small changes, part 1

doc/design/kernel_functions.txt

@@ -1,4 +0,0 @@
-allocate:
-  ax in: number of pages
-  dx in: process id
-  ebx out: address, or 0x0000_0000 on failure

doc/design/memory_map.txt

@@ -13,8 +13,8 @@
     0x0001 = unavailable
     0x0002 = kernel
     other = process number
-
 0x4000 - 0x6fff : not assigned
+
 0x7000 - 0x7bff : bootloader scratch
   0x7000 : memory map bios buffer
 0x7c00 - 0x7fff : bootloader

makefile

@@ -1,5 +1,5 @@
-floppy: out bootloader files
+floppy: bootloader fs
-	mkfs.fat -C -f 1 -F 12 -n "PORTLAND OS" -R 4 -S 512 out/floppy.img 1440
+	mkfs.fat -C -f 1 -F 12 -n "PORTLAND OS" -R 2 -S 512 out/floppy.img 1440
 	mkdir out/floppy_mount
 	mount out/floppy.img out/floppy_mount
 	cp out/fs/* out/floppy_mount/
@@ -7,16 +7,13 @@ floppy: out bootloader files
 	dd if=obj/bootloader.bin of=out/floppy.img bs=1 seek=62 conv=notrunc
 
 bootloader: obj
-	nasm src/bootloader.bin -o obj/bootloader.bin
+	nasm src/bootloader.asm -o obj/bootloader.bin
 
-kernel: obj out
+kernel: fs
-	gcc -c src/kernel/main.c -o obj/kmain.o -ffreestanding
+	gcc src/kernel/*.c -o out/fs/kernel.sys -ffreestanding -nostdlib -m32 -T src/kernel/link.ld
-	gcc -c src/kernel/vga.c -o obj/kvga.o -ffreestanding
-	ld obj/kmain.o obj/kvga.o -o out/kernel.out -nostdlib --oformat=i386-aout
 
-files: kernel
+fs: out
-	mkdir out/fs
+	mkdir -p out/fs
-	cp out/kernel.out out/fs/kernel.sys
 
 obj:
 	mkdir -p obj

src/bootloader.asm

@@ -24,7 +24,7 @@ fat_header:
 .oem_name            equ 0x7c03;mkfs.fat    - ignored
 .bytes_per_sector    equ 0x7c0b;0x0200      - assumed
 .sectors_per_cluster equ 0x7c0d;0x01        - assumed
-.reserved_sectors    equ 0x7c0e;0x0004      - other values handled
+.reserved_sectors    equ 0x7c0e;0x0002      - handled
 .n_fats              equ 0x7c10;0x01        - assumed
 .root_dir_entries    equ 0x7c11;            -
 .n_sectors           equ 0x7c13;0x0b40      -
@@ -231,6 +231,12 @@ load_kernel:
   mov word [dap.offset], bx
   xor bx, bx
   shr ebx, 4
+  jmp .over_sig
+
+times $$ + 0x01fe - $ db 0
+dw 0xaa55
+
+.over_sig:
   test ebx, 0xffff_0000
   jnz halt
   mov word [dap.segment], bx
@@ -269,9 +275,7 @@ load_kernel:
 
   mov ebx, dword [pointers.kernel]
 
-  ;Parse kernel executable header,
+  ;TODO
-  ;Go through relocation tables,
-  ;Get kernel_start.
 
   cli
 
@@ -292,7 +296,7 @@ dq 0x00c0_9200_8000_0ff7
 
 dap:
 dw 0x0010
-.length  dw 0x0003
+.length  dw 0x0001
 .offset  dw 0x7e00
 .segment dw 0x0000
 .start   dd 0x0000_0001

src/kernel/link.ld

@@ -0,0 +1,11 @@
+OUTPUT_FORMAT(binary)
+SECTIONS {
+  . = 0x01000000;
+  .text : {
+    main = .;
+    *(.text)
+  }
+  .rodata : { *(.rodata) }
+  .data : { *(.data) }
+  .bss : { *(.bss) }
+}

src/kernel/main.c

@@ -24,12 +24,14 @@ OF THIS SOFTWARE.
 #include "misc.h"
 
 void main(void) {
+  *(uint16_t *)0x0000200e = 0x0000;
+
   *(uint32_t *)0x0000050c = (uint32_t)allocate_pages(16 * sizeof(struct file_handle_info), 2);
   for (struct file_handle_info *i = FILE_HANDLES, *l = FILE_HANDLES + 65536; i < l; ++i)
     i->first_sector = 0;
 
   *(uint32_t *)0x00000510 = (uint32_t)allocate_pages(16 * sizeof(struct proc_info), 2);
-  for (struct proc_info *i = FILE_HANDLES, *l = FILE_HANDLES + 65536; i < l; ++i)
+  for (struct proc_info *i = PROCS, *l = PROCS + 65536; i < l; ++i)
     i->memory_start = 0;
 
   uint16_t pages_free = 0, pages_total = 0;

src/kernel/mem.c

@@ -36,6 +36,6 @@ void *allocate_pages(uint16_t n_pages, uint16_t proc_n) {
 }
 
 void deallocate_pages(void *from, uint16_t n_pages) {
-  for (uint16_t *mb = MMAP + ((uint32_t)from / 0x1000), *l = mb + n_pages; mb < l; ++mb)
+  for (uint16_t *mb = MMAP + (uint32_t)from / 0x1000, *l = mb + n_pages; mb < l; ++mb)
     *mb = 0;
 }

src/kernel/misc.h

@@ -22,6 +22,6 @@ OF THIS SOFTWARE.
 #ifndef MISC_H
 #define MISC_H
 
-void print_32(uint32_t n);
+void put_16(uint16_t n);
 
 #endif

src/kernel/proc.c

@@ -25,7 +25,7 @@ uint16_t new_proc(uint8_t *file) {
   uint16_t handle = open_file(file);
   if (handle)
     for (uint16_t id = 3; id; ++id)
-      if (!(PROCS[id].memory_start)) {
+      if (!PROCS[id].memory_start) {
         uint32_t size = get_size(id);
         void *mem = PROCS[id].memory_start = allocate_pages(PROCS[id].n_pages = (size - 1) / 4096 + 1, id);
         read_file(handle, size, mem);