Implement initial builtin commands

7 files changed, 302 insertions, 17 deletions

diff --git a/builtin_clear.asm b/builtin_clear.asm
new file mode 100644
index 0000000..cac6216
--- /dev/null
+++ b/builtin_clear.asm
@@ -0,0 +1,11 @@
+%ifndef _BUILTIN_CLEAR_ASM
+%define _BUILTIN_CLEAR_ASM
+
+builtin_clear:
+	call cls		; clear console
+	push 0000h		; home position 0x0
+	call setcursor		; home cursor on console
+	add sp, 2		; cleanup stack
+	ret
+
+%endif
diff --git a/builtin_echo.asm b/builtin_echo.asm
index 1b4af89..9cc1e9c 100644
--- a/builtin_echo.asm
+++ b/builtin_echo.asm
@@ -5,16 +5,25 @@ builtin_echo:
 	push bp
 	mov bp, sp
 
-	mov bx, word [bp + 4]
-	add bx, 2
-	push word [bx]
-	push .msg_fmt
-	call printf
-	add sp, 2 * 2
+	mov cx, word [bp + 4]	; argc
+	mov bx, word [bp + 6]	; argv
 
-	mov sp, bp
-	pop bp
-	ret
-	.msg_fmt db '%s\n', 0
+	cmp cx, 0		; if no arguments, return
+	jbe .return
+
+	.output:		; print argv
+		push word [bx]
+		push .msg_fmt
+		call printf
+		add sp, 2 * 2
+		add bx, 2
+		dec cx
+		jne .output
+
+	.return:
+		mov sp, bp
+		pop bp
+		ret
+	.msg_fmt db '%s ', 0
 
 %endif
diff --git a/builtin_exit.asm b/builtin_exit.asm
index 74594e1..08b0e38 100644
--- a/builtin_exit.asm
+++ b/builtin_exit.asm
@@ -2,16 +2,13 @@
 %define _BUILTIN_EXIT_ASM
 
 builtin_exit:
-	push bp
-	mov bp, sp
-
 	push .msg_fmt
 	call printf
 	add sp, 2 * 1
 
-	add sp, 2	; cleanup previous call address
+	mov [terminal_exit], byte 1
 
-	jmp terminal
+	ret
 	.msg_fmt db 'exiting...\n', 0
 
 %endif
diff --git a/builtin_free.asm b/builtin_free.asm
new file mode 100644
index 0000000..96e3c86
--- /dev/null
+++ b/builtin_free.asm
@@ -0,0 +1,35 @@
+%ifndef _BUILTIN_FREE_ASM
+%define _BUILTIN_FREE_ASM
+
+builtin_free:
+	push bp
+	mov bp, sp
+
+	mov cx, word [bp + 4]	; argc
+	mov bx, word [bp + 6]	; argv
+
+	;cmp cx, 0		; if no arguments, return
+	;jbe .return
+
+	mov ah, 88h		; get extended memory size
+	int 15h
+	mov dx, ax
+
+	int 12h			; get conventional memory size
+				; but it's pretty much bogus
+
+	push dx
+	push ax
+	push .msg_fmt
+	call printf
+	add sp, 2 * 2
+	add bx, 2
+
+	.return:
+		mov sp, bp
+		pop bp
+		ret
+	.msg_fmt db 'Conventional memory: %dK\n'
+		 db 'Extended memory: %dK', 0
+
+%endif
diff --git a/builtin_vga_demo.asm b/builtin_vga_demo.asm
new file mode 100644
index 0000000..54d4a4f
--- /dev/null
+++ b/builtin_vga_demo.asm
@@ -0,0 +1,123 @@
+%ifndef _VGA_DEMO_ASM
+%define _VGA_DEMO_ASM
+
+VGA_SCREEN_WIDTH equ 320
+VGA_SCREEN_HEIGHT equ 200
+VGA_COLORS equ 0x100
+
+vga_plot:
+	%define .x [bp + 4]
+	%define .y [bp + 6]
+	%define .color [bp + 8]
+	push bp
+	mov bp, sp
+	pusha
+	push es
+	push ds
+	;push ax
+	;push cx
+	;push dx
+	;push di
+;
+	xor ax, ax
+	xor cx, cx
+	xor dx, dx
+	xor di, di
+
+	mov ax, 0A000h
+	mov es, ax			; Store VGA memory segment in ES
+	mov ds, ax
+
+	mov ax, word VGA_SCREEN_WIDTH
+	mov cx, word .y
+	mul cx
+	add ax, word .x
+	mov di, ax
+
+	mov ax, word .color
+	mov [es:di], ax
+
+	.return:
+		;pop di
+		;pop dx
+		;pop cx
+		;pop ax
+		pop ds
+		pop es
+		popa
+		mov sp, bp
+		pop bp
+		ret
+
+
+
+builtin_vga_demo:
+	push bp
+	mov bp, sp
+	sub sp, 2
+
+	;
+	; no arguments for this program
+	;
+
+	.main:
+		mov ah, 0fh		; get current video mode
+		int 10h
+		mov [bp - 2], al	; save current video mode
+
+		mov ah, 00h
+		mov al, 13h		; set 256 color VGA mode
+		int 10h
+
+		mov di, 0ffh
+		.loop:
+			mov si, .data_smiley	; address of smiley face array
+			mov cx, 10	; number of array elements
+		.do_plot:
+			mov ax, [si]	; Load coordinates
+			add si, 2	; Next set
+
+			movzx dx, al	; Store y
+			movzx bx, ah	; Store x
+
+			push di		; color
+			push dx		; y
+			push bx		; x
+			call vga_plot	; write pixel
+			add sp, 2 * 3
+
+			and di, 0ffh	; DI overflows into infinity so
+					; use its low byte instead of resetting to zero
+			dec di		; Next color
+			dec cx		; Next loop
+			jne .do_plot
+
+		xor ax, ax
+		call kbd_read_async	; ZF=1 if no key is pressed
+		je .loop
+
+	.return:
+		mov ah, 00h		; Set video mode
+		mov al, [bp - 2]	; Restore video mode
+		int 10h
+
+		add sp, 2
+		mov sp, bp
+		pop bp
+		ret
+
+	.data_smiley:
+		;  plots a smiley face using coordinates
+		;  row col
+		db 01h,01h	; left eye
+		db 01h,05h	; right eye
+		db 04h,03h	; nose
+		db 06h,00h	; left uptick mouth
+		db 06h,06h	; mouth
+		db 07h,01h	; mouth
+		db 07h,02h	; mouth
+		db 07h,03h	; mouth
+		db 07h,04h	; mouth
+		db 07h,05h	; right uptick mouth
+
+%endif
diff --git a/builtin_video_mode.asm b/builtin_video_mode.asm
new file mode 100644
index 0000000..571899e
--- /dev/null
+++ b/builtin_video_mode.asm
@@ -0,0 +1,98 @@
+%ifndef _BUILTIN_VIDEO_MODE_ASM
+%define _BUILTIN_VIDEO_MODE_ASM
+
+builtin_video_mode:
+	push bp
+	mov bp, sp
+
+	mov cx, [bp + 4]	; Load argc
+	mov bx, [bp + 6]	; Load argv
+
+	cmp cx, 1		; Not enough args?
+	jl .no_args		; ... die
+	jmp .main
+
+	.no_args:
+		push .error_arg
+		call printf
+		add sp, 2 * 1
+		jmp .return
+
+	; main program
+
+	.main:
+		mov bx, [bx]	; Load first element in argv array
+		mov si, bx	; First element is source index
+
+		push bx		; Get length of element
+		call strlen
+		add sp, 2
+		mov cx, ax	; Store length
+		mov bx, 0
+
+
+		mov ax, 0
+		mov dx, 0
+		.chars:
+			lodsb		; Load character from ES:SI
+			cmp ax, '9'	; If value is greater than '9' it's likely hex, so
+					; adjust AX to compensate
+			jg .ishex
+
+			sub ax, '0'	; Otherwise, the value is base-10
+			jmp .nosub
+
+		.tolower:
+			sub ax, 20h
+		.ishex:
+			cmp ax, 'a'
+			jge .tolower	; If we recieved a lowercase letter, convert it
+					; to uppercase, then continue
+
+			cmp ax, 'F'	; Is this a valid hexadecimal value? (0 ~ F)
+			jg .invalid_input
+
+			sub ax, 'A'	; Convert character to BCD
+			add ax, 10
+
+		.nosub:
+			shl dx, 4	; Shift current BCD value 4-bits left
+			or dx, ax	; Tack on the latest value
+			dec cx		; Decrement counter
+			jne .chars	; continue until no characters remain
+
+
+		cmp dx, 13h		; Is the final value a valid video mode?
+		jg .invalid_mode
+
+
+		mov al, dl		; BIOS video services only operate on a byte value
+					; ... oh well.
+
+		mov ah, 00h
+		int 10h			; Set video mode
+
+	.return:
+		mov sp, bp
+		pop bp
+		ret
+
+	.invalid_input:
+		push ax
+		push .error_hex
+		call printf
+		add sp, 2 * 2
+		jmp .return
+
+	.invalid_mode:
+		push dx
+		push .error_mode
+		call printf
+		add sp, 2 * 2
+		jmp .return
+
+	.error_arg: db 'error: no graphics mode requested. (0..13)\n', 0
+	.error_hex: db 'error: "%c" is an invalid hexadecimal value (0..F)\n', 0
+	.error_mode: db 'error: %2x is an invalid video mode (0..13)\n', 0
+
+%endif
diff --git a/builtins.asm b/builtins.asm
index 268e4b2..d09282c 100644
--- a/builtins.asm
+++ b/builtins.asm
@@ -1,19 +1,31 @@
 %ifndef _BUILTINS_ASM
 %define _BUILTINS_ASM
 
-%include "builtin_reboot.asm"
-%include "builtin_exit.asm"
+%include "builtin_clear.asm"
 %include "builtin_echo.asm"
+%include "builtin_exit.asm"
+%include "builtin_free.asm"
+%include "builtin_reboot.asm"
+%include "builtin_vga_demo.asm"
+%include "builtin_video_mode.asm"
 
 t_builtins_fn:
+	dw builtin_clear
 	dw builtin_echo
 	dw builtin_exit
+	dw builtin_free
 	dw builtin_reboot
+	dw builtin_vga_demo
+	dw builtin_video_mode
 	dw 0
 
 t_builtins_str:
+	.clear: db 'clear', 0
 	.echo: db 'echo', 0
 	.exit: db 'exit', 0
+	.free: db 'free', 0
 	.reboot: db 'reboot', 0
+	.vga_demo: db 'vga_demo', 0
+	.video_mode: db 'video_mode', 0
 	dw 0
 %endif