Revamp debugger, including support for printing padded numbers

kernel/debug.asm

@@ -1,3 +1,93 @@
+; Names for words in debug frame
+; Two characters per word, 14 words total
+debug_frame_names:
+  ; general-purpose registers
+  db "AXBXCXDXSPBPSIDI"
+  ; extra registers
+  db "DSESSSIPCSFL"
+
+; Names for bits in debug_frame+26 (FL/Flags register)
+; One character per bit, 16 bits total
+debug_frame_flags:
+  db "++++ODIT"
+  db "SZ+A+P+C"
+
+; Print a single register from the frame
+; in	SI	frame offset for register
+debug_frame_register_print:
+  mov bx, debug_frame_names
+  mov al, [cs:bx+si] ; first name char load
+  call putc
+  mov al, [cs:bx+si+1] ; second name char load
+  call putc
+  mov al, '='
+  call putc
+  mov ax, [ss:bp+si] ; value load
+  ; prepare call to print_number
+  push bx
+  push cx
+  mov bx, 0x0010
+  mov cx, 3
+  call print_number_padded
+  pop cx
+  pop bx
+  mov al, ' '
+  call putc
+  ret
+
+debug_frame_print:
+  mov si, 0
+  mov cx, 8
+.reg1loop:
+  call debug_frame_register_print
+  add si, 2
+  loop .reg1loop
+
+  mov dx, [ss:bp+26]
+  mov di, debug_frame_flags
+  mov cx, 0x0010
+.flag_loop:
+  mov al, [cs:di]
+  inc di
+  cmp al, '+'
+  je .next
+  test dx, 0x8000
+  jnz .write
+  mov al, '-'
+.write:
+  call putc
+.next:
+  sal dx, 1
+  loop .flag_loop
+
+  call printf
+  db 0x0A, 0x0D, 0
+
+  mov si, 16
+  mov cx, 3
+.reg2loop:
+  call debug_frame_register_print
+  add si, 2
+  loop .reg2loop
+
+  mov ax, [bp+24]
+  mov bx, 0x0010
+  mov cx, 3
+  call print_number_padded
+
+  mov al, ':'
+  call putc
+
+  mov ax, [bp+22]
+  mov bx, 0x0010
+  mov cx, 3
+  call print_number_padded
+
+  call printf
+  db 0x0A, 0x0D, 0
+
+  ret
+
 ; this prints registers
 ; expect to be called as interrupt routine
 isr_debug:
@@ -13,41 +103,24 @@ isr_debug:
   push bx
   push ax
 
-  call printf
-  db "AX=%X BX=%X CX=%X DX=%X", 0x20
-  db "SP=%X BP=%X SI=%X DI=%X", 0x0A, 0x0D
-  db "DS=%X ES=%X SS=%X IP=%X CS=%X", 0x20, 0
-
   mov bp, sp
-  mov bx, [ss:bp+26]
-  mov si, .flags
-  mov cx, 0x0010
-.loop:
-  mov al, [cs:si]
-  inc si
-  test bx, 0x8000
-  jnz .write
-  mov al, '-'
-.write:
-  sal bx, 1
-  call putc
-  loop .loop
+  mov [bp+08], bp
+  add WORD [bp+08], 28
 
   call printf
   db 0x0A, 0x0D, 0
 
+  call debug_frame_print
+
   pop ax
   pop bx
   pop cx
   pop dx
-  pop sp
+  pop bp ; sp to be ignored
   pop bp
   pop si
   pop di
   pop ds
   pop es
   pop ss
-  iret
-.flags:
-  ; 16 letters for each bit in flags register
-  db "++++ODITSZ+A+P+C"
+  iret