UNIX 6th Ed. - /usr/source/salloc/bsp.s

   1: .globl  backspace
   2: .globl  lookchar
   3: .globl  w, r, a, l
   4: /
   5: /	routine to read a string backwards
   6: /	the read pointer is decremented before reading
   7: /
   8: /	mov	...,r1
   9: /	jsr	pc,backspace
  10: /	mov	r0,...
  11: /
  12: backspace:
  13:         cmp     a(r1),r(r1)
  14:         bhis    nochc
  15:         dec     r(r1)
  16:         jsr     pc,lookchar
  17:         rts     pc
  18: nochc:  clr     r0
  19:         sec
  20:         rts     pc

Defined functions