Annotation of sys/arch/m68k/fpsp/sacos.sa, Revision 1.1
1.1 ! nbrk 1: * $OpenBSD: sacos.sa,v 1.2 1996/05/29 21:05:34 niklas Exp $
! 2: * $NetBSD: sacos.sa,v 1.3 1994/10/26 07:49:27 cgd Exp $
! 3:
! 4: * MOTOROLA MICROPROCESSOR & MEMORY TECHNOLOGY GROUP
! 5: * M68000 Hi-Performance Microprocessor Division
! 6: * M68040 Software Package
! 7: *
! 8: * M68040 Software Package Copyright (c) 1993, 1994 Motorola Inc.
! 9: * All rights reserved.
! 10: *
! 11: * THE SOFTWARE is provided on an "AS IS" basis and without warranty.
! 12: * To the maximum extent permitted by applicable law,
! 13: * MOTOROLA DISCLAIMS ALL WARRANTIES WHETHER EXPRESS OR IMPLIED,
! 14: * INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
! 15: * PARTICULAR PURPOSE and any warranty against infringement with
! 16: * regard to the SOFTWARE (INCLUDING ANY MODIFIED VERSIONS THEREOF)
! 17: * and any accompanying written materials.
! 18: *
! 19: * To the maximum extent permitted by applicable law,
! 20: * IN NO EVENT SHALL MOTOROLA BE LIABLE FOR ANY DAMAGES WHATSOEVER
! 21: * (INCLUDING WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS
! 22: * PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR
! 23: * OTHER PECUNIARY LOSS) ARISING OF THE USE OR INABILITY TO USE THE
! 24: * SOFTWARE. Motorola assumes no responsibility for the maintenance
! 25: * and support of the SOFTWARE.
! 26: *
! 27: * You are hereby granted a copyright license to use, modify, and
! 28: * distribute the SOFTWARE so long as this entire notice is retained
! 29: * without alteration in any modified and/or redistributed versions,
! 30: * and that such modified versions are clearly identified as such.
! 31: * No licenses are granted by implication, estoppel or otherwise
! 32: * under any patents or trademarks of Motorola, Inc.
! 33:
! 34: *
! 35: * sacos.sa 3.3 12/19/90
! 36: *
! 37: * Description: The entry point sAcos computes the inverse cosine of
! 38: * an input argument; sAcosd does the same except for denormalized
! 39: * input.
! 40: *
! 41: * Input: Double-extended number X in location pointed to
! 42: * by address register a0.
! 43: *
! 44: * Output: The value arccos(X) returned in floating-point register Fp0.
! 45: *
! 46: * Accuracy and Monotonicity: The returned result is within 3 ulps in
! 47: * 64 significant bit, i.e. within 0.5001 ulp to 53 bits if the
! 48: * result is subsequently rounded to double precision. The
! 49: * result is provably monotonic in double precision.
! 50: *
! 51: * Speed: The program sCOS takes approximately 310 cycles.
! 52: *
! 53: * Algorithm:
! 54: *
! 55: * ACOS
! 56: * 1. If |X| >= 1, go to 3.
! 57: *
! 58: * 2. (|X| < 1) Calculate acos(X) by
! 59: * z := (1-X) / (1+X)
! 60: * acos(X) = 2 * atan( sqrt(z) ).
! 61: * Exit.
! 62: *
! 63: * 3. If |X| > 1, go to 5.
! 64: *
! 65: * 4. (|X| = 1) If X > 0, return 0. Otherwise, return Pi. Exit.
! 66: *
! 67: * 5. (|X| > 1) Generate an invalid operation by 0 * infinity.
! 68: * Exit.
! 69: *
! 70:
! 71: SACOS IDNT 2,1 Motorola 040 Floating Point Software Package
! 72:
! 73: section 8
! 74:
! 75: PI DC.L $40000000,$C90FDAA2,$2168C235,$00000000
! 76: PIBY2 DC.L $3FFF0000,$C90FDAA2,$2168C235,$00000000
! 77:
! 78: xref t_operr
! 79: xref t_frcinx
! 80: xref satan
! 81:
! 82: xdef sacosd
! 83: sacosd:
! 84: *--ACOS(X) = PI/2 FOR DENORMALIZED X
! 85: fmove.l d1,fpcr ...load user's rounding mode/precision
! 86: FMOVE.X PIBY2,FP0
! 87: bra t_frcinx
! 88:
! 89: xdef sacos
! 90: sacos:
! 91: FMOVE.X (a0),FP0 ...LOAD INPUT
! 92:
! 93: move.l (a0),d0 ...pack exponent with upper 16 fraction
! 94: move.w 4(a0),d0
! 95: ANDI.L #$7FFFFFFF,D0
! 96: CMPI.L #$3FFF8000,D0
! 97: BGE.B ACOSBIG
! 98:
! 99: *--THIS IS THE USUAL CASE, |X| < 1
! 100: *--ACOS(X) = 2 * ATAN( SQRT( (1-X)/(1+X) ) )
! 101:
! 102: FMOVE.S #:3F800000,FP1
! 103: FADD.X FP0,FP1 ...1+X
! 104: FNEG.X FP0 ... -X
! 105: FADD.S #:3F800000,FP0 ...1-X
! 106: FDIV.X FP1,FP0 ...(1-X)/(1+X)
! 107: FSQRT.X FP0 ...SQRT((1-X)/(1+X))
! 108: fmovem.x fp0,(a0) ...overwrite input
! 109: move.l d1,-(sp) ;save original users fpcr
! 110: clr.l d1
! 111: bsr satan ...ATAN(SQRT([1-X]/[1+X]))
! 112: fMOVE.L (sp)+,fpcr ;restore users exceptions
! 113: FADD.X FP0,FP0 ...2 * ATAN( STUFF )
! 114: bra t_frcinx
! 115:
! 116: ACOSBIG:
! 117: FABS.X FP0
! 118: FCMP.S #:3F800000,FP0
! 119: fbgt t_operr ;cause an operr exception
! 120:
! 121: *--|X| = 1, ACOS(X) = 0 OR PI
! 122: move.l (a0),d0 ...pack exponent with upper 16 fraction
! 123: move.w 4(a0),d0
! 124: TST.L D0 ;D0 has original exponent+fraction
! 125: BGT.B ACOSP1
! 126:
! 127: *--X = -1
! 128: *Returns PI and inexact exception
! 129: FMOVE.X PI,FP0
! 130: FMOVE.L d1,FPCR
! 131: FADD.S #:00800000,FP0 ;cause an inexact exception to be put
! 132: * ;into the 040 - will not trap until next
! 133: * ;fp inst.
! 134: bra t_frcinx
! 135:
! 136: ACOSP1:
! 137: FMOVE.L d1,FPCR
! 138: FMOVE.S #:00000000,FP0
! 139: rts ;Facos of +1 is exact
! 140:
! 141: end
CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to sacos.sa CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / sys / arch / m68k / fpsp