Load wallpaper from disk

.gitignore

@@ -1 +1,2 @@
 *.bin
+*.img

Makefile

@@ -1,20 +1,28 @@
 NASM = nasm
+PYTHON = python3
 
 .SUFFIXES:
-.SUFFIXES: .bin .asm
+.SUFFIXES: .bin .asm .ansi
 
-all: ponydos.bin
+all: ponydos.img
 
-run: ponydos.bin
-	qemu-system-i386 -fda ponydos.bin
+ponydos.img: ponydos.bin wallpaper.bin
+	rw -i /dev/zero -o $@ -c 1440K
+	rw -i ponydos.bin -o $@
+	rw -i wallpaper.bin -o $@ -O 512
 
 .asm.bin:
 	$(NASM) -fbin -o $@ $<
 
+.ansi.bin:
+	$(PYTHON) process_wallpaper.py $< $@ 7 0 0 0
+
+run: ponydos.img
+	qemu-system-i386 -fda $<
+
 clean:
-	rm -f *.bin
+	rm -f *.bin *.img
 
 distclean: clean
-	qemu-system
 
 .PHONY: all run clean distclean

ponydos.asm

@@ -6,6 +6,8 @@ org 0x7c00
 COLUMNS equ 80
 ROWS equ 25
 
+WALLPAPER equ 0x500
+
 jmp 0:start
 start:
 	cld
@@ -27,6 +29,8 @@ start:
 	xor al, al
 	rep stosb
 
+	mov [boot_disk], dl
+
 initialize_mouse:
 	; Initialize mouse
 	; https://www.ctyme.com/intr/rb-1601.htm
@@ -60,21 +64,26 @@ initialize_mouse:
 
 	.done:
 
-initialize_screen:
-	mov ax, 0xb800 ; VGA text video memory
-	mov es, ax
-
+load_wallpaper:
 	; Clear screen with asterisks and 15-0 background-foreground
 	mov ax, 0xf000 + '*'
 	mov cx, 25*80
-	xor di, di
+	mov di, WALLPAPER
 	rep stosw
 
+	mov ax, 1
+	mov bl, [boot_disk]
+	mov cx, 8
+	mov di, WALLPAPER
+	call read_sectors
+
+initialize_screen:
 	; Disable text cursor
 	mov ah, 0x01
 	mov ch, 0x20
 	int 0x10
 
+	call draw_wallpaper
 	call flip_mouse_cursor
 
 mainloop:
@@ -98,6 +107,30 @@ mainloop:
 		call flip_mouse_cursor
 		jmp mainloop
 
+; ------------------------------------------------------------------
+; Drawing subroutines
+; ------------------------------------------------------------------
+
+draw_wallpaper:
+	push ax
+	push bx
+	push cx
+	push es
+
+	mov bx, 0xb800
+	mov es, bx
+
+	mov si, WALLPAPER
+	xor di, di
+	mov cx, 80*25
+	rep movsw
+
+	pop es
+	pop cx
+	pop bx
+	pop ax
+	ret
+
 flip_mouse_cursor:
 	push ax
 	push bx
@@ -131,6 +164,75 @@ flip_mouse_cursor:
 	pop ax
 	ret
 
+; ------------------------------------------------------------------
+; Disk subroutines
+; ------------------------------------------------------------------
+
+; in:
+;  ax = LBA of first sector
+;  bl = drive number
+;  cx = number of sectors to read (must be at least 1)
+;  es:di = output buffer
+read_sectors:
+	push ax
+	push cx
+	push di
+
+	.loop:
+		call read_sector
+		inc ax
+		add di, 512
+		loop .loop
+
+	pop di
+	pop cx
+	pop ax
+	ret
+
+; in:
+;  ax = LBA of first sector
+;  bl = drive number
+;  es:di = output buffer
+read_sector:
+	push ax
+	push bx
+	push cx
+	push dx
+
+	mov cx, 18
+	div cx
+
+	; cl = sector (1…18)
+	mov cl, dl
+	inc cl
+
+	; dh = head (0…1)
+	mov dh, 1
+	and dh, al
+
+	; ch = cylinder
+	shr ax, 1
+	mov ch, al
+
+	; dl = drive number
+	mov dl, bl
+
+	; es:bx = output buffer
+	mov bx, di
+
+	mov ax, 0x0201 ; read one sector
+	int 0x13
+
+	pop dx
+	pop cx
+	pop bx
+	pop ax
+	ret
+
+; ------------------------------------------------------------------
+; Mouse callback
+; ------------------------------------------------------------------
+
 Y_OVERFLOW equ 0x80
 X_OVERFLOW equ 0x40
 Y_NEGATIVE equ 0x20
@@ -205,6 +307,10 @@ mouse_handler:
 	pop ax
 	retf
 
+; ------------------------------------------------------------------
+; Debug routines
+; ------------------------------------------------------------------
+
 hexprint16:
 	xchg ah, al
 	call hexprint8
@@ -234,10 +340,22 @@ hexprint4:
 	pop ax
 	ret
 
+hang:
+	hlt
+	jmp hang
+
+; ------------------------------------------------------------------
+; Padding and boot sector signature
+; ------------------------------------------------------------------
+
 times 510-($-$$) db 0
 db 0x55
 db 0xaa
 
+; ------------------------------------------------------------------
+; Zero-initialized variables
+; ------------------------------------------------------------------
+
 section .bss
 _bss_start:
 
@@ -248,4 +366,6 @@ mouse_buttons resb 1
 mouse_column resb 1
 mouse_row resw 1
 
+boot_disk resb 1
+
 _bss_end:

process_wallpaper.py

@@ -0,0 +1,82 @@
+import sys
+
+WIDTH = 80
+HEIGHT = 25
+# ANSI orders the colours black, red, green, yellow, blue, magenta, cyan, white
+# VGA orders them black, blue, green, cyan, red, magenta, yellow, white
+color_map = [0, 4, 2, 6, 1, 5, 3, 7]
+
+if len(sys.argv) != 7:
+	print("Usage: {sys.argv[0]} infile outfile default_fgcolor default_bgcolor origin_x origin_y", file=sys.stderr)
+	sys.exit(1)
+
+infile = sys.argv[1]
+outfile = sys.argv[2]
+
+default_fgcolor = int(sys.argv[3])
+assert 0 <= default_fgcolor <= 15
+default_bgcolor = int(sys.argv[4])
+assert 0 <= default_bgcolor <= 15
+
+origin_x = int(sys.argv[5])
+assert 0 <= origin_x < WIDTH
+origin_y = int(sys.argv[6])
+assert 0 <= origin_y < HEIGHT
+
+chars = [bytearray([0]*HEIGHT) for _ in range(WIDTH)]
+attributes = [[(default_fgcolor, default_bgcolor)]*HEIGHT for _ in range(WIDTH)]
+
+with open(infile, 'rb') as f:
+	ansitext = f.read()
+
+x = origin_x
+y = origin_y
+fgcolor = default_fgcolor
+bgcolor = default_bgcolor
+
+line = 1
+line_start = 0
+index = 0
+while index < len(ansitext):
+	if ansitext[index:].startswith(b'\x1b['):
+		index += len(b'\x1b[')
+		escape_length = ansitext[index:].index(b'm')
+		escape = ansitext[index:index+escape_length]
+		for color_parameter in escape.split(b';'):
+			color_parameter = int(color_parameter)
+			if color_parameter == 39:
+				fgcolor = default_fgcolor
+			elif color_parameter == 49:
+				bgcolor = default_bgcolor
+			elif 30 <= color_parameter <= 37:
+				fgcolor = color_map[color_parameter - 30]
+			elif 40 <= color_parameter <= 47:
+				bgcolor = color_map[color_parameter - 40]
+			elif 90 <= color_parameter <= 97:
+				fgcolor = color_map[color_parameter - 90] + 8
+			elif 100 <= color_parameter <= 107:
+				bgcolor = color_map[color_parameter - 100] + 8
+			else:
+				print(f'{line},{index-line_start+1}: Unknown colour escape {color_parameter}')
+		index += escape_length + len(b'm')
+	elif ansitext[index] == 13:
+		x = origin_x
+		index += 1
+	elif ansitext[index] == 10:
+		x = origin_x
+		y += 1
+		index += 1
+		line += 1
+		line_start = index
+	else:
+		chars[x][y] = ansitext[index]
+		attributes[x][y] = (fgcolor, bgcolor)
+		index += 1
+		x += 1
+
+with open(outfile, 'wb') as f:
+	for y in range(HEIGHT):
+		for x in range(WIDTH):
+			fgcolor, bgcolor = attributes[x][y]
+			char = chars[x][y]
+			f.write(bytes([char, (bgcolor<<4) | fgcolor]))

wallpaper.ansi

@@ -0,0 +1,25 @@
+ANSI art is my
+passion
+line 3
+line 4
+line 5
+line 6
+line 7
+line 8
+line 9
+line 10
+line 11
+line 12
+line 13
+line 14
+line 15
+line 16
+line 17
+line 18
+line 19
+line 20
+line 21
+line 22
+line 23
+line 24
+line 25