debug: Split commands into thematically organized files

debug/edit.asm

@@ -1,3 +1,61 @@
+; Commands and utils related to displaying or editing memory or registers
+
+cmd_r:	cmp byte [si], 0
+	je printregs
+	call eat_register
+	jc .err
+	mov al, [cs:bx+rnames]
+	call putc
+	mov al, [cs:bx+rnames+1]
+	call putc
+	call space
+	call edit_word
+	call crlf
+	ret
+.err:	mov di, eat_register.emsg
+	jmp parse_error
+
+printregs:
+	mov cx, 13
+	xor bx, bx
+	mov ah, 0x0e
+	mov si, reg_ax
+.loop:	push cx
+	mov dx, [cs:si+rnames]
+	lodsw
+	call printreg
+	pop cx
+	loop .loop
+
+	mov dx, [reg_fl]
+	mov si, fnames
+	mov cx, 16
+.floop:	mov al, [cs:si]
+	inc si
+	cmp al, '+'
+	je .fskip
+	test dx, 0x8000
+	jnz .fprnt
+	mov al, '-'
+.fprnt: int 0x10
+.fskip: shl dx, 1
+	loop .floop
+	call crlf
+	ret
+
+printreg:
+	push ax
+	mov al, dl
+	call putc
+	mov al, dh
+	call putc
+	mov al, '='
+	call putc
+	pop dx
+	call print16
+	call space
+	ret
+
 	; let the user edit the word at ES:BX
 edit_word:
 	push bx

debug/parse.asm

@@ -17,23 +17,17 @@ parse_error:
 	; Advance over whitespace
 	; IN	DS:SI
 eat_whitespace:
-	; peek on next char
+.loop:	lodsb
-	mov al, [si]
+	cmp al, 0x20
-	; ES := CS
+	je .loop
-	push es
+	cmp al, 0x0A
-	push cs
+	je .loop
-	pop es
+	cmp al, 0x0D
-	; string search
+	je .loop
-	mov di, .chars
+	cmp al, 0x09
-	mov cx, 4
+	je .loop
-	scasb
+	dec si
-	; restore bss segment
+	ret
-	pop es
-	jne .ret
-	inc si
-	jmp eat_whitespace
-.chars:	db 0x09, 0x0A, 0x0D, 0x20
-.ret:	ret
 
 	; Parse a register name
 	; IN	DS:SI	string to read

debug/run.asm

@@ -0,0 +1,83 @@
+; Commands related to executing debugged code
+
+cmd_g:	and word [reg_fl+1], 0xfe
+	jmp return
+
+cmd_t:	or word [reg_fl+1], 0x03
+	jmp return
+
+int3entry:
+	; save DS and load bss segment from IVT
+	push ds
+	mov ds, [cs:zero]
+	mov ds, [bssvec*4]
+	; save AX so we can work with it
+	mov [reg_ax], ax
+	; pop DS, IP, CS and flags from stack
+	pop ax
+	mov [reg_ds], ax
+	pop ax
+	mov [reg_ip], ax
+	pop ax
+	mov [reg_cs], ax
+	pop ax
+	mov [reg_fl], ax
+	; save the other registers
+	mov [reg_cx], cx
+	mov [reg_dx], dx
+	mov [reg_bx], bx
+	mov [reg_sp], sp
+	mov [reg_bp], bp
+	mov [reg_si], si
+	mov [reg_di], di
+	; save other segment registers we can access
+	mov [reg_ss], ss
+	mov [reg_es], es
+	; initialize other segments and setup stack
+	mov ax, ds
+	mov es, ax
+	mov ss, ax
+	mov sp, stack
+	call crlf
+	call printregs
+
+loop:	; show prompt
+	mov al, '-'
+	call putc
+	; read data
+	mov byte [inmin], 1
+	mov byte [inmax], 16
+	mov word [ingetc], getcu
+	call gets
+	pushf
+	call crlf
+	popf
+	jc loop
+	; execute
+	call runcmd
+	jmp loop
+
+return:	; restore stack pointer
+	mov ss, [reg_ss]
+	mov sp, [reg_sp]
+	; push flags, CS and IP
+	mov ax, [reg_fl]
+	push ax
+	mov ax, [reg_cs]
+	push ax
+	mov ax, [reg_ip]
+	push ax
+	; restore GPR
+	mov ax, [reg_ax]
+	mov cx, [reg_cx]
+	mov dx, [reg_dx]
+	mov bx, [reg_bx]
+	mov bp, [reg_bp]
+	mov si, [reg_si]
+	mov di, [reg_di]
+	; restore segment registers
+	; DS must be last
+	mov es, [reg_es]
+	mov ds, [reg_ds]
+	; final jump back
+	iret

debug/util.asm

@@ -0,0 +1,35 @@
+; Utility commands
+
+cmd_h:	call eat_whitespace
+	call eat_hex_word
+	jc .err
+
+	mov bx, dx
+
+	call eat_whitespace
+	call eat_hex_word
+	jc .err
+
+	xchg bx, dx
+
+	push dx
+	add dx, bx
+	call print16
+	call space
+	pop dx
+
+	sub dx, bx
+	call print16
+
+	jmp crlf
+.err:	mov di, eat_hex_word.emsg
+	jmp parse_error
+
+cmd_?:	mov si, .txt
+	jmp putcs
+.txt:	db "G       Go", 0x0A, 0x0D
+	db "H w w   Add and subtract two values", 0x0A, 0x0D
+	db "R[r]    Print register values", 0x0A, 0x0D
+	db "T       Single-Step", 0x0A, 0x0D
+	db 0
+

rom/debug.asm

@@ -57,93 +57,13 @@ init:	push ds
 	pop ds
 	retf
 
-	%include "debug/parse.asm"
-	%include "debug/chario.asm"
-	%include "debug/edit.asm"
-
-int3entry:
-	; save DS and load bss segment from IVT
-	push ds
-	mov ds, [cs:zero]
-	mov ds, [bssvec*4]
-	; save AX so we can work with it
-	mov [reg_ax], ax
-	; pop DS, IP, CS and flags from stack
-	pop ax
-	mov [reg_ds], ax
-	pop ax
-	mov [reg_ip], ax
-	pop ax
-	mov [reg_cs], ax
-	pop ax
-	mov [reg_fl], ax
-	; save the other registers
-	mov [reg_cx], cx
-	mov [reg_dx], dx
-	mov [reg_bx], bx
-	mov [reg_sp], sp
-	mov [reg_bp], bp
-	mov [reg_si], si
-	mov [reg_di], di
-	; save other segment registers we can access
-	mov [reg_ss], ss
-	mov [reg_es], es
-	; initialize other segments and setup stack
-	mov ax, ds
-	mov es, ax
-	mov ss, ax
-	mov sp, stack
-	call crlf
-	call printregs
-
-loop:	; show prompt
-	mov al, '-'
-	call putc
-	; read data
-	mov byte [inmin], 1
-	mov byte [inmax], 16
-	mov word [ingetc], getcu
-	call gets
-	pushf
-	call crlf
-	popf
-	jc loop
-	; execute
-	call runcmd
-	jmp loop
-
-return:	; restore stack pointer
-	mov ss, [reg_ss]
-	mov sp, [reg_sp]
-	; push flags, CS and IP
-	mov ax, [reg_fl]
-	push ax
-	mov ax, [reg_cs]
-	push ax
-	mov ax, [reg_ip]
-	push ax
-	; restore GPR
-	mov ax, [reg_ax]
-	mov cx, [reg_cx]
-	mov dx, [reg_dx]
-	mov bx, [reg_bx]
-	mov bp, [reg_bp]
-	mov si, [reg_si]
-	mov di, [reg_di]
-	; restore segment registers
-	; DS must be last
-	mov es, [reg_es]
-	mov ds, [reg_ds]
-	; final jump back
-	iret
-
-	%include "debug/names.asm"
-
 	; Expects DI to mark end of command
 runcmd:	mov si, inbuf
 	lodsb
 	cmp al, 'G'
 	je cmd_g
+	cmp al, 'H'
+	je cmd_h
 	cmp al, 'R'
 	je cmd_r
 	cmp al, 'T'
@@ -154,74 +74,13 @@ cerr:	mov al, '?'
 	call putc
 	jmp crlf
 
-cmd_?:	mov si, .txt
+	%include "debug/chario.asm"
-	jmp putcs
+	%include "debug/parse.asm"
-.txt:	db "G       Go", 0x0A, 0x0D
+	%include "debug/names.asm"
-	db "R[r]    Print register values", 0x0A, 0x0D
-	db "T       Single-Step", 0x0A, 0x0D
-	db 0
 
-cmd_g:	and word [reg_fl+1], 0xfe
+	%include "debug/edit.asm"
-	jmp return
+	%include "debug/run.asm"
-
+	%include "debug/util.asm"
-cmd_r:	cmp byte [si], 0
-	je printregs
-	call eat_register
-	jc .err
-	mov al, [cs:bx+rnames]
-	call putc
-	mov al, [cs:bx+rnames+1]
-	call putc
-	call space
-	call edit_word
-	call crlf
-	ret
-.err:	mov di, eat_register.emsg
-	jmp parse_error
-
-cmd_t:	or word [reg_fl+1], 0x03
-	jmp return
-
-printregs:
-	mov cx, 13
-	xor bx, bx
-	mov ah, 0x0e
-	mov si, reg_ax
-.loop:	push cx
-	mov dx, [cs:si+rnames]
-	lodsw
-	call printreg
-	pop cx
-	loop .loop
-
-	mov dx, [reg_fl]
-	mov si, fnames
-	mov cx, 16
-.floop:	mov al, [cs:si]
-	inc si
-	cmp al, '+'
-	je .fskip
-	test dx, 0x8000
-	jnz .fprnt
-	mov al, '-'
-.fprnt: int 0x10
-.fskip: shl dx, 1
-	loop .floop
-	call crlf
-	ret
-
-printreg:
-	push ax
-	mov al, dl
-	call putc
-	mov al, dh
-	call putc
-	mov al, '='
-	call putc
-	pop dx
-	call print16
-	call space
-	ret
 
 	align 512