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Diffstat (limited to 'sys/gnu/fpemul/poly_tan.c')
| -rw-r--r-- | sys/gnu/fpemul/poly_tan.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/sys/gnu/fpemul/poly_tan.c b/sys/gnu/fpemul/poly_tan.c new file mode 100644 index 000000000000..b167bd51a904 --- /dev/null +++ b/sys/gnu/fpemul/poly_tan.c @@ -0,0 +1,229 @@ +/* + * poly_tan.c + * + * Compute the tan of a FPU_REG, using a polynomial approximation. + * + * + * Copyright (C) 1992,1993,1994 + * W. Metzenthen, 22 Parker St, Ormond, Vic 3163, + * Australia. E-mail billm@vaxc.cc.monash.edu.au + * All rights reserved. + * + * This copyright notice covers the redistribution and use of the + * FPU emulator developed by W. Metzenthen. It covers only its use + * in the 386BSD, FreeBSD and NetBSD operating systems. Any other + * use is not permitted under this copyright. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must include information specifying + * that source code for the emulator is freely available and include + * either: + * a) an offer to provide the source code for a nominal distribution + * fee, or + * b) list at least two alternative methods whereby the source + * can be obtained, e.g. a publically accessible bulletin board + * and an anonymous ftp site from which the software can be + * downloaded. + * 3. All advertising materials specifically mentioning features or use of + * this emulator must acknowledge that it was developed by W. Metzenthen. + * 4. The name of W. Metzenthen may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY + * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL + * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * + * The purpose of this copyright, based upon the Berkeley copyright, is to + * ensure that the covered software remains freely available to everyone. + * + * The software (with necessary differences) is also available, but under + * the terms of the GNU copyleft, for the Linux operating system and for + * the djgpp ms-dos extender. + * + * W. Metzenthen June 1994. + * + * + * $Id: poly_tan.c,v 1.4 1994/06/10 07:44:42 rich Exp $ + * + */ + +#include "exception.h" +#include "reg_constant.h" +#include "fpu_emu.h" +#include "control_w.h" + + +#define HIPOWERop 3 /* odd poly, positive terms */ +static unsigned short oddplterms[HIPOWERop][4] = +{ + {0x846a, 0x42d1, 0xb544, 0x921f}, + {0x6fb2, 0x0215, 0x95c0, 0x099c}, + {0xfce6, 0x0cc8, 0x1c9a, 0x0000} +}; +#define HIPOWERon 2 /* odd poly, negative terms */ +static unsigned short oddnegterms[HIPOWERon][4] = +{ + {0x6906, 0xe205, 0x25c8, 0x8838}, + {0x1dd7, 0x3fe3, 0x944e, 0x002c} +}; +#define HIPOWERep 2 /* even poly, positive terms */ +static unsigned short evenplterms[HIPOWERep][4] = +{ + {0xdb8f, 0x3761, 0x1432, 0x2acf}, + {0x16eb, 0x13c1, 0x3099, 0x0003} +}; +#define HIPOWERen 2 /* even poly, negative terms */ +static unsigned short evennegterms[HIPOWERen][4] = +{ + {0x3a7c, 0xe4c5, 0x7f87, 0x2945}, + {0x572b, 0x664c, 0xc543, 0x018c} +}; + + +/*--- poly_tan() ------------------------------------------------------------+ + | | + +---------------------------------------------------------------------------*/ +void +poly_tan(FPU_REG * arg, FPU_REG * y_reg) +{ + char invert = 0; + short exponent; + FPU_REG odd_poly, even_poly, pos_poly, neg_poly; + FPU_REG argSq; + long long arg_signif, argSqSq; + + + exponent = arg->exp - EXP_BIAS; + + if (arg->tag == TW_Zero) { + /* Return 0.0 */ + reg_move(&CONST_Z, y_reg); + return; + } + if (exponent >= -1) { + /* argument is in the range [0.5 .. 1.0] */ + if (exponent >= 0) { +#ifdef PARANOID + if ((exponent == 0) && + (arg->sigl == 0) && (arg->sigh == 0x80000000)) +#endif /* PARANOID */ + { + arith_overflow(y_reg); + return; + } +#ifdef PARANOID + EXCEPTION(EX_INTERNAL | 0x104); /* There must be a logic + * error */ + return; +#endif /* PARANOID */ + } + /* The argument is in the range [0.5 .. 1.0) */ + /* Convert the argument to a number in the range (0.0 .. 0.5] */ + *((long long *) (&arg->sigl)) = -*((long long *) (&arg->sigl)); + normalize(arg); /* Needed later */ + exponent = arg->exp - EXP_BIAS; + invert = 1; + } +#ifdef PARANOID + if (arg->sign != 0) { /* Can't hack a number < 0.0 */ + arith_invalid(y_reg); + return; + } /* Need a positive number */ +#endif /* PARANOID */ + + *(long long *) &arg_signif = *(long long *) &(arg->sigl); + if (exponent < -1) { + /* shift the argument right by the required places */ + if (shrx(&arg_signif, -1 - exponent) >= (unsigned)0x80000000) + arg_signif++; /* round up */ + } + mul64(&arg_signif, &arg_signif, (long long *) (&argSq.sigl)); + mul64((long long *) (&argSq.sigl), (long long *) (&argSq.sigl), &argSqSq); + + /* will be a valid positive nr with expon = 0 */ + *(short *) &(pos_poly.sign) = 0; + pos_poly.exp = EXP_BIAS; + + /* Do the basic fixed point polynomial evaluation */ + polynomial((u_int *) &pos_poly.sigl, (unsigned *) &argSqSq, oddplterms, HIPOWERop - 1); + + /* will be a valid positive nr with expon = 0 */ + *(short *) &(neg_poly.sign) = 0; + neg_poly.exp = EXP_BIAS; + + /* Do the basic fixed point polynomial evaluation */ + polynomial((u_int *) &neg_poly.sigl, (unsigned *) &argSqSq, oddnegterms, HIPOWERon - 1); + mul64((long long *) (&argSq.sigl), (long long *) (&neg_poly.sigl), + (long long *) (&neg_poly.sigl)); + + /* Subtract the mantissas */ + *((long long *) (&pos_poly.sigl)) -= *((long long *) (&neg_poly.sigl)); + + /* Convert to 64 bit signed-compatible */ + pos_poly.exp -= 1; + + reg_move(&pos_poly, &odd_poly); + normalize(&odd_poly); + + reg_mul(&odd_poly, arg, &odd_poly, FULL_PRECISION); + reg_u_add(&odd_poly, arg, &odd_poly, FULL_PRECISION); /* This is just the odd + * polynomial */ + + + /* will be a valid positive nr with expon = 0 */ + *(short *) &(pos_poly.sign) = 0; + pos_poly.exp = EXP_BIAS; + + /* Do the basic fixed point polynomial evaluation */ + polynomial((u_int *) &pos_poly.sigl, (unsigned *) &argSqSq, evenplterms, HIPOWERep - 1); + mul64((long long *) (&argSq.sigl), + (long long *) (&pos_poly.sigl), (long long *) (&pos_poly.sigl)); + + /* will be a valid positive nr with expon = 0 */ + *(short *) &(neg_poly.sign) = 0; + neg_poly.exp = EXP_BIAS; + + /* Do the basic fixed point polynomial evaluation */ + polynomial((u_int *) &neg_poly.sigl, (unsigned *) &argSqSq, evennegterms, HIPOWERen - 1); + + /* Subtract the mantissas */ + *((long long *) (&neg_poly.sigl)) -= *((long long *) (&pos_poly.sigl)); + /* and multiply by argSq */ + + /* Convert argSq to a valid reg number */ + *(short *) &(argSq.sign) = 0; + argSq.exp = EXP_BIAS - 1; + normalize(&argSq); + + /* Convert to 64 bit signed-compatible */ + neg_poly.exp -= 1; + + reg_move(&neg_poly, &even_poly); + normalize(&even_poly); + + reg_mul(&even_poly, &argSq, &even_poly, FULL_PRECISION); + reg_add(&even_poly, &argSq, &even_poly, FULL_PRECISION); + reg_sub(&CONST_1, &even_poly, &even_poly, FULL_PRECISION); /* This is just the even + * polynomial */ + + /* Now ready to copy the results */ + if (invert) { + reg_div(&even_poly, &odd_poly, y_reg, FULL_PRECISION); + } else { + reg_div(&odd_poly, &even_poly, y_reg, FULL_PRECISION); + } + +} |