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74dfd0cf JM |
1 | /* $NetBSD: e_exp.S,v 1.14 2008/06/23 10:24:13 drochner Exp $ */ |

2 | ||

b34b60bc JS |
3 | /* |

4 | * Copyright (c) 1993,94 Winning Strategies, Inc. | |

5 | * All rights reserved. | |

6 | * | |

7 | * Redistribution and use in source and binary forms, with or without | |

8 | * modification, are permitted provided that the following conditions | |

9 | * are met: | |

10 | * 1. Redistributions of source code must retain the above copyright | |

11 | * notice, this list of conditions and the following disclaimer. | |

12 | * 2. Redistributions in binary form must reproduce the above copyright | |

13 | * notice, this list of conditions and the following disclaimer in the | |

14 | * documentation and/or other materials provided with the distribution. | |

15 | * 3. All advertising materials mentioning features or use of this software | |

16 | * must display the following acknowledgement: | |

17 | * This product includes software developed by Winning Strategies, Inc. | |

18 | * 4. The name of the author may not be used to endorse or promote products | |

19 | * derived from this software without specific prior written permission. | |

20 | * | |

21 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |

22 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |

23 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |

24 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |

25 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |

26 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |

27 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |

28 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |

29 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |

30 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |

b34b60bc JS |
31 | */ |

32 | ||

33 | /* | |

34 | * Written by: | |

35 | * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. | |

36 | */ | |

37 | ||

38 | #include <machine/asm.h> | |

39 | ||

40 | #include "abi.h" | |

41 | ||

42 | ||

43 | /* e^x = 2^(x * log2(e)) */ | |

44 | ENTRY(exp) | |

74dfd0cf | 45 | XMM_ONE_ARG_DOUBLE_PROLOGUE |

b34b60bc JS |
46 | /* |

47 | * If x is +-Inf, then the subtraction would give Inf-Inf = NaN. | |

48 | * Avoid this. Also avoid it if x is NaN for convenience. | |

49 | */ | |

74dfd0cf JM |
50 | movl ARG_DOUBLE_ONE_MSW, %eax |

51 | andl $0x7fffffff, %eax | |

52 | cmpl $0x7ff00000, %eax | |

b34b60bc JS |
53 | jae x_Inf_or_NaN |

54 | ||

74dfd0cf | 55 | fldl ARG_DOUBLE_ONE |

b34b60bc JS |
56 | |

57 | /* | |

58 | * Ensure that the rounding mode is to nearest (to give the smallest | |

59 | * possible fraction) and that the precision is as high as possible. | |

60 | * We may as well mask interrupts if we switch the mode. | |

61 | */ | |

74dfd0cf JM |
62 | #define CWSTORE_SAV ARG_DOUBLE_ONE_LSW /* XXX overwrites the argument */ |

63 | #define CWSTORE_TMP ARG_DOUBLE_ONE_MSW | |

64 | fstcw CWSTORE_SAV | |

65 | movl CWSTORE_SAV, %eax | |

66 | andl $0x0f00, %eax | |

67 | cmpl $0x0300, %eax /* RC == 0 && PC == 3? */ | |

b34b60bc | 68 | je 1f /* jump if mode is good */ |

74dfd0cf JM |
69 | movl $0x137f, CWSTORE_TMP |

70 | fldcw CWSTORE_TMP | |

b34b60bc JS |
71 | 1: |

72 | fldl2e | |

73 | fmulp /* x * log2(e) */ | |

74 | fst %st(1) | |

75 | frndint /* int(x * log2(e)) */ | |

76 | fst %st(2) | |

77 | fsubrp /* fract(x * log2(e)) */ | |

78 | f2xm1 /* 2^(fract(x * log2(e))) - 1 */ | |

79 | fld1 | |

80 | faddp /* 2^(fract(x * log2(e))) */ | |

81 | fscale /* e^x */ | |

82 | fstp %st(1) | |

83 | je 1f | |

74dfd0cf | 84 | fldcw CWSTORE_SAV |

b34b60bc | 85 | 1: |

74dfd0cf | 86 | XMM_DOUBLE_EPILOGUE |

b34b60bc | 87 | ret |

b34b60bc JS |
88 | x_Inf_or_NaN: |

89 | /* | |

90 | * Return 0 if x is -Inf. Otherwise just return x, although the | |

91 | * C version would return (x + x) (Real Indefinite) if x is a NaN. | |

92 | */ | |

74dfd0cf | 93 | cmpl $0xfff00000, ARG_DOUBLE_ONE_MSW |

b34b60bc | 94 | jne x_not_minus_Inf |

74dfd0cf | 95 | cmpl $0, ARG_DOUBLE_ONE_LSW |

b34b60bc JS |
96 | jne x_not_minus_Inf |

97 | fldz | |

74dfd0cf | 98 | XMM_DOUBLE_EPILOGUE |

b34b60bc JS |
99 | ret |

100 | ||

101 | x_not_minus_Inf: | |

74dfd0cf JM |
102 | fldl ARG_DOUBLE_ONE |

103 | XMM_DOUBLE_EPILOGUE | |

b34b60bc | 104 | ret |

d04e8698 | 105 | END(exp) |

70e34eb2 JM |
106 | |

107 | .section .note.GNU-stack,"",%progbits |