fuchsia / third_party / dropbear / refs/tags/DROPBEAR_0.50 / . / libtommath / bn_mp_reduce_is_2k_l.c

#include <tommath.h> | |

#ifdef BN_MP_REDUCE_IS_2K_L_C | |

/* LibTomMath, multiple-precision integer library -- Tom St Denis | |

* | |

* LibTomMath is a library that provides multiple-precision | |

* integer arithmetic as well as number theoretic functionality. | |

* | |

* The library was designed directly after the MPI library by | |

* Michael Fromberger but has been written from scratch with | |

* additional optimizations in place. | |

* | |

* The library is free for all purposes without any express | |

* guarantee it works. | |

* | |

* Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com | |

*/ | |

/* determines if reduce_2k_l can be used */ | |

int mp_reduce_is_2k_l(mp_int *a) | |

{ | |

int ix, iy; | |

if (a->used == 0) { | |

return MP_NO; | |

} else if (a->used == 1) { | |

return MP_YES; | |

} else if (a->used > 1) { | |

/* if more than half of the digits are -1 we're sold */ | |

for (iy = ix = 0; ix < a->used; ix++) { | |

if (a->dp[ix] == MP_MASK) { | |

++iy; | |

} | |

} | |

return (iy >= (a->used/2)) ? MP_YES : MP_NO; | |

} | |

return MP_NO; | |

} | |

#endif | |

/* $Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k_l.c,v $ */ | |

/* $Revision: 1.3 $ */ | |

/* $Date: 2006/03/31 14:18:44 $ */ |