fdn086.asm

来自「开放源码的编译器open watcom 1.6.0版的源代码」· 汇编 代码 · 共 66 行

;*****************************************************************************
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;*                            Open Watcom Project
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;*  ========================================================================
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;========================================================================
;==     Name:           FDN                                            ==
;==     Operation:      Floating double negate                         ==
;==     Inputs:         AX      high word of float                     ==
;==     Outputs:        AX      new high word of float                 ==
;==     Volatile:       none                                           ==
;========================================================================
include mdef.inc
include struct.inc

        modstart        fdn086

        xdefp   __FDN

        defpe   __FDN
        test    ax,ax           ; if non zero number then
        _if     e
          test  dx,dx
          _if   e
            test bx,bx
            _if e
              test cx,cx
            _endif
          _endif
        _endif
        _if     ne              ; ...
          xor   ah,80h          ; - flip the sign bit
        _endif                  ; endif
        ret                     ; and return!!!
        endproc __FDN

        endmod
        end