FAT16 directory enumeration, making many functions static, new 'log' functions to wrap vga and serial

19 files changed, 434 insertions, 251 deletions

diff --git a/fs-skel/test.txt b/fs-skel/test.txt
new file mode 100644
index 0000000..d6d9d34
--- /dev/null
+++ b/fs-skel/test.txt
@@ -0,0 +1 @@
+blah
\ No newline at end of file
diff --git a/makefile b/makefile
index 2152dde..502a3cc 100644
--- a/makefile
+++ b/makefile
@@ -39,7 +39,9 @@ kernel:
 	gcc ${kgccargs} -c src/kernel/drive.c  -o obj/kernel/drive.o
 	gcc ${kgccargs} -c src/kernel/fat.c    -o obj/kernel/fat.o
 	gcc ${kgccargs} -c src/kernel/ide.c    -o obj/kernel/ide.o
+	gcc ${kgccargs} -c src/kernel/log.c    -o obj/kernel/log.o
 	gcc ${kgccargs} -c src/kernel/main.c   -o obj/kernel/main.o
+	gcc ${kgccargs} -c src/kernel/main2.c  -o obj/kernel/main2.o
 	gcc ${kgccargs} -c src/kernel/mem.c    -o obj/kernel/mem.o
 	gcc ${kgccargs} -c src/kernel/panic.c  -o obj/kernel/panic.o
 	gcc ${kgccargs} -c src/kernel/pci.c    -o obj/kernel/pci.o
@@ -47,7 +49,6 @@ kernel:
 	gcc ${kgccargs} -c src/kernel/serial.c -o obj/kernel/serial.o
 	gcc ${kgccargs} -c src/kernel/task.c   -o obj/kernel/task.o
 	gcc ${kgccargs} -c src/kernel/util.c   -o obj/kernel/util.o
-	gcc ${kgccargs} -c src/kernel/vesa.c   -o obj/kernel/vesa.o
 	gcc ${kgccargs} -c src/kernel/vga.c    -o obj/kernel/vga.o
 	ld -T src/kernel/elf-link.ld obj/kernel/*.o -o obj/kernel.elf
 	objcopy -O binary obj/kernel.elf out/kernel.bin
diff --git a/src/boot.asm b/src/boot.asm
index eb3b2c9..c74145c 100644
--- a/src/boot.asm
+++ b/src/boot.asm
@@ -5,13 +5,12 @@ kernel_sectors equ 64
 kernel_segment equ 0x3000
 
 support_flags equ 0x4000
-pci_hw_char equ 0x4001
-pci_ver equ 0x4002
+pci_hw_char   equ 0x4001
+pci_ver       equ 0x4002
+last_pci_bus  equ 0x4004
 
 pci_support equ 0x80
 
-vesa_segment equ 0x0420
-
   in al, 0x92
   or al, 0x02
   out 0x92, al
@@ -44,19 +43,9 @@ vesa_segment equ 0x0420
   mov byte [support_flags], pci_support
   mov byte [pci_hw_char], al
   mov word [pci_ver], bx
+  mov byte [last_pci_bus], cl
 
 no_pci:
-  mov dword [vesa_segment * 16], 'V' + 'B' * 256 + 'E' * 65535 + '2' * 16777216
-
-  mov ax, vesa_segment
-  mov es, ax
-  xor di, di
-  mov ax, 0x4f00
-  int 0x10
-
-  cmp ax, 0x004f
-  jne no_vbe
-
   cli
 
   lgdt [gdt]
@@ -67,15 +56,6 @@ no_pci:
 
   jmp 0x08:pmode
 
-no_vbe:
-  ;TODO
-
-  cli
-
-real_halt:
-  hlt
-  jmp real_halt
-
 bits 32
 
 pmode:
diff --git a/src/kernel/drive.c b/src/kernel/drive.c
index b001aca..38fef38 100644
--- a/src/kernel/drive.c
+++ b/src/kernel/drive.c
@@ -5,23 +5,34 @@
 uint8_t n_drives = 0;
 struct drive drives[256];
 
-__attribute__ ((const)) drive_file_id_t unknown_get_file(const struct drive *d, const char *path) {
+__attribute__ ((const))
+static drive_file_id_t unknown_get_file(const struct drive *d, const char *path) {
   return 0;
 }
 
-void unknown_free_file(const struct drive *d, drive_file_id_t fid) {
+static void unknown_free_file(const struct drive *d, drive_file_id_t fid) {
   panic("Free file called on unknown file system");
 }
 
-void unknown_load_sector(const struct drive *d, drive_file_id_t fid, uint32_t sector, void *at) {
+static void unknown_load_sector(const struct drive *d, drive_file_id_t fid, uint32_t sector, void *at) {
   panic("Load sector called on unknown file system");
 }
 
-__attribute__ ((const)) uint32_t unknown_get_free_sectors(const struct drive *d) {
+static uint32_t unknown_get_file_length(const struct drive *d, drive_file_id_t fid) {
+  panic("Get file length called on unknown file system");
+}
+
+__attribute__ ((const))
+static uint32_t unknown_get_free_sectors(const struct drive *d) {
   return -1;
 }
 
-void determine_fs(struct drive *d) {
+__attribute__ ((const))
+static uint32_t unknown_enumerate_dir(const struct drive *d, const char *path, struct directory_content_info *info, uint32_t max) {
+  return 0;
+}
+
+static void determine_fs(struct drive *d) {
   if (try_fat_init_drive(d))
     return;
 
@@ -29,6 +40,8 @@ void determine_fs(struct drive *d) {
   d->get_file = &unknown_get_file;
   d->free_file = &unknown_free_file;
   d->load_sector = &unknown_load_sector;
+  d->get_file_length = &unknown_get_file_length;
+  d->enumerate_dir = &unknown_enumerate_dir;
   d->get_free_sectors = &unknown_get_free_sectors;
 }
 
diff --git a/src/kernel/drive.h b/src/kernel/drive.h
index ca6d1ee..8eb6955 100644
--- a/src/kernel/drive.h
+++ b/src/kernel/drive.h
@@ -1,6 +1,7 @@
 #ifndef DRIVE_H
 #define DRIVE_H
 
+#include <stdbool.h>
 #include <stdint.h>
 
 typedef uint8_t drive_file_id_t;
@@ -9,20 +10,29 @@ typedef uint8_t fs_id_t;
 typedef uint8_t drive_id_t;
 
 #define MAX_DRIVES 256
+#define DCI_NAME_LEN 100
+
+struct directory_content_info {
+  bool is_dir;
+  char name[DCI_NAME_LEN];
+  uint32_t size;
+};
 
 struct drive {
   char *drive_type;
   char *fs_type;
 
-  uint8_t (*read_sectors)(const struct drive *d, uint32_t start, uint32_t count, void *buffer);
+  uint8_t (*read_sectors) (const struct drive *d, uint32_t start, uint32_t count, void *buffer);
   uint8_t (*write_sectors)(const struct drive *d, uint32_t start, uint32_t count, const void *buffer);
   uint32_t n_sectors;
   drive_id_t drive_id;
 
-  drive_file_id_t (*get_file)(const struct drive *d, const char *path);
-  void (*free_file)(const struct drive *d, drive_file_id_t fid);
-  void (*load_sector)(const struct drive *d, drive_file_id_t fid, uint32_t sector, void *at);
-  uint32_t (*get_free_sectors)(const struct drive *d);
+  drive_file_id_t (*get_file)        (const struct drive *d, const char *path);
+  void            (*free_file)       (const struct drive *d, drive_file_id_t fid);
+  void            (*load_sector)     (const struct drive *d, drive_file_id_t fid, uint32_t sector, void *at);
+  uint32_t        (*get_file_length) (const struct drive *d, drive_file_id_t fid);
+  uint32_t        (*enumerate_dir)   (const struct drive *d, const char *path, struct directory_content_info *info, uint32_t max);
+  uint32_t        (*get_free_sectors)(const struct drive *d);
   fs_id_t fs_id;
 };
 
diff --git a/src/kernel/fat.c b/src/kernel/fat.c
index 807af00..ff01d7d 100644
--- a/src/kernel/fat.c
+++ b/src/kernel/fat.c
@@ -8,6 +8,9 @@
 #define MAX_FAT_DRIVES 16
 #define MAX_OPEN_FILES_PER_DRIVE 32
 
+#define PATH_SEP_CHAR '/'
+#define EXT_SEP_CHAR '.'
+
 enum {
   FA_READ_ONLY = 0x01,
   FA_HIDDEN    = 0x02,
@@ -59,33 +62,44 @@ struct fat_info {
 
 #define CTOS(c, fdi) ((fdi)->data_start + (c) - 2)
 
+struct open_file_info {
+  //directory entry is the di_number'th entry in the di_sector'th sector
+  //di_sector of 0 indicates an unused handle
+  uint32_t di_sector;
+  uint8_t di_number;
+
+  uint16_t start_cluster;
+  uint32_t length;
+};
+
 struct fat_drive_info {
   const struct fat_info *fi;
   uint16_t *fat;
   uint16_t root_start;
   uint16_t data_start;
-  struct directory_entry open_files[MAX_OPEN_FILES_PER_DRIVE];
+  struct open_file_info open_files[MAX_OPEN_FILES_PER_DRIVE];
 };
 
-struct fat_drive_info infos[MAX_FAT_DRIVES];
-uint8_t next_id = 0;
+static struct fat_drive_info infos[MAX_FAT_DRIVES];
+static uint8_t next_id = 0;
 
-uint8_t fat_driver_buffer[512];
-struct fat_info *next_fi;
+static uint8_t fat_driver_buffer[512];
+static struct fat_info *next_fi;
 
-void alloc_next_fi() {
+static void alloc_next_fi() {
   if (!((uint32_t)(next_fi = (struct fat_info *)((uint32_t)next_fi + 64)) & 0xfff))
     if (!(next_fi = allocate_pages(1)))
       panic("Out of memory in FAT driver.");
 }
 
-const struct drive *cur_drive;
-fs_id_t cur_id;
-const struct fat_drive_info *cur_fdi;
-struct directory_entry *cur_dir;
+static const struct drive *cur_drive;
+static fs_id_t cur_id;
+static const struct fat_drive_info *cur_fdi;
+static struct directory_entry *cur_dir;
+static uint32_t cur_sect;
 
 //loads cluster `c`
-void load_cluster(uint16_t c, void *to) {
+static void load_cluster(uint16_t c, void *to) {
   if (c == 0) {
     *(uint8_t *)to = 0;
     return;
@@ -95,26 +109,29 @@ void load_cluster(uint16_t c, void *to) {
   cur_drive->read_sectors(cur_drive, s, 1, to);
 }
 
-uint16_t next_cluster(uint16_t c) {
+static uint16_t next_cluster(uint16_t c) {
   panic("TODO: compute next sector (or 0 for none)");
 }
 
+static const uint8_t this_dir[]   = {'.', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '};
+static const uint8_t parent_dir[] = {'.', '.', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '};
+
 static inline bool check_fat_names(const uint8_t *a, const uint8_t *b) {
   return (((uint32_t *)a)[0] == ((uint32_t *)b)[0]) &&
          (((uint32_t *)a)[1] == ((uint32_t *)b)[1]) &&
-         (((uint16_t *)a)[8] == ((uint16_t *)b)[8]) &&
+         (((uint16_t *)a)[4] == ((uint16_t *)b)[4]) &&
          (((uint8_t *)a)[10] == ((uint8_t *)b)[10]);
 }
 
 //after: cur_dir -> specified entry in root
-bool try_locate_root_entry(const uint8_t *fat_name) {
-  uint32_t cur_dir_sect = cur_fdi->root_start - 1;
+static bool try_locate_root_entry(const uint8_t *fat_name) {
+  cur_sect = cur_fdi->root_start - 1;
   cur_dir = (struct directory_entry *)(fat_driver_buffer + 512);
   while (true) {
     if (cur_dir == (struct directory_entry *)(fat_driver_buffer + 512)) {
       cur_dir = (struct directory_entry *)fat_driver_buffer;
-      ++cur_dir_sect;
-      cur_drive->read_sectors(cur_drive, cur_dir_sect, 1, cur_dir);
+      ++cur_sect;
+      cur_drive->read_sectors(cur_drive, cur_sect, 1, cur_dir);
     }
     if (!*(uint8_t *)cur_dir)
       return false;
@@ -127,53 +144,109 @@ bool try_locate_root_entry(const uint8_t *fat_name) {
 
 //before: cur_dir -> entry of dir to search
 //after: cur_dir -> specified entry in dir
-bool try_locate_entry(const uint8_t *fat_name) {
+static bool try_locate_entry(const uint8_t *fat_name) {
   uint16_t cur_dir_cluster = cur_dir->first_cluster;
   load_cluster(cur_dir_cluster, fat_driver_buffer);
   cur_dir = (struct directory_entry *)fat_driver_buffer;
   while (true) {
     if (cur_dir == (struct directory_entry *)(fat_driver_buffer + 512)) {
       cur_dir = (struct directory_entry *)fat_driver_buffer;
-      ++cur_dir_cluster;
       load_cluster(cur_dir_cluster = next_cluster(cur_dir_cluster), fat_driver_buffer);
     }
     if (!*(uint8_t *)cur_dir)
       return false;
-    if (check_fat_names(cur_dir -> name, fat_name))
+    if (check_fat_names(cur_dir->name, fat_name)) {
+      cur_sect = CTOS(cur_dir_cluster, cur_fdi);
       return true;
+    }
     else
       ++cur_dir;
   }
 }
 
-drive_file_id_t fat_get_file(const struct drive *d, const char *path) {
+//puts first path component's fat name into fat_name_buffer,
+//returns rest of path
+static const char *split_path(const char *path, uint8_t *fat_name_buffer) {
+  uint8_t pi = 0, fi = 0;
+  while (1) {
+    if ((path[pi] == PATH_SEP_CHAR) || !path[pi]) {
+      while (fi != 11)
+        fat_name_buffer[fi++] = (uint8_t)' ';
+      return path + (path[pi] ? pi + 1 : pi);
+    }
+    if (path[pi] == EXT_SEP_CHAR)
+      if (fi <= 8) {
+        while (fi != 8)
+          fat_name_buffer[fi++] = (uint8_t)' ';
+        ++pi;
+      }
+      else
+        panic("Bad path in FAT16 driver");
+    else if ((fi == 8) || (fi == 11))
+      panic("Bad path in FAT16 driver");
+    else {
+      fat_name_buffer[fi++] = (uint8_t)path[pi++];
+    }
+  }
+}
+
+//cur_dir -> specified entry
+static bool try_load_from_path(const struct drive *d, const char *path) {
   cur_drive = d;
   cur_id = d->drive_id;
   cur_fdi = &infos[cur_id];
-  const struct directory_entry *open_files = cur_fdi->open_files - 1;
+
+  uint8_t fat_name[11];
+  path = split_path(path, fat_name);
+  if (!try_locate_root_entry(fat_name))
+    return false;
+  while (*path) {
+    path = split_path(path, fat_name);
+    if (!try_locate_entry(fat_name))
+      return false;
+  }
+
+  return true;
+}
+
+static drive_file_id_t fat_get_file(const struct drive *d, const char *path) {
+  struct open_file_info *open_files = infos[d->drive_id].open_files - 1;
   for (drive_file_id_t n = 1; n != MAX_OPEN_FILES_PER_DRIVE + 1; ++n)
-    if (!*(uint8_t *)(&open_files[n])) {
-      panic("TODO: open path into open_files[n]");
+    if (!open_files[n].di_sector) {
+      if (!try_load_from_path(d, path))
+        return 0;
+
+      open_files[n].di_sector = cur_sect;
+      open_files[n].di_number = cur_dir - (struct directory_entry *)fat_driver_buffer;
+      open_files[n].start_cluster = cur_dir->first_cluster;
+      open_files[n].length = cur_dir->length;
       return n;
     }
+
   panic("Maximum number of files open reached for FAT drive.");
 }
 
-void fat_free_file(const struct drive *d, drive_file_id_t fid) {
-  *(uint8_t *)(&infos[d->drive_id].open_files[fid - 1]) = 0;
+static void fat_free_file(const struct drive *d, drive_file_id_t fid) {
+  infos[d->drive_id].open_files[fid - 1].di_sector = 0;
 }
 
-void fat_load_sector(const struct drive *d, drive_file_id_t fid, uint32_t sector, void *at) {
+static void fat_load_sector(const struct drive *d, drive_file_id_t fid, uint32_t sector, void *at) {
   cur_drive = d;
   cur_id = d->drive_id;
   cur_fdi = &infos[cur_id];
-  uint16_t c = cur_fdi->open_files[fid - 1].first_cluster;
+  uint16_t c = cur_fdi->open_files[fid - 1].start_cluster;
   for (uint32_t i = 0; i < sector; ++i)
     c = next_cluster(c);
   load_cluster(c, at);
 }
 
-__attribute__ ((pure)) uint32_t fat_get_free_sectors(const struct drive *d) {
+__attribute__ ((pure))
+static uint32_t fat_get_file_length(const struct drive *d, drive_file_id_t fid) {
+  return infos[d->drive_id].open_files[fid - 1].length;
+}
+
+__attribute__ ((pure))
+static uint32_t fat_get_free_sectors(const struct drive *d) {
   uint16_t *start = infos[d->fs_id].fat + 2;
   uint16_t *end = start + d->n_sectors - infos[d->fs_id].data_start;
   uint32_t count = 0;
@@ -183,6 +256,90 @@ __attribute__ ((pure)) uint32_t fat_get_free_sectors(const struct drive *d) {
   return count;
 }
 
+static void fat_name_to_path(const uint8_t *fat_name, char *path) {
+  uint8_t last_visible = -1;
+  for (uint8_t i = 0; i < 8; ++i) {
+    if (fat_name[i] != (uint8_t)' ')
+      last_visible = i;
+    path[i] = (char)fat_name[i];
+  }
+
+  if (fat_name[8] || fat_name[9] || fat_name[10]) {
+    path[last_visible + 1] = EXT_SEP_CHAR;
+    for (uint8_t fi = 8, ti = last_visible + 2; fi < 11; ++fi, ++ti) {
+      if (fat_name[fi] != (uint8_t)' ')
+        last_visible = ti;
+      path[ti] = (char)fat_name[fi];
+    }
+  }
+
+  path[last_visible + 1] = '\0';
+}
+
+static uint32_t enumerate_root(const struct drive *d, struct directory_content_info *info, uint32_t max) {
+  uint32_t sect = infos[d->drive_id].root_start - 1;
+  struct directory_entry *entry = (struct directory_entry *)(fat_driver_buffer + 512);
+  struct directory_content_info *fill = info;
+
+  while (true) {
+    if (entry == (struct directory_entry *)(fat_driver_buffer + 512)) {
+      entry = (struct directory_entry *)fat_driver_buffer;
+      ++sect;
+      d->read_sectors(d, sect, 1, entry);
+    }
+
+    if (!*(uint8_t *)entry || (info == fill + max))
+      return fill - info;
+
+    if (entry-> attrib & FA_LABEL) {
+      ++entry;
+      continue;
+    }
+
+    fill->is_dir = entry->attrib & FA_DIRECTORY;
+    fill->size = entry->length;
+    fat_name_to_path(entry->name, fill->name);
+
+    ++entry;
+    ++fill;
+  }
+}
+
+static uint32_t fat_enumerate_dir(const struct drive *d, const char *path, struct directory_content_info *info, uint32_t max) {
+  if (!*path)
+    return enumerate_root(d, info, max);
+
+  if (!try_load_from_path(d, path))
+    return 0;
+
+  uint16_t cluster = cur_dir->first_cluster;
+  load_cluster(cluster, fat_driver_buffer);
+  struct directory_entry *entry = (struct directory_entry *)fat_driver_buffer;
+  struct directory_content_info *fill = info;
+
+  while (true) {
+    if (entry == (struct directory_entry *)(fat_driver_buffer + 512)) {
+      entry = (struct directory_entry *)fat_driver_buffer;
+      load_cluster(cluster = next_cluster(cluster), fat_driver_buffer);
+    }
+
+    if (!*(uint8_t *)entry || (fill == info + max))
+      return fill - info;
+
+    if (check_fat_names(entry->name, this_dir) || check_fat_names(entry->name, parent_dir)) {
+      ++entry;
+      continue;
+    }
+
+    fill->is_dir = entry->attrib & FA_DIRECTORY;
+    fill->size = entry->length;
+    fat_name_to_path(entry->name, fill->name);
+
+    ++entry;
+    ++fill;
+  }
+}
+
 void init_fat() {
   next_fi = allocate_pages(1);
 }
@@ -203,6 +360,8 @@ bool try_fat_init_drive(struct drive *d) {
   d->get_file = &fat_get_file;
   d->free_file = &fat_free_file;
   d->load_sector = &fat_load_sector;
+  d->get_file_length = &fat_get_file_length;
+  d->enumerate_dir = &fat_enumerate_dir;
   d->get_free_sectors = &fat_get_free_sectors;
 
   d->fs_id = next_id;
@@ -214,9 +373,9 @@ bool try_fat_init_drive(struct drive *d) {
                               ((next_fi->root_entries - 1) >> 4) + 1;
 
   d->read_sectors(d, next_fi->reserved_sectors, next_fi->sectors_per_fat, infos[next_id].fat);
-  struct directory_entry *open_files = infos[next_id].open_files - 1;
+  struct open_file_info *open_files = infos[next_id].open_files - 1;
   for (drive_file_id_t i = 0; i < MAX_OPEN_FILES_PER_DRIVE; ++i)
-    *(uint8_t *)&open_files[i] = 0;
+    open_files[i].di_sector = 0;
 
   alloc_next_fi();
   ++next_id;
diff --git a/src/kernel/ide.c b/src/kernel/ide.c
index a32f149..a4ba34c 100644
--- a/src/kernel/ide.c
+++ b/src/kernel/ide.c
@@ -14,25 +14,13 @@ struct ide_drive_info {
   bool slave;
 };
 
-struct ide_drive_info ide_drives[MAX_IDE_DRIVES];
-drive_id_t n_ide_drives = 0;
+static struct ide_drive_info ide_drives[MAX_IDE_DRIVES];
+static drive_id_t n_ide_drives = 0;
 
 typedef uint16_t spinner_t;
 
 //returns the status after waiting
-uint8_t wait_after_cmd(uint16_t base_port) {
-  for (spinner_t n = -1; n; --n) {
-    uint8_t s = inb(base_port | ATA_REG_STATUS);
-    if (s & ATA_STATUS_ERROR)
-      panic("Error status in IDE driver.");
-    if (!(s & ATA_STATUS_BUSY))
-      return s;
-  }
-  panic("Spun out in IDE driver.");
-}
-
-//returns the status after waiting
-uint8_t wait_for_ready(uint16_t base_port) {
+static uint8_t wait_for_ready(uint16_t base_port) {
   for (spinner_t n = -1; n; --n) {
     uint8_t s = inb(base_port | ATA_REG_STATUS);
     if (s & ATA_STATUS_ERROR)
@@ -44,7 +32,7 @@ uint8_t wait_for_ready(uint16_t base_port) {
 }
 
 //returns the status after waiting
-uint8_t wait_for_error_or_ready(uint16_t base_port) {
+static uint8_t wait_for_error_or_ready(uint16_t base_port) {
   for (spinner_t n = -1; n; --n) {
     uint8_t s = inb(base_port | ATA_REG_STATUS);
     if (s & (ATA_STATUS_DRIVE_READY | ATA_STATUS_ERROR))
@@ -54,7 +42,7 @@ uint8_t wait_for_error_or_ready(uint16_t base_port) {
 }
 
 //returns the status after waiting
-uint8_t wait_for_data_ready_not_busy(uint16_t base_port) {
+static uint8_t wait_for_data_ready_not_busy(uint16_t base_port) {
   for (spinner_t n = -1; n; --n) {
     uint8_t s = inb(base_port | ATA_REG_STATUS);
     if (!(s & ATA_STATUS_BUSY) && (s & ATA_STATUS_DATA_READY))
@@ -65,7 +53,7 @@ uint8_t wait_for_data_ready_not_busy(uint16_t base_port) {
   panic("Spun out in IDE driver.");
 }
 
-uint8_t ide_ata_rs(const struct drive *d, uint32_t start, uint32_t count, void *buffer) {
+static uint8_t ide_ata_rs(const struct drive *d, uint32_t start, uint32_t count, void *buffer) {
   if (start >= d->n_sectors)
     return 0;
   if (start + count > d->n_sectors)
@@ -103,17 +91,17 @@ uint8_t ide_ata_rs(const struct drive *d, uint32_t start, uint32_t count, void *
   return count;
 }
 
-uint8_t ide_ata_ws(const struct drive *d, uint32_t start, uint32_t count, const void *buffer) {
+static uint8_t ide_ata_ws(const struct drive *d, uint32_t start, uint32_t count, const void *buffer) {
   panic("IDE ATA writing not implemented yet");
   return 0;
 }
 
-uint8_t ide_atapi_rs(const struct drive *d, uint32_t start, uint32_t count, void *buffer) {
+static uint8_t ide_atapi_rs(const struct drive *d, uint32_t start, uint32_t count, void *buffer) {
   //panic("IDE ATAPI reading not implemented yet");
   return 0;
 }
 
-uint8_t ide_atapi_ws(const struct drive *d, uint32_t start, uint32_t count, const void *buffer) {
+static uint8_t ide_atapi_ws(const struct drive *d, uint32_t start, uint32_t count, const void *buffer) {
   panic("IDE ATAPI writing not implemented yet");
   return 0;
 }
@@ -124,9 +112,7 @@ struct id_space {
   uint8_t skip2[512 - (120 + 4)];
 } __attribute__ ((__packed__ ));
 
-void vga_printsz(char *s);
-
-void test_drive(uint16_t base_port, uint16_t alt_port, bool slave) {
+static void test_drive(uint16_t base_port, uint16_t alt_port, bool slave) {
   if (n_ide_drives == MAX_IDE_DRIVES)
     panic("Maximum number of IDE drives reached.");
 
diff --git a/src/kernel/log.c b/src/kernel/log.c
new file mode 100644
index 0000000..e8695cc
--- /dev/null
+++ b/src/kernel/log.c
@@ -0,0 +1,25 @@
+#include "vga.h"
+#include "serial.h"
+
+#define INFO_COM COM1
+
+void init_log() {
+  vga_set_color(0x2f);
+  vga_blank();
+}
+
+void logch(char ch) {
+  if (ch == '\n') {
+    sout(INFO_COM, (uint8_t)'\r');
+    sout(INFO_COM, (uint8_t)'\n');
+  }
+  else
+    sout(INFO_COM, (uint8_t)ch);
+
+  vga_printch(ch);
+}
+
+void logsz(const char *sz) {
+  while (*sz)
+    logch(*sz++);
+}
\ No newline at end of file
diff --git a/src/kernel/log.h b/src/kernel/log.h
new file mode 100644
index 0000000..ff2a7a2
--- /dev/null
+++ b/src/kernel/log.h
@@ -0,0 +1,9 @@
+#ifndef LOG_H
+#define LOG_H
+
+void init_log();
+
+void logch(char ch);
+void logsz(const char *sz);
+
+#endif
\ No newline at end of file
diff --git a/src/kernel/main.c b/src/kernel/main.c
index cbdebfa..0c57ef3 100644
--- a/src/kernel/main.c
+++ b/src/kernel/main.c
@@ -3,55 +3,56 @@
 #include "panic.h"
 #include "boot.h"
 #include "util.h"
-#include "vesa.h"
 #include "fat.h"
 #include "ide.h"
 #include "mem.h"
 #include "pci.h"
-#include "vga.h"
+#include "log.h"
 
-__attribute__ ((noreturn)) void main() {
+void tree(struct drive *d);
+
+__attribute__ ((noreturn))
+void main() {
   char nbuf[11];
 
   init_mmap();
-  init_vesa();
   init_serial();
+  init_log();
 
-  vga_blank();
-  vga_printsz("Portland v0.0.11\n\n");
+  logsz("Portland v0.0.11\n\n");
 
   //list vesa modes?
 
   pci_init();
 
   u16_dec(n_pci_devices, nbuf);
-  vga_printsz(nbuf);
-  vga_printsz(" PCI device(s) found:\n");
+  logsz(nbuf);
+  logsz(" PCI device(s) found:\n");
 
   for (uint16_t n = 0; n < n_pci_devices; ++n) {
     struct pci_device *pd = nth_pci_device(n);
 
     u16_hex(pd->number, nbuf);
-    vga_printsz("  ");
-    vga_printsz(nbuf);
-    vga_printsz(": ");
+    logsz("  ");
+    logsz(nbuf);
+    logsz(": ");
 
     u16_hex(pd->id_vendor, nbuf);
     nbuf[4] = '.';
     u16_hex(pd->id_device, nbuf + 5);
-    vga_printsz(nbuf);
+    logsz(nbuf);
 
     u8_hex(pd->class, nbuf);
     nbuf[2] = '.';
     u8_hex(pd->subclass, nbuf + 3);
     nbuf[5] = '.';
     u8_hex(pd->iface, nbuf + 6);
-    vga_printsz(" (");
-    vga_printsz(nbuf);
-    vga_printsz(")\n");
+    logsz(" (");
+    logsz(nbuf);
+    logsz(")\n");
   }
 
-  vga_printch('\n');
+  logch('\n');
 
   init_fat();
   //other fs drivers
@@ -60,49 +61,49 @@ __attribute__ ((noreturn)) void main() {
   //other drive drivers
 
   u8_dec(n_drives, nbuf);
-  vga_printsz(nbuf);
-  vga_printsz(" drive(s) found:\n");
+  logsz(nbuf);
+  logsz(" drive(s) found:\n");
 
   for (uint8_t n = 0; n < n_drives; ++n) {
     struct drive *d = drives + n;
 
     u8_dec(n, nbuf);
-    vga_printsz("  sd");
-    vga_printsz(nbuf);
-    vga_printsz(" (");
-    vga_printsz(d->drive_type);
-    vga_printsz(", ");
+    logsz("  sd");
+    logsz(nbuf);
+    logsz(" (");
+    logsz(d->drive_type);
+    logsz(", ");
 
     u32_dec(d->n_sectors / 2, nbuf);
-    vga_printsz(nbuf);
+    logsz(nbuf);
     if (d->n_sectors % 2)
-      vga_printsz(".5");
-    vga_printsz("k): ");
+      logsz(".5");
+    logsz("k): ");
 
-    vga_printsz(d->fs_type);
+    logsz(d->fs_type);
 
     uint32_t free_sectors = d->get_free_sectors(d);
     if (free_sectors != -1) {
       u32_dec(free_sectors / 2, nbuf);
-      vga_printsz(", ");
-      vga_printsz(nbuf);
+      logsz(", ");
+      logsz(nbuf);
       if (free_sectors % 2)
-        vga_printsz(".5");
-      vga_printsz("k free");
+        logsz(".5");
+      logsz("k free");
     }
 
-    vga_printsz(".\n");
+    logsz(".\n");
   }
 
-  vga_printch('\n');
+  logch('\n');
 
   u32_dec(pages_left * 4, nbuf);
-  vga_printsz(nbuf);
-  vga_printsz("k dynamic memory free.\n\n");
+  logsz(nbuf);
+  logsz("k dynamic memory free.\n\n");
 
-  vga_printsz("Loading init process.");
+  logsz("sd0 root:\n");
+  tree(&drives[0]);
 
-  vga_printsz("\n\nTODO: load and switch to init process");
   while (1)
     asm ("hlt");
 }
\ No newline at end of file
diff --git a/src/kernel/main2.c b/src/kernel/main2.c
new file mode 100644
index 0000000..2b85592
--- /dev/null
+++ b/src/kernel/main2.c
@@ -0,0 +1,59 @@
+#include <stdint.h>
+#include "drive.h"
+#include "util.h"
+#include "log.h"
+
+static char nbuf2[11];
+
+static char path_builder[200] = "";
+static uint8_t path_builder_len = 0;
+
+static char indent_builder[20] = "  ";
+static uint8_t indent_builder_len = 2;
+
+void tree(struct drive *d) {
+  struct directory_content_info infos[100];
+  uint8_t n_infos = d->enumerate_dir(d, path_builder, infos, 100);
+
+  if (!n_infos) {
+    logsz(indent_builder);
+    logsz("(empty)\n");
+    return;
+  }
+
+  for (uint8_t i = 0; i < n_infos; ++i) {
+    logsz(indent_builder);
+    logsz(infos[i].name);
+
+    if (infos[i].is_dir) {
+      logsz(":\n");
+
+      indent_builder[indent_builder_len] = ' ';
+      indent_builder[indent_builder_len + 1] = ' ';
+      indent_builder[indent_builder_len + 2] = '\0';
+      indent_builder_len += 2;
+
+      uint8_t name_length = 0;
+      while (infos[i].name[name_length])
+        ++name_length;
+
+      memcpy(path_builder + path_builder_len, infos[i].name, name_length + 1);
+      path_builder_len += name_length;
+
+      tree(d);
+
+      path_builder_len -= name_length;
+      path_builder[path_builder_len] = '\0';
+
+      indent_builder_len -= 2;
+      indent_builder[indent_builder_len] = '\0';
+    }
+
+    else {
+      u32_dec(infos[i].size, nbuf2);
+      logsz(" (");
+      logsz(nbuf2);
+      logsz(" bytes)\n");
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/kernel/panic.c b/src/kernel/panic.c
index e04ae38..7793065 100644
--- a/src/kernel/panic.c
+++ b/src/kernel/panic.c
@@ -1,12 +1,13 @@
 #include "panic.h"
+#include "log.h"
 #include "vga.h"
 
 void panic(const char *message) {
   vga_set_color(0x4f);
   vga_blank();
-  vga_printsz("Kernel panic: ");
-  vga_printsz(message);
-  vga_printsz("\nHalting.");
+  logsz("Kernel panic: ");
+  logsz(message);
+  logsz("\nHalting.");
   while (1)
     asm volatile ("hlt");
 }
\ No newline at end of file
diff --git a/src/kernel/pci.c b/src/kernel/pci.c
index 5d8170d..28ca6c6 100644
--- a/src/kernel/pci.c
+++ b/src/kernel/pci.c
@@ -10,7 +10,7 @@ enum {
 };
 
 uint16_t n_pci_devices = 0;
-struct pci_device *pci_device_pages[256];
+static struct pci_device *pci_device_pages[256];
 
 #define PCI_DEVICES_PER_PAGE (4096 / sizeof(struct pci_device))
 
@@ -29,20 +29,21 @@ struct pci_device *find_pci_device_from_class_and_subclass(uint8_t class, uint8_
   return 0;
 }
 
-struct pci_device *next_pci_device() {
+static struct pci_device *next_pci_device() {
   if (!(n_pci_devices % PCI_DEVICES_PER_PAGE))
-    pci_device_pages[n_pci_devices / PCI_DEVICES_PER_PAGE] = allocate_pages(1);
+    if (!(pci_device_pages[n_pci_devices / PCI_DEVICES_PER_PAGE] = allocate_pages(1)))
+      panic("Out of memory in PCI enumeration");
   return nth_pci_device(n_pci_devices++);
 }
 
-static inline uint32_t pci_read_config(uint16_t number, uint8_t reg) {
+static uint32_t pci_read_config(uint16_t number, uint8_t reg) {
   uint32_t cspace_addr = 0x80000000 | (number << 8) | (reg << 2);
   outd(PCP_SELECT, cspace_addr);
 
   return ind(PCP_READ);
 }
 
-void pci_device_check(uint16_t number) {
+static void pci_device_check(uint16_t number) {
   uint32_t id = pci_read_config(number, 0);
   if ((id & 0xffff) == 0xffff)
     return;
diff --git a/src/kernel/serial.c b/src/kernel/serial.c
index c92f173..9ca8315 100644
--- a/src/kernel/serial.c
+++ b/src/kernel/serial.c
@@ -48,54 +48,47 @@ enum {
   CLS_READ  = 0x01
 };
 
-bool error;
-#define SERIAL_SPIN_LIMIT 65535
+static const uint16_t ports[] = {
+  CP_1, CP_2, CP_3, CP_4
+};
+
+static bool error[] = {
+  false, false, false, false
+};
 
-bool serr() {
-  return error;
+void reset_error(enum serial_port n) {
+  error[n] = false;
 }
 
 void init_serial() {
-  error = false;
-  outb(CP_1 | CP_INT, 0);
-  outb(CP_1 | CP_LINE, CL_BAUD);
-  outb(CP_1 | CP_DIVLOW, 0x03);//38400
-  outb(CP_1 | CP_DIVHIGH, 0x00);//baud
-  outb(CP_1 | CP_LINE, CL_8BIT);
-  outb(CP_1 | CP_FIFO, 0xc7);//?
+  for (enum serial_port i = COM1; i <= COM4; ++i) {
+    outb(ports[i] | CP_INT, 0);
+    outb(ports[i] | CP_LINE, CL_BAUD);
+    outb(ports[i] | CP_DIVLOW, 0x03);//38400
+    outb(ports[i] | CP_DIVHIGH, 0x00);//baud
+    outb(ports[i] | CP_LINE, CL_8BIT);
+    outb(ports[i] | CP_FIFO, 0xc7);//?
+  }
 }
 
-void sout(char b) {
-  if (error)
+typedef uint16_t serial_spin_t;
+
+void sout(enum serial_port n, uint8_t b) {
+  if (error[n])
     return;
-  uint16_t s = SERIAL_SPIN_LIMIT;
-  while (!(inb(CP_1 | CP_LINE_S) & CLS_WRITE))
-    if (!--s) {
-      error = true;
+  serial_spin_t spinner = -1;
+  while (!(inb(ports[n] | CP_LINE_S) & CLS_WRITE))
+    if (--spinner) {
+      error[n] = true;
       return;
     }
-  outb(CP_1 | CP_DATA, (uint8_t)b);
-}
-
-void soutsz(const char *s) {
-  while (*s)
-    sout(*(s++));
-}
-
-void soutsn(const char *s, uint8_t n) {
-  while (n--)
-    sout(*(s++));
+  outb(ports[n] | CP_DATA, b);
 }
 
-char sin() {
-  if (error)
+uint8_t sin(enum serial_port n) {
+  if (error[n])
     return 0;
-  while (!(inb(CP_1 | CP_LINE_S) & CLS_READ))
+  while (!(inb(ports[n] | CP_LINE_S) & CLS_READ))
     ;//spin
-  return (char)inb(CP_1 | CP_DATA);
-}
-
-void sinsn(char *s, uint8_t n) {
-  while (n--)
-    *(s++) = sin();
+  return inb(ports[n] | CP_DATA);
 }
\ No newline at end of file
diff --git a/src/kernel/serial.h b/src/kernel/serial.h
index 2fb21a6..2ac359d 100644
--- a/src/kernel/serial.h
+++ b/src/kernel/serial.h
@@ -1,15 +1,19 @@
 #ifndef SERIAL_H
 #define SERIAL_H
 
-#include <stdbool.h>
 #include <stdint.h>
 
-bool serr() __attribute__ ((pure));
+enum serial_port {
+  COM1,
+  COM2,
+  COM3,
+  COM4
+};
+
+void reset_error(enum serial_port n);
 void init_serial();
-void sout(char b);
-void soutsz(const char *s);
-void soutsn(const char *s, uint8_t n);
-char sin();
-void sinsn(char *s, uint8_t n);
+
+void sout(enum serial_port n, uint8_t b);
+uint8_t sin(enum serial_port n);
 
 #endif
\ No newline at end of file
diff --git a/src/kernel/vesa.c b/src/kernel/vesa.c
deleted file mode 100644
index 4cdabb2..0000000
--- a/src/kernel/vesa.c
+++ /dev/null
@@ -1,21 +0,0 @@
-#include "vesa.h"
-
-uint16_t screen_width;
-uint16_t screen_height;
-uint8_t bpp;
-
-void *frame_buffer;
-
-void put_pixel(uint16_t x, uint16_t y, color c) {
-
-}
-
-void screen_fill(color c) {
-
-}
-
-void init_vesa() {
-//  for (void *v = 0; v < 0x65536; ++v) {
-//    if (*(uint32_t *)v == 'P' + 'M' * 256 + 'I' * 65536 + 'D' * 16777216)
-//  }
-}
\ No newline at end of file
diff --git a/src/kernel/vesa.h b/src/kernel/vesa.h
deleted file mode 100644
index b2f17c8..0000000
--- a/src/kernel/vesa.h
+++ /dev/null
@@ -1,17 +0,0 @@
-#ifndef VESA_H
-#define VESA_H
-
-#include <stdint.h>
-
-extern uint16_t screen_width;
-extern uint16_t screen_height;
-extern uint8_t bpp;
-
-typedef uint32_t color;
-
-void put_pixel(uint16_t x, uint16_t y, color c);
-void screen_fill(color c);
-
-void init_vesa();
-
-#endif
\ No newline at end of file
diff --git a/src/kernel/vga.c b/src/kernel/vga.c
index e103732..7506416 100644
--- a/src/kernel/vga.c
+++ b/src/kernel/vga.c
@@ -1,61 +1,41 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#define VGA_COM_MIRROR
-
-#ifdef VGA_COM_MIRROR
-#include "serial.h"
-#endif
-
 #define VGA_COLUMNS 80
 #define VGA_LINES 25
 #define VGA_START (uint16_t *)0x000b8000
 #define VGA_END (VGA_START + VGA_COLUMNS * VGA_LINES)
-uint16_t *cursor = VGA_START;
-uint16_t color = 0x1f00;
+static uint16_t *cursor = VGA_START;
+static uint16_t mask;
 
 void vga_set_color(uint8_t new_color) {
-  color = new_color << 8;
+  mask = new_color << 8;
 }
 
 void vga_scroll() {
-  cursor = VGA_START;
+  for (uint32_t *i = (uint32_t *)VGA_START; i < (uint32_t *)(VGA_END - VGA_COLUMNS); ++i)
+    *i = *(i + VGA_COLUMNS / 2);
+  uint32_t f = (mask | (uint8_t)' ') * 0x00010001;
+  for (uint32_t *i = (uint32_t *)(VGA_END - VGA_COLUMNS); i < (uint32_t *)VGA_END; ++i)
+    *i++ = f;
+  cursor -= VGA_COLUMNS;
 }
 
 void vga_blank() {
-#ifdef VGA_COM_MIRROR
-  soutsz("\r\n\r\n<CLEAR>\r\n\r\n");
-#endif
-  uint32_t f = (color << 16) | color | 0x00200020;
+  uint32_t f = (mask | (uint8_t)' ') * 0x00010001;
   uint32_t *p = (uint32_t *)VGA_START;
   while (p < (uint32_t *)VGA_END)
-    *(p++) = f;
+    *p++ = f;
   cursor = VGA_START;
 }
 
 void vga_printch(char ch) {
   if (ch == '\n') {
-#ifdef VGA_COM_MIRROR
-    soutsz("\r\n");
-#endif
     if ((cursor = cursor - (cursor - VGA_START) % VGA_COLUMNS + VGA_COLUMNS) == VGA_END)
       vga_scroll();
     return;
   }
-#ifdef VGA_COM_MIRROR
-  sout(ch);
-#endif
-  *(cursor++) = color | (uint8_t)ch;
+  *cursor++ = mask | (uint8_t)ch;
   if (cursor == VGA_END)
     vga_scroll();
-}
-
-void vga_printsz(const char *sz) {
-  while (*sz)
-    vga_printch(*(sz++));
-}
-
-void vga_printsn(const char *sn, uint8_t n) {
-  while (n--)
-    vga_printch(*(sn++));
 }
\ No newline at end of file
diff --git a/src/kernel/vga.h b/src/kernel/vga.h
index e88ddfe..703080f 100644
--- a/src/kernel/vga.h
+++ b/src/kernel/vga.h
@@ -7,7 +7,5 @@ void vga_set_color(uint8_t color);
 void vga_blank();
 void vga_scroll();
 void vga_printch(char ch);
-void vga_printsz(const char *sz);
-void vga_printsn(const char *sn, uint8_t n);
 
 #endif
\ No newline at end of file