diff options
Diffstat (limited to 'drivers/FPU-emu/poly_2xm1.c')
| -rw-r--r-- | drivers/FPU-emu/poly_2xm1.c | 152 |
1 files changed, 0 insertions, 152 deletions
diff --git a/drivers/FPU-emu/poly_2xm1.c b/drivers/FPU-emu/poly_2xm1.c deleted file mode 100644 index f7c585d60..000000000 --- a/drivers/FPU-emu/poly_2xm1.c +++ /dev/null @@ -1,152 +0,0 @@ -/*---------------------------------------------------------------------------+ - | poly_2xm1.c | - | | - | Function to compute 2^x-1 by 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 | - | | - | | - +---------------------------------------------------------------------------*/ - -#include "exception.h" -#include "reg_constant.h" -#include "fpu_emu.h" -#include "control_w.h" -#include "poly.h" - - -#define HIPOWER 11 -static const unsigned long long lterms[HIPOWER] = -{ - 0x0000000000000000LL, /* This term done separately as 12 bytes */ - 0xf5fdeffc162c7543LL, - 0x1c6b08d704a0bfa6LL, - 0x0276556df749cc21LL, - 0x002bb0ffcf14f6b8LL, - 0x0002861225ef751cLL, - 0x00001ffcbfcd5422LL, - 0x00000162c005d5f1LL, - 0x0000000da96ccb1bLL, - 0x0000000078d1b897LL, - 0x000000000422b029LL -}; - -static const Xsig hiterm = MK_XSIG(0xb17217f7, 0xd1cf79ab, 0xc8a39194); - -/* Four slices: 0.0 : 0.25 : 0.50 : 0.75 : 1.0, - These numbers are 2^(1/4), 2^(1/2), and 2^(3/4) - */ -static const Xsig shiftterm0 = MK_XSIG(0, 0, 0); -static const Xsig shiftterm1 = MK_XSIG(0x9837f051, 0x8db8a96f, 0x46ad2318); -static const Xsig shiftterm2 = MK_XSIG(0xb504f333, 0xf9de6484, 0x597d89b3); -static const Xsig shiftterm3 = MK_XSIG(0xd744fcca, 0xd69d6af4, 0x39a68bb9); - -static const Xsig *shiftterm[] = { &shiftterm0, &shiftterm1, - &shiftterm2, &shiftterm3 }; - - -/*--- poly_2xm1() -----------------------------------------------------------+ - | Requires an argument which is TW_Valid and < 1. | - +---------------------------------------------------------------------------*/ -int poly_2xm1(FPU_REG const *arg, FPU_REG *result) -{ - long int exponent, shift; - unsigned long long Xll; - Xsig accumulator, Denom, argSignif; - - - exponent = arg->exp - EXP_BIAS; - -#ifdef PARANOID - if ( (exponent >= 0) /* Don't want a |number| >= 1.0 */ - || (arg->tag != TW_Valid) ) - { - /* Number negative, too large, or not Valid. */ - EXCEPTION(EX_INTERNAL|0x127); - return 1; - } -#endif PARANOID - - argSignif.lsw = 0; - XSIG_LL(argSignif) = Xll = significand(arg); - - if ( exponent == -1 ) - { - shift = (argSignif.msw & 0x40000000) ? 3 : 2; - /* subtract 0.5 or 0.75 */ - exponent -= 2; - XSIG_LL(argSignif) <<= 2; - Xll <<= 2; - } - else if ( exponent == -2 ) - { - shift = 1; - /* subtract 0.25 */ - exponent--; - XSIG_LL(argSignif) <<= 1; - Xll <<= 1; - } - else - shift = 0; - - if ( exponent < -2 ) - { - /* Shift the argument right by the required places. */ - if ( shrx(&Xll, -2-exponent) >= 0x80000000U ) - Xll++; /* round up */ - } - - accumulator.lsw = accumulator.midw = accumulator.msw = 0; - polynomial_Xsig(&accumulator, &Xll, lterms, HIPOWER-1); - mul_Xsig_Xsig(&accumulator, &argSignif); - shr_Xsig(&accumulator, 3); - - mul_Xsig_Xsig(&argSignif, &hiterm); /* The leading term */ - add_two_Xsig(&accumulator, &argSignif, &exponent); - - if ( shift ) - { - /* The argument is large, use the identity: - f(x+a) = f(a) * (f(x) + 1) - 1; - */ - shr_Xsig(&accumulator, - exponent); - accumulator.msw |= 0x80000000; /* add 1.0 */ - mul_Xsig_Xsig(&accumulator, shiftterm[shift]); - accumulator.msw &= 0x3fffffff; /* subtract 1.0 */ - exponent = 1; - } - - if ( arg->sign != SIGN_POS ) - { - /* The argument is negative, use the identity: - f(-x) = -f(x) / (1 + f(x)) - */ - Denom.lsw = accumulator.lsw; - XSIG_LL(Denom) = XSIG_LL(accumulator); - if ( exponent < 0 ) - shr_Xsig(&Denom, - exponent); - else if ( exponent > 0 ) - { - /* exponent must be 1 here */ - XSIG_LL(Denom) <<= 1; - if ( Denom.lsw & 0x80000000 ) - XSIG_LL(Denom) |= 1; - (Denom.lsw) <<= 1; - } - Denom.msw |= 0x80000000; /* add 1.0 */ - div_Xsig(&accumulator, &Denom, &accumulator); - } - - /* Convert to 64 bit signed-compatible */ - exponent += round_Xsig(&accumulator); - - significand(result) = XSIG_LL(accumulator); - result->tag = TW_Valid; - result->exp = exponent + EXP_BIAS; - result->sign = arg->sign; - - return 0; - -} |