Move the system from after the bootloader to the beginning of usable memory and the bootloader and system stacks to after their respective programs, fix a couple of bugs in the bootloader that made it not load the system correctly above a specific size, abandon the goal of eventual subdirectory support and modify the project directory structure and make.sh accordingly, and start writing fileify.

SOURCE/HELP.INC

@@ -1,10 +0,0 @@
-;Prints help.
-
-help:
-
-mov si, .help
-call println
-
-ret
-
-.help db "Input:", 0xd, 0xa, "* Typing a character overwrites the cursor location.", 0xd, 0xa, "* The erase (=tab) key erases the cursor location.", 0xd, 0xa, "* The space and backspace keys move the cursor.", 0xd, 0xa, "Commands:", 0xd, 0xa, "* echo: echoes its input.", 0xd, 0xa, "* hello: a hello world program.", 0xd, 0xa, "* help: you are reading it.", 0xd, 0xa, "* keycode: echoes the BIOS code of a key.", 0x0

make.sh

@@ -1,18 +1,22 @@
 #!/bin/bash
 
-cd SOURCE/
-
-if [ "$1" == "-F1440" ]
-    then nasm BOOT.ASM -d F1440 -f bin -o ../BOOT.BIN
-    else nasm BOOT.ASM -f bin -o ../BOOT.BIN
+rm -f EttinOS.img
+if [[ ! -d "bin" ]]
+then
+    mkdir bin
 fi
-nasm SYSTEM.ASM -f bin -o ../SYSTEM.BIN
+
+cd src/
+if [ "$1" == "-F1440" ]
+    then nasm BOOT.ASM -d F1440 -f bin -o ../bin/BOOT.BIN
+    else nasm BOOT.ASM -f bin -o ../bin/BOOT.BIN
+fi
+nasm SYSTEM.ASM -f bin -o ../bin/SYSTEM.BIN
 
 cd ..
-rm -f EttinOS.img
-if [ "$1" == "-F1440" ]
+if [ "$1" == "-1440" ]
     then mkfs.fat -C EttinOS.img 1440
     else mkfs.fat -C EttinOS.img 360
 fi
-dd if=BOOT.BIN of=EttinOS.img conv=notrunc bs=512 count=1
-mcopy -i EttinOS.img SYSTEM.BIN ::
+dd if=bin/BOOT.BIN of=EttinOS.img conv=notrunc bs=512 count=1
+mcopy -i EttinOS.img bin/SYSTEM.BIN ::

src/BOOT.ASM

@@ -7,7 +7,7 @@ nop
 ;Disk description tables
 
 %ifdef F1440
-;1.44 MB 3.5" floppy disk (enable by passing -d F1440 to NASM)
+;1.44 MB 3.5" floppy disk (enable with the argument -d F1440 when building)
 oemlabel        db "ETTINOS "
 sectorsize      dw 0x200 ;bytes
 clustersize     db 0x1 ;sectors
@@ -52,17 +52,17 @@ filesystem      db "FAT12   "
 
 start:
 
-;Set up the data segment
+;Setup
+;Set up the data, stack, and extra segments
 mov ax, 0x0
 mov ds, ax
-
+mov ss, ax
+mov es, ax
 ;Set up the stack
 cli
-mov ax, 0x0
-mov ss, ax
-mov sp, 0x7c00
+mov sp, stack
+add sp, 0x100
 sti
-
 ;Store the boot device number
 mov [bootdev], dl
 
@@ -75,9 +75,7 @@ add ax, [bootsectors]
 push ax
 call calcsource
 ;Set the destination
-mov si, 0x7e00
-mov bx, ds
-mov es, bx
+mov si, 0x7f00
 mov bx, si
 ;Set the size
 push dx
@@ -93,10 +91,8 @@ mov ah, 0x2
 int 0x13
 
 ;Search the root for the system
-;Set DI to the root FAT
-mov ax, ds
-mov es, ax
-mov di, 0x7e00
+;Set DI to the root
+mov di, 0x7f00
 ;Initialise the search loop
 mov cx, word [rootentries]
 mov ax, 0x0
@@ -110,13 +106,13 @@ rep cmpsb
 je loadfat
 ;Set DI to the next entry
 add ax, 0x20
-mov di, 0x7e00
+mov di, 0x7f00
 add di, ax
 ;Load CX from the stack
 pop cx
 loop search
 
-;Load the system FAT
+;Load the system entry
 loadfat:
 ;Load CX from the stack
 pop cx
@@ -127,7 +123,7 @@ mov word [cluster], ax
 mov ax, 0x1
 call calcsource
 ;Set the destination
-mov di, 0x7e00
+mov di, 0x7f00
 mov bx, di
 ;Set the size
 mov ax, [sectorsperfat]
@@ -140,20 +136,21 @@ int 0x13
 ;Load a cluster
 loadcluster:
 ;Set the source
+pop cx
 pop bx
-pop ax
-push ax
-push bx
-add ax, bx
+mov ax, word [cluster]
 sub ax, 0x2
-add ax, word [cluster]
+mul byte [clustersize]
+add ax, bx
+add ax, cx
+push bx
+push cx
 call calcsource
 ;Set the destination
-mov ax, 0x0
-mov es, ax
 mov bx, word [pointer]
 ;Set the size
-mov al, 0x1
+;mov al, 0x1
+mov al, [clustersize]
 ;Load
 mov ah, 0x2
 int 0x13
@@ -165,7 +162,7 @@ mov bx, 0x3
 mul bx
 mov bx, 0x2
 div bx
-mov si, 0x7e00
+mov si, 0x7f00
 add si, ax
 mov ax, word [ds:si]
 or dx, dx
@@ -182,19 +179,22 @@ contcalc:
 mov word [cluster], ax
 cmp ax, 0xff8
 jge boot
-add word [pointer], 0x200
+mov ax, [sectorsize]
+mul word [clustersize]
+add word [pointer], ax
 jmp loadcluster
 
+;Boot the system
 boot:
-jmp 0x0:0x9e00
-
-sysfile db "SYSTEM  BIN"
+jmp 0x0:0x500
 
+;Data
 bootdev db 0x0
-
+sysfile db "SYSTEM  BIN"
 cluster dw 0x0
-pointer dw 0x9e00
+pointer dw 0x500
 
+;Calculate the source arguments for loading data from the disk
 calcsource:
 push ax
 push bx
@@ -215,8 +215,10 @@ pop ax
 mov dl, byte [bootdev]
 ret
 
+;Pad the binary to a full sector and make the disk bootable
 ;Padding
 times 0x1fe-($-$$) db 0x0
-
 ;Boot signature
 dw 0xaa55
+
+stack:

src/FILEIFY.INC

@@ -0,0 +1,120 @@
+;Reads a string, checks if it is a valid 8.3 file name, converts it into FAT formatting, and prints it.
+
+;To do: change the .test call to work with flags instead of direct jumps.
+
+fileify:
+
+;Read a string
+mov di, buffer
+mov al, 0xff
+call readln
+
+;Set SI and DI
+mov si, buffer
+mov di, .file
+
+;Initialise the name with spaces
+mov cx, 0xb
+mov al, 0x20
+rep stosb
+sub di, 0xb
+
+;Initialise the length counter for the main part of the name
+mov bl, 0x8
+
+.nameloop:
+
+;Load a character
+lodsb
+
+;Check for a period
+cmp al, 0x2e
+je .initext
+
+call .test
+jmp .nameloop
+
+.initext:
+;Set DI and initialise the counter for the extension
+mov bl, 0x3
+mov di, .file+0x8
+
+.extloop:
+call .test
+jmp .extloop
+
+.error:
+mov si, .errormsg
+call println
+jmp .done
+
+.print:
+mov si, .name
+call printstr
+mov si, .extension
+call printstr
+mov al, 0x7c
+call printch
+call printnl
+
+.done:
+ret
+
+.file times 0xc db 0x0
+
+.errormsg db "Invalid file name", 0x0
+
+.test:
+
+;Check for the string end
+cmp al, 0x0
+je .print
+
+;Check for the length limit
+cmp bl, 0x0
+je .error
+
+;Check for invalid characters
+cmp al, 0x22
+je .error
+cmp al, 0x2a
+jl .contcheck1
+cmp al, 0x2c
+jg .contcheck1
+jmp .error
+.contcheck1:
+cmp al, 0x2f
+je .error
+cmp al, 0x3a
+jl .contcheck2
+cmp al, 0x3f
+jg .contcheck2
+jmp .error
+.contcheck2:
+cmp al, 0x5b
+jl .contcheck3
+cmp al, 0x5d
+jg .contcheck3
+jmp .error
+.contcheck3:
+cmp al, 0x7c
+je .error
+
+;Find and convert lower case letters to upper case
+;Check for lower case
+cmp al, 0x61
+jl .conttest
+cmp al, 0x7a
+jg .conttest
+;Convert lower to upper case
+sub al, 0x20
+
+.conttest:
+
+;Store the character
+stosb
+
+;Increase the counter
+dec bl
+
+ret

src/HELP.INC

@@ -0,0 +1,10 @@
+;Prints help.
+
+help:
+
+mov si, .help
+call println
+
+ret
+
+.help db "Input:", 0xd, 0xa, "  * Typing a character overwrites the cursor location.", 0xd, 0xa, "  * The erase (=tab) key erases the cursor location.", 0xd, 0xa, "  * The space and backspace keys move the cursor.", 0xd, 0xa, "Commands:", 0xd, 0xa, "  * echo: echoes its input.", 0xd, 0xa, "  * fileify: prints its input in FAT format if it is a valid filename.", 0xd, 0xa, "  * hello: a hello world program.", 0xd, 0xa, "  * help: you are reading it.", 0xd, 0xa, "  * keycode: echoes the BIOS code of a key.", 0x0

src/SYSTEM.ASM

@@ -1,5 +1,5 @@
 CPU 8086
-ORG 0x9e00
+ORG 0x500
 
 jmp start
 
@@ -16,12 +16,19 @@ jmp start
 
 ;Commands
 %include "ECHO.INC"
+;%include "FILEIFY.INC"
 %include "HELLO.INC"
 %include "HELP.INC"
 %include "KEYCODE.INC"
 
 start:
 
+;Set up the stack
+cli
+mov sp, stack
+add sp, 0x100
+sti
+
 ;Get the terminal width
 mov ah, 0xf
 int 0x10
@@ -33,10 +40,10 @@ call println
 
 loop:
 
+;Prompt for and read a command
 ;Print a prompt
 mov si, prompt
 call printstr
-
 ;Read a command
 mov di, buffer
 mov al, 0xff
@@ -52,10 +59,20 @@ je loop
 mov si, buffer
 mov di, cmd.echo
 call cmpstr
+;jnc .fileify
 jnc .hello
 ;Execute
 call echo
 jmp loop
+;.fileify:
+;;Check
+;mov si, buffer
+;mov di, cmd.fileify
+;call cmpstr
+;jnc .hello
+;;Execute
+;call fileify
+;jmp loop
 .hello:
 ;Check
 mov si, buffer
@@ -96,10 +113,13 @@ prompt db "> ", 0x0
 
 cmd:
 .echo    db "echo", 0x0
+.fileify  db "fileify", 0x0
 .hello   db "hello", 0x0
 .help    db "help", 0x0
 .keycode db "keycode", 0x0
 
 error db "Unknown command", 0x0
 
-buffer times 0xff db 0
+buffer times 0xff db 0x0
+
+stack: