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page ,132 title 87triga - inverse trigonometric functions - ASIN, ACOS, ATAN;*** ;87triga.asm - inverse trigonometric functions - ASIN, ACOS, ATAN;; Copyright (c) 1984-2001, Microsoft Corporation. All rights reserved.;;Purpose:; Routines for ASIN, ACOS, ATAN;;Revision History:;; 07/04/84 Greg Whitten; initial version;; 10/01/84 Brad Verheiden; Fixed bug in _rtforatnby0 which did not remove an; element from the floating stack;; 10/28/85 Jamie Bariteau; Added comment about inputs to fFATN2, made fFATN2; public; made _fFATN2 and _rtpiby2 public labels;; 10/30/87 Bill Johnston; Minor changes for new cmacros.;; 08/25/88 Bill Johnston; 386 version.;; 02/10/92 Georgios Papagiannakopoulos; NT port -- Bug fix for atan(-INF);; 03/27/92 GDP support underflow;; 01/03/96 JWM Modify return value of atan2(0,0);; 05/10/00 GB Modify return value for atan2(-0.0, 1.0);;*******************************************************************************
.xlist include cruntime.inc include mrt386.inc include elem87.inc.list
.data
extrn _indefinite:tbyteextrn _piby2:tbyte
jmptab OP_ATAN2,5,<'atan2',0>,<0,0,0,0,0,0>,2 DNCPTR codeoffset fFATN2 ; 0000 NOS Valid non-0, TOS Valid non-0 DNCPTR codeoffset _rtforatnby0 ; 0001 NOS Valid non-0, TOS 0 DNCPTR codeoffset _tosnan2 ; 0010 NOS Valid non-0, TOS NAN DNCPTR codeoffset _rtforatn20 ; 0011 NOS Valid non-0, TOS Inf DNCPTR codeoffset _rtforatn20 ; 0100 NOS 0, TOS Valid non-0 DNCPTR codeoffset _rtforatn20 ; 0101 NOS 0, TOS 0 DNCPTR codeoffset _tosnan2 ; 0110 NOS 0, TOS NAN DNCPTR codeoffset _rtforatn20 ; 0111 NOS 0, TOS Inf DNCPTR codeoffset _nosnan2 ; 1000 NOS NAN, TOS Valid non-0 DNCPTR codeoffset _nosnan2 ; 1001 NOS NAN, TOS 0 DNCPTR codeoffset _nan2 ; 1010 NOS NAN, TOS NAN DNCPTR codeoffset _nosnan2 ; 1011 NOS NAN, TOS Inf DNCPTR codeoffset _rtforatnby0 ; 1100 NOS Inf, TOS Valid non-0 DNCPTR codeoffset _rtforatnby0 ; 1101 NOS Inf, TOS 0 DNCPTR codeoffset _tosnan2 ; 1110 NOS Inf, TOS NAN DNCPTR codeoffset _rtindfpop ; 1111 NOS Inf, TOS Inf
page
CODESEG
extrn _rtchsifneg:nearextrn _rtindfpop:nearextrn _rtindfnpop:nearextrn _rtnospop:nearextrn _rtonenpop:nearextrn _rttospop:nearextrn _rttosnpop:nearextrn _rttosnpopde:nearextrn _rtzeronpop:nearextrn _tosnan1:nearextrn _tosnan2:nearextrn _nosnan2:nearextrn _nan2:near
;----------------------------------------------------------;; INVERSE TRIGONOMETRIC FUNCTIONS;;----------------------------------------------------------;; INPUTS - For single argument functions the argument; is the stack top. For fFATN2 the numerator; is next to stack top, the denominator is; the stack top.; For single argument functions the sign is; in bit 2 of CL. For fFATN2 the numerator; sign is bit 2 of CH, the denominator; sign is bit 2 of CL.;; Note:; _clog calls fFATN2 with the signs of the arguments; in bit 0 of CL and CH respectively. This should; work since fFATN2 tests for sign of numerator and; denominator by using "or CL,CL" and "or CH,CH";; OUTPUT - The result is the stack top;;----------------------------------------------------------
lab fFASN call AugmentSinCos ; num.=arg, den.=sqrt(1-arg^2) xchg ch, cl ; sign(num.)=sign(arg) jmp short fFPATAN
lab fFACS call AugmentSinCos ; num.=arg, den.=sqrt(1-arg^2) fxch ; num.=sqrt(1-arg^2), den.=arg jmp short fFPATAN
lab fFATN fabs fld1 ; denominator is 1 mov ch, cl xor cl, cl ; sign of denominator is +ve jmp short fFPATAN
labelNP _fFATN2, PUBLIClab fFATN2 mov DSF.ErrorType, CHECKRANGE ; indicate possible over/under flow on exit fabs fxch fabs fxch
lab fFPATAN fpatan ; compute partial arctangent or cl, cl ; if denominator was +ve JSZ PatanNumeratorTest ; bypass -ve denominator adjust fldpi fsubrp st(1), st(0) ; change Patan to pi - Patan
lab PatanNumeratorTest or ch, ch ; if numerator was +ve JSZ PatanDone ; bypass -ve numerator adjust fchs ; change Patan to -Patan
lab PatanDone ret
page
lab AugmentSinCos fabs ; NOS=x = |input| fld st(0) ; NOS=x, TOS=x fld st(0) ; NNOS=x, NOS=x, TOS=x fld1 ; NNNOS=x, NNOS=x, NOS=x, TOS=1 fsubrp st(1),st(0) ; NNOS=x, NOS=x, TOS=1-x fxch ; NNOS=x, NOS=1-x, TOS=x fld1 ; NNNOS=x, NNOS=1-x, NOS=x, TOS=1 fadd ; NNOS=x, NOS=1-x, TOS=1+x fmul ; NOS=x, TOS=1-x^2 ftst fstsw DSF.StatusWord fwait test CondCode, 1 ; if 1-x^2 < 0 JSNZ DescriminantNeg ; return a NAN xor ch, ch ; sign of TOS is +ve fsqrt ; NOS=x, TOS=sqrt(1-x^2) ret
lab DescriminantNeg pop rax ; remove return address from stack jmp _rtindfpop ; replace top of stack with a NAN
page;----------------------------------------------------------;; SPECIAL CASE RETURN FUNCTIONS;;----------------------------------------------------------;; INPUTS - The signs of the last, second to last; arguments are in CH, CL respectively.;; OUTPUT - The result is the stack top.;;----------------------------------------------------------
labelNP _rtpiby2, PUBLIC fstp st(0) ; remove ST(0) fld [_piby2] ; push pi/2 onto stack ret
lab _rtforatn20 fstp st(0) ; remove ST(0) or cl ,cl ; if denominator is +ve JSZ zeronpop ; return zero fstp st(0) fldpi ; push pi onto stack or ch, ch ; if numerator was +ve JSZ postv fchslab postv ret
lab zeronpop fstp st(0) fldz ; push 0.0 onto stack or ch, ch ; if numerator was +ve JSZ postv fchs ret
lab _rtforatn200lab indfpop fstp st(0) ; remove ST(0)lab indfnpop jmp _rtindfnpop ; return real indefinite
lab _rtforatnby0 fstp st(0) ; remove an argument before returning mov cl, ch ; cl is sign(TOS) jmp short _rtsignpiby2
lab _rtforatninflab _rtsignpiby2 call _rtpiby2 ; push pi/2 onto stack jmp _rtchsifneg ; return with sign change if negative
end
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