Line prefixes for listings

edlin.asm

@@ -49,6 +49,18 @@ int_ctrl_break equ 0x23
 %macro addw 2
 	db 0x03, 0xc0 + 8 * %1 + %2
 %endmacro
+%macro adcb 2
+	db 0x12, 0xc0 + 8 * %1 + %2
+%endmacro
+%macro cmpw 2
+	db 0x3b, 0xc0 + 8 * %1 + %2
+%endmacro
+%macro movw 2
+	db 0x8b, 0xc0 + 8 * %1 + %2
+%endmacro
+%macro movb 2
+	db 0x8a, 0xc0 + 8 * %1 + %2
+%endmacro
 %macro orw 2
 	db 0x0b, 0xc0 + 8 * %1 + %2
 %endmacro
@@ -58,15 +70,12 @@ int_ctrl_break equ 0x23
 %macro subw 2
 	db 0x2b, 0xc0 + 8 * %1 + %2
 %endmacro
+%macro subb 2
+	db 0x2a, 0xc0 + 8 * %1 + %2
+%endmacro
 %macro xorw 2
 	db 0x33, 0xc0 + 8 * %1 + %2
 %endmacro
-%macro cmpw 2
-	db 0x3b, 0xc0 + 8 * %1 + %2
-%endmacro
-%macro movw 2
-	db 0x8b, 0xc0 + 8 * %1 + %2
-%endmacro
 
 ; Sign extended byte to byte
 %macro cmpb_addr_ext 2
@@ -561,49 +570,79 @@ db 0x42 ; 04AC inc dx
 db 0x3B, 0xDA ; 04AD cmp bx,dx
 db 0x75, 0xF7 ; 04AF jnz 0x4a8
 db 0xC3 ; 04B1 ret
-db 0x53 ; 04B2 push bx
-db 0xB0, 0x20 ; 04B3 mov al,0x20
-db 0xE8, 0x6C, 0x04 ; 04B5 call 0x924
-db 0xE8, 0x13, 0x00 ; 04B8 call 0x4ce
-db 0xB0, 0x3A ; 04BB mov al,0x3a
-db 0xE8, 0x64, 0x04 ; 04BD call 0x924
-db 0xB0, 0x2A ; 04C0 mov al,0x2a
-db 0x5B ; 04C2 pop bx
-db 0x3B, 0x1E, 0x90, 0x0A ; 04C3 cmp bx,[0xa90]
-db 0x74, 0x02 ; 04C7 jz 0x4cb
-db 0xB0, 0x20 ; 04C9 mov al,0x20
-db 0xE9, 0x56, 0x04 ; 04CB jmp 0x924
-db 0x33, 0xC0 ; 04CE xor ax,ax
-db 0x8A, 0xD0 ; 04D0 mov dl,al
-db 0xB9, 0x10, 0x00 ; 04D2 mov cx,0x10
-db 0xD1, 0xE3 ; 04D5 shl bx,1
-db 0x12, 0xC0 ; 04D7 adc al,al
-db 0x27 ; 04D9 daa
-db 0x86, 0xC4 ; 04DA xchg al,ah
-db 0x12, 0xC0 ; 04DC adc al,al
-db 0x27 ; 04DE daa
-db 0x86, 0xC4 ; 04DF xchg al,ah
-db 0x12, 0xD2 ; 04E1 adc dl,dl
-db 0xE2, 0xF0 ; 04E3 loop 0x4d5
-db 0xB3, 0x10 ; 04E5 mov bl,0x10
-db 0x92 ; 04E7 xchg ax,dx
-db 0xE8, 0x16, 0x00 ; 04E8 call 0x501
-db 0x8A, 0xC6 ; 04EB mov al,dh
-db 0xE8, 0x02, 0x00 ; 04ED call 0x4f2
-db 0x8A, 0xC2 ; 04F0 mov al,dl
-db 0x8A, 0xF0 ; 04F2 mov dh,al
-db 0xD0, 0xE8 ; 04F4 shr al,1
-db 0xD0, 0xE8 ; 04F6 shr al,1
-db 0xD0, 0xE8 ; 04F8 shr al,1
-db 0xD0, 0xE8 ; 04FA shr al,1
-db 0xE8, 0x02, 0x00 ; 04FC call 0x501
-db 0x8A, 0xC6 ; 04FF mov al,dh
-db 0x24, 0x0F ; 0501 and al,0xf
-db 0x74, 0x02 ; 0503 jz 0x507
-db 0xB3, 0x00 ; 0505 mov bl,0x0
-db 0x04, 0x30 ; 0507 add al,0x30
-db 0x2A, 0xC3 ; 0509 sub al,bl
-db 0xE9, 0x16, 0x04 ; 050B jmp 0x924
+
+print_line_prefix: ; 04b2
+	push bx
+
+	mov al, ' '
+	call print_char
+	call print_number
+	mov al, ':'
+	call print_char
+	mov al, '*'
+
+	pop bx
+
+	cmp bx, [current_line]
+	je .end
+	mov al, ' '
+
+	.end: jmp print_char
+
+print_number: ; 04ce
+	; Input in bx
+
+	; Zero out the 5-digit BCD number
+	xorw r_ax, r_ax
+	movb r_dl, r_al
+
+	mov cx, 16
+	.loop: ; 04d5
+		shl bx, 1
+
+		; Double al (bcd), and add in carry out from the shift
+		adcb r_al, r_al
+		daa
+		; Double ah (bcd) and propagate carry
+		xchg al, ah
+		adcb r_al, r_al
+		daa
+		xchg al, ah
+		; Double dl (bcd) and propagate carry
+		adcb r_dl, r_dl
+
+		loop .loop
+
+print_bcd:
+	; Prints a 5-digit BCD number stored in DX:AX as such (x is ignored)
+	; dh dl ah al
+	; xx x1 23 45
+	mov bl, '0' - ' ' ; If value is zero, replace with space
+
+	xchg ax, dx
+	; First digit, low nybble of dl
+	call print_bcd_digit
+	; Next two digits, ah
+	movb r_al, r_dh
+	call print_bcd_byte
+	; Final two digits, al
+	movb r_al, r_dl
+
+print_bcd_byte: ; 04f2
+	movb r_dh, r_al
+	times 4 shr al, 1
+	call print_bcd_digit
+	movb r_al, r_dh
+
+print_bcd_digit: ; 0501
+	and al, 0xf
+	jz .to_ascii
+	mov bl, 0 ; Only apply replacement to zero values
+
+	.to_ascii:
+	add al, '0'
+	subb r_al, r_bl
+	jmp print_char
 
 command_l: ; 050e
 db 0x8B, 0x1E, 0x80, 0x0A ; 050E mov bx,[0xa80]