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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v102a/orglibe/iefexp.s

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+         ttl       ieee format equivalent exponent (iefexp)
+***************************************
+* (c) copyright 1981 by motorola inc. *
+***************************************
+ 
+*************************************************
+*                  iefexp                       *
+* ieee format equivalent exponent function      *
+*                                               *
+*  input:   d7 - ieee floating point argument   *
+*                                               *
+*  output:  d7 - ieee floating point exponential*
+*                result                         *
+*                                               *
+*     all other registers are transparent       *
+*                                               *
+*       maximum stack used:   54 bytes          *
+*                                               *
+*  condition codes:                             *
+*        z - set if result in d7 is zero        *
+*        n - cleared                            *
+*        v - set if result is nan (not-a-number)*
+*        c - undefined                          *
+*        x - undefined                          *
+*                                               *
+*                                               *
+*  notes:                                       *
+*    1) if the input argument is a nan (not-a-  *
+*       number) then the "v" bit will be set    *
+*       and the argument unchanged upon return. *
+*    2) see the mc68344 user's guide for details*
+*       on the range of ieee normalized values  *
+*       supported.                              *
+*    2) spot checks show at least 6.8 digit     *
+*       accuracy for all abs(arg) < 30.         *
+*                                               *
+*************************************************
+         page
+iefexp   idnt  1,1 ieee format equivalent exp
+ 
+         opt       pcs
+ 
+         section   9
+ 
+         xdef      iefexp                        entry point
+ 
+         xref      ffpexp            fast floating point exponent
+         xref      iefsop            front-end single argument routine
+         xref      ieftieee         back-end return to ieee format
+         xref      iefrtd7          return to caller argument in d7
+         xref      ffpcpyrt            copyright stub
+ 
+************************
+* exponent entry point *
+************************
+iefexp   jsr       iefsop    convert argument to ffp format
+         bra.s     iefnrm    branch normalized
+* argument is an infinity
+         bpl.s     iefdrtn   branch if plus - return itself
+         move.l    #0,d7     return plus zero if was negative infinity
+iefdrtn  jmp       iefrtd7   return the result that is in d7
+ 
+* argument is normalized
+iefnrm   jsr       ffpexp    call fast floating point exponent function
+         jmp       ieftieee  and return in ieee format
+ 
+         end