #include "lib/stdio.h"
 #include "lib/string.h"
 #include "lib/memory.h"
+#include "lib/time.h"
+#include "arch/i686/fdc.h"
 
 int shell_run(char *cmd){
     int ret = 0;
@@ -19,6 +22,35 @@ int shell_run(char *cmd){
     else if(!strcmp(cmd, "serial")){
         serial_printf("Hello world!\n");
     }
+    else if(!strcmp(cmd, "sleep")){
+        printf("Sleeping...\n");
+        sleep(25);
+        printf("Done!\n");
+    }
+    else if(!strcmp(cmd, "readsect")){
+        puts("Sector number: ");
+        char secn_str[4];
+        gets(secn_str, 3);
+        int secn = atoi(secn_str);
+
+        uint8_t *sector = i686_fdc_read_sector(secn);
+
+        if(sector){
+            int i = 0;
+            for(int c = 0; c < 4; c++){
+                for(int j = 0; j < 128; j++){
+                    printf("0x%x ", sector[i+j]);
+                }
+                i += 128;
+                printf("\nPress enter to continue\n");
+                gets(NULL, NULL);
+            }
+        }
+        else{
+            printf("ERROR reading sector %i from disk", secn);
+        }
+        printf("Done!\n");
+    }
     else{
         printf("SHELL: Unknown command \"%s\"\n", cmd);
         ret = 127;
@@ -27,3 +59,14 @@ int shell_run(char *cmd){
     
     return ret;
 }
+
+void shell(){
+    puts("\x1b[33mWelcome to quark!\x1b[0m\n\n");
+
+    for(;;){
+        static char cmd_buffer[256];
+        puts("$>");
+        gets(cmd_buffer, 255);
+        shell_run(cmd_buffer);
+    }
+}

src/kernel/shell.h

@@ -1,3 +1,3 @@
 #pragma once
 
-int shell_run();
+void shell();