ctell.mac

来自「--- --- ---基于C语言的编译器的 简单实现」· MAC 代码 · 共 90 行

 INCLUDE PROLOG.H
 EXTRN _Ufd:WORD
_CC1:
 PUBLIC _tell
_tell:
 MOV BX,6
 ADD BX,SP
 MOV BX,[BX]
 PUSH BX  ;
 CALL _Umode
 ADD SP,2
 OR BX,BX
 MOV BX,CX
 JNZ $+3
 INC BX
 OR BX,BX
 JZ $+5
 JMP _CC4
 MOV BX,6
 ADD BX,SP
 MOV BX,[BX]
 PUSH BX  ;
 CALL _isatty
 ADD SP,2
 OR BX,BX
 JZ $+5
 JMP _CC4
 MOV BX,0
 JMP _CC5
_CC4:
 MOV BX,1
_CC5:
 OR BX,BX
 JNZ $+5
 JMP _CC3
 MOV BX,-1
 RET
_CC3:
 MOV BX,4
 ADD BX,SP
 MOV BX,[BX]
 PUSH BX  ;
 MOV BX,4
 ADD BX,SP
 MOV BX,[BX]
 PUSH BX  ;
 MOV BX,OFFSET _Ufd
 XCHG DX,BX
 MOV BX,10
 ADD BX,SP
 MOV BX,[BX]
 ADD BX,BX
 ADD BX,DX
 MOV BX,[BX]
 PUSH BX  ;
 CALL _utell
 ADD SP,6
 RET
 PUBLIC _utell
_utell:
  POP SI  ;Return address
  POP BX  ;Handle
  PUSH BX ;Restore
  PUSH SI
  XOR DX,DX ;Zero in DX
; Move file pointer 0 from current location
; this will return current location in DX:AX
  MOV AX,4201H
  INT 21H
  JC UTELLC1  ;Jump if error
  MOV BP,SP   ;Get SP
  MOV SI,[BP+6] ;offset lo
  MOV [SI],AX   ;move it in
  MOV SI,[BP+4] ;Offset hi
  MOV [SI],DX   ;Move it in
  XOR AX,AX     ;Return no error
  JMP UTELLC2
 UTELLC1: 
  MOV _ERRNO,AX  ;Return error
  MOV AX,-2
 UTELLC2:
  MOV BX,AX
  XOR CX,CX     ;Zero in CX
  EXTRN _ERRNO:WORD
 RET
 EXTRN _isatty:NEAR
 EXTRN _Umode:NEAR
 INCLUDE EPILOG.H
 END