rdos/bdos/dump.asm

; print a word
; in: ax
print16:
  xchg ah,al
  call print8
  xchg ah,al

; print a byte
; in: al
print8:
  push ax ; avoid destroying ah
  push bx
  xor bx, bx
  aam 16 ; high nibble moved into ah, low nibble into al
  add ax, 0x3030
  push ax
  xchg al, ah
  call .nib
  pop ax
  call .nib
  pop bx
  pop ax
  ret
.nib:
  cmp al, 0x3a
  jl .out
  add al, 0x07
.out:
  mov dl, al
  call CONOUT
  ret

dump:
  push ax
  push cx
  push dx
  push bx
  mov dl, 0x0A
  call CONOUT
  mov dl, 0x0D
  call CONOUT
  mov cx, 4
.loop_line:
  push cx
  push bx
  mov ax, bx
  call print16
  mov dl, ':'
  call CONOUT
  mov dl, ' '
  call CONOUT
  mov cx, 0x8
.loop_bin:
  mov ax, [bx]
  xchg al, ah
  inc bx
  inc bx
  call print16
  mov dl, ' '
  call CONOUT
  loop .loop_bin
  pop bx
  mov cx, 0x10
.loop_ascii:
  mov dl, '.'
  cmp byte [bx], 0x20
  jc .print
  cmp byte [bx], 0x80
  jnc .print
  mov dl, [bx]
.print:
  inc bx
  call CONOUT
  loop .loop_ascii
  pop cx
  mov dl, 0x0A
  call CONOUT
  mov dl, 0x0D
  call CONOUT
  loop .loop_line
  pop bx
  pop dx
  pop cx
  pop ax
  ret