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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v102a/libe/iefatan.s

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+         ttl       ieee format equivalent arctangent (iefatan)
+***************************************
+* (c) copyright 1981 by motorola inc. *
+***************************************
+ 
+*************************************************
+*                  iefatan                      *
+*     ieee format equivalent arctangent         *
+*                                               *
+*  input:   d7 - ieee format argument           *
+*                                               *
+*  output:  d7 - ieee format arctangent radian  *
+*                result                         *
+*                                               *
+*     all other registers totally transparent   *
+*                                               *
+*  condition codes:                             *
+*        z - set if result is zero              *
+*        n - cleared                            *
+*        v - set if result is nan (not-a-number)*
+*            (set if the input argument was nan)
+*        c - undefined                          *
+*        x - undefined                          *
+*                                               *
+*          all other registers transparent      *
+*                                               *
+*          maximum stack used:   54 bytes       *
+*                                               *
+*                                               *
+*  notes:                                       *
+*    1) see the mc68344 user's guide for details*
+*       on ieee format range limitations.       *
+*    2) spot checks show at least six digit     *
+*       precision on all sampled cases.         *
+*                                               *
+*************************************************
+         page
+iefatan  idnt  1,1 ieee format equivalent arctangent
+ 
+         opt       pcs
+ 
+         section   9
+ 
+         xdef      iefatan                       entry point
+ 
+         xref      ffpatan                fast floating point arctangent
+         xref      iefsop            front-end single operand convert
+         xref      ieftieee          back-end return ieee format
+         xref      ffpfieee          ffp to ieee convert routine
+         xref      ffpcpyrt            copyright stub
+ 
+********************
+* arctangent entry *
+********************
+ 
+* save registers and convert argument
+iefatan  jsr       iefsop    convert the single argument
+         bra.s     iefnrm    +0 branch normalized
+* argument was infinite                  +2 infinity
+         jsr       ffpfieee  convert to maximum values allowed in ffp format
+ 
+* argument was normalized
+iefnrm   jsr       ffpatan   call ffp arctangent routine
+         jmp       ieftieee  return in ieee format
+ 
+         end
+