Work monitor program up to usable state

boot/monitor.asm

@@ -1,9 +1,10 @@
 ; monitor program that fits in a boot sector
 ; for debugging disk i/o and bootstrapping
 
-%define base (0x10000 - 0x400)
+%define base (0x10000 - 0x200)
 
 	org base
+	cpu 8086
 
 	; relocate to end of memory
 init:	; set up src addr
@@ -21,6 +22,9 @@ init:	; set up src addr
 	; set up stack
 	mov ss, ax
 	mov sp, di
+	; push defptr
+	push ds
+	push si
 	; relocate
 	mov cx, 0x100
 	rep movsw
@@ -32,32 +36,29 @@ init:	; set up src addr
 	mov byte [si], 0xCC
 	push cs
 	push si
+	sti
 	retf
 
 	; call here = run proc tail twice
 .l02:	call .l01
 .l01:	mov word [bx], entry
-	mov word [bx+2], es
+	mov word [bx+2], ss
 	add bx, 2*4
 	ret
 
-nl:	mov al, 0x0A
+nl:	mov ax, 0x0e0A
-	call putc
+	int 0x10
 	mov al, 0x0D
 	jmp putc
 
-	; print full register set
+space:	mov al, ' '
+putc:	mov ah, 0x0e
+	int 0x10
+	ret
+
+	; print register set
 printr: call nl
 	xor si, si
-.l01:	call .l02
-	add si, 2
-	cmp si, 18
-	jc .l01
-	mov si, 22
-	call .l02
-	les bx, [ss:bp+18]
-	jmp dump
-
 .l02:	mov ah, 0x0e
 	mov al, [cs:lbls+si]
 	int 0x10
@@ -65,24 +66,22 @@ printr: call nl
 	int 0x10
 	mov al, '='
 	int 0x10
-	mov dx, [ss:bp+si]
+	mov dx, [bp+si]
-	call printd
+	mov ch, ' '
-space:	mov al, ' '
+	call prints
-putc:	mov ah, 0x0e
+	add si, 2
-	int 0x10
+	cmp si, 24
-	ret
+	jc .l02
-
+	les bx, [bp+18]
-	; print far ptr ES:BX
+	jmp dump
-printf:	mov dx, es
-	call printd
-	mov al, ':'
-	call putc
-	mov dx, bx
-	call printd
-	jmp space
 
 	; print 16 bytes from ES:BX
-dump:	call printf
+dump:	mov dx, es
+	mov ch, ':'
+	call prints
+	mov dx, bx
+	mov ch, ' '
+	call prints
 	push bx
 	mov cx, 0x10
 .l01:	mov dh, [es:bx]
@@ -95,7 +94,7 @@ dump:	call printf
 	pop bx
 	ret
 
-printd:	call printb ; print dx
+printw:	call printb ; print dx
 printb:	call .l01 ; print dh
 .l01:	mov cl, 4
 	; grab highest nibble from dx
@@ -115,60 +114,78 @@ printn:	; map 0-9 to ascii codes for '0' to '9'
 	int 0x10
 	ret
 
+	; print dx and char ch
+prints:	call printw
+	mov al, ch
+	int 0x10
+	ret
+
 getc:	xor ax, ax
 	int 0x16
 	test al, al
 	jz getc
-	test al, 0x80
+	; to uppercase
-	jnz getc
 	cmp al, 0x60
 	jc .ret
 	sub al, 0x20
 .ret:	ret
 
-	; reads CX hex digits into DX
+inputw:	call inputb
-	; DX needs to be zero on entry
+inputb:	call inputn
-input:	call getc
+inputn:	jc .ret
+	call getc
 	cmp al, 0x20
-	je .err
+	stc
-	; must be above '0'
+	je .ret
 	sub al, 0x30
-	jc input
 	; if >9, turn 'A' to A
 	cmp al, 0x0A
 	jc .noadj
 	sub al, 7
 .noadj:	; must be smaller than 'F'
 	cmp al, 0x10
-	jnc input
+	jnc inputn
-	; append to DX
+	; append to dx
-	push cx
 	mov cl, 4
 	shl dx, cl
 	or dl, al
-	pop cx
 	; print, loop & clear exit
 	call printn
-	loop input
-	call space
 	clc
-	ret
+.ret:	ret
-.err:	call space
-	stc
-	ret
 
 	; edit word at ES:BX
 	; space exits with carry
 editw:	mov dx, [es:bx]
-	call printd
+	mov ch, '.'
-	mov al, '.'
+	call prints
-	call putc
+	clc
-	mov cx, 4
+	call inputw
-	call input
 	jc .err
 	mov [es:bx], dx
 .err:	ret
 
+cmd_o:	mov bx, di
+	jmp cmd_s.l01
+
+cmd_s:	lea bx, [di+2]
+.l01:	call editw
+	jmp cmd
+
+cmd_e:	les bx, [cs:di]
+	mov dh, [es:bx]
+	call printb
+	mov al, '.'
+	int 0x10
+	mov cx, 2
+	clc
+	call inputb
+	jc cmd
+	mov [es:bx], dl
+	inc word [cs:di]
+	call space
+	jmp cmd_e
+
 entry:	push es
 	push ds
 	push di
@@ -181,11 +198,7 @@ entry:	push es
 	mov bp, sp
 
 cmd_r:	call printr
-	; reset segment register
+cmd:	; display prompt
-cmd:	mov ax, cs
-	mov ds, ax
-	mov es, ax
-	; display prompt
 	call nl
 	mov al, '-'
 	call putc
@@ -197,14 +210,26 @@ cmd:	mov ax, cs
 	push ax
 	call space
 	pop ax
-	; branch out into commands
+	; set up default for cmds
-	les bx, [defptr]
+	mov dx, cs
+	mov ds, dx
+	mov es, dx
+	mov di, defptr
+	; show and edit mem
 	cmp al, 'D'
 	je cmd_d
-	cmp al, 'G'
+	cmp al, 'E'
-	je exit
+	je cmd_e
+	; show and edit regs
 	cmp al, 'R'
 	je cmd_r
+	cmp al, 'V'
+	je cmd_v
+	; actions
+	cmp al, 'G'
+	je cmd_g
+	cmp al, 'T'
+	je cmd_t
 	; set working ptr
 	cmp al, 'S'
 	je cmd_s
@@ -215,26 +240,39 @@ err:	mov al, '?'
 	call putc
 	jmp cmd
 
-cmd_d:	mov cx, 8
+cmd_d:	les bx, [di]
+	mov cx, 8
 .l01:	push cx
 	call nl
 	call dump
 	pop cx
 	add bx, 0x10
-	mov [defptr], bx
+	mov [cs:di], bx
 	loop .l01
 	jmp cmd
 
-cmd_o:	mov bx, defptr
+cmd_v:	call regn
-	jmp cmd_s.l01
+	mov ax, dx
-
+	mov di, lbls
-cmd_s:	mov bx, defptr+2
+	mov cx, 11
-.l01:	call editw
+	repne scasw
+	jne err
+	sub di, lbls+2
+	lea bx, [bp+di]
+	call space
+	call editw
 	jmp cmd
 
-hlt:	hlt
+regn:	call .l01
-	jmp hlt
+	xchg dh, dl
+.l01:	call getc
+	call putc
+	mov dh, al
+	ret
 
+cmd_t:	or byte [bp+23], 1
+	jmp exit
+cmd_g:	and byte [bp+23], 0xFE
 exit:	pop ax
 	pop cx
 	pop dx
@@ -251,11 +289,7 @@ lbls:	db "AXCXDXBXBPSIDI" ; gpr
 	db "DSES" ; seg regs
 	db "IPCSFL" ; iret frmae
 
-defptr:	dw 0x7C00, 0
+defptr:	equ (base-4)
 
 	times 510-($-$$) db 0x00
 	db 0x55,0xaa
-
-section .bss
-
-line:	resb 0x100