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Diffstat (limited to 'src/lib/softfloat/fsincos.c')
-rwxr-xr-x | src/lib/softfloat/fsincos.c | 569 |
1 files changed, 569 insertions, 0 deletions
diff --git a/src/lib/softfloat/fsincos.c b/src/lib/softfloat/fsincos.c new file mode 100755 index 00000000000..3a0d4ccc1e0 --- /dev/null +++ b/src/lib/softfloat/fsincos.c @@ -0,0 +1,569 @@ +/*============================================================================ +This source file is an extension to the SoftFloat IEC/IEEE Floating-point +Arithmetic Package, Release 2b, written for Bochs (x86 achitecture simulator) +floating point emulation. + +THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort has +been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT TIMES +RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO PERSONS +AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ALL LOSSES, +COSTS, OR OTHER PROBLEMS THEY INCUR DUE TO THE SOFTWARE, AND WHO FURTHERMORE +EFFECTIVELY INDEMNIFY JOHN HAUSER AND THE INTERNATIONAL COMPUTER SCIENCE +INSTITUTE (possibly via similar legal warning) AGAINST ALL LOSSES, COSTS, OR +OTHER PROBLEMS INCURRED BY THEIR CUSTOMERS AND CLIENTS DUE TO THE SOFTWARE. + +Derivative works are acceptable, even for commercial purposes, so long as +(1) the source code for the derivative work includes prominent notice that +the work is derivative, and (2) the source code includes prominent notice with +these four paragraphs for those parts of this code that are retained. +=============================================================================*/ + +/*============================================================================ + * Written for Bochs (x86 achitecture simulator) by + * Stanislav Shwartsman [sshwarts at sourceforge net] + * ==========================================================================*/ + +#define FLOAT128 + +#define USE_estimateDiv128To64 +#include "mamesf.h" +#include "softfloat.h" +//#include "softfloat-specialize" +#include "fpu_constant.h" + +static const floatx80 floatx80_one = packFloatx80(0, 0x3fff, U64(0x8000000000000000)); +static const floatx80 floatx80_default_nan = packFloatx80(0, 0xffff, U64(0xffffffffffffffff)); + +#define packFloat2x128m(zHi, zLo) {(zLo), (zHi)} +#define PACK_FLOAT_128(hi,lo) packFloat2x128m(LIT64(hi),LIT64(lo)) + +#define EXP_BIAS 0x3FFF + +/*---------------------------------------------------------------------------- +| Returns the fraction bits of the extended double-precision floating-point +| value `a'. +*----------------------------------------------------------------------------*/ + +INLINE bits64 extractFloatx80Frac( floatx80 a ) +{ + + return a.low; + +} + +/*---------------------------------------------------------------------------- +| Returns the exponent bits of the extended double-precision floating-point +| value `a'. +*----------------------------------------------------------------------------*/ + +INLINE int32 extractFloatx80Exp( floatx80 a ) +{ + + return a.high & 0x7FFF; + +} + +/*---------------------------------------------------------------------------- +| Returns the sign bit of the extended double-precision floating-point value +| `a'. +*----------------------------------------------------------------------------*/ + +INLINE flag extractFloatx80Sign( floatx80 a ) +{ + + return a.high>>15; + +} + +/*---------------------------------------------------------------------------- +| Takes extended double-precision floating-point NaN `a' and returns the +| appropriate NaN result. If `a' is a signaling NaN, the invalid exception +| is raised. +*----------------------------------------------------------------------------*/ + +INLINE floatx80 propagateFloatx80NaNOneArg(floatx80 a) +{ + if (floatx80_is_signaling_nan(a)) + float_raise(float_flag_invalid); + + a.low |= U64(0xC000000000000000); + + return a; +} + +/*---------------------------------------------------------------------------- +| Normalizes the subnormal extended double-precision floating-point value +| represented by the denormalized significand `aSig'. The normalized exponent +| and significand are stored at the locations pointed to by `zExpPtr' and +| `zSigPtr', respectively. +*----------------------------------------------------------------------------*/ + +void normalizeFloatx80Subnormal(UINT64 aSig, INT32 *zExpPtr, UINT64 *zSigPtr) +{ + int shiftCount = countLeadingZeros64(aSig); + *zSigPtr = aSig<<shiftCount; + *zExpPtr = 1 - shiftCount; +} + +/* reduce trigonometric function argument using 128-bit precision + M_PI approximation */ +static UINT64 argument_reduction_kernel(UINT64 aSig0, int Exp, UINT64 *zSig0, UINT64 *zSig1) +{ + UINT64 term0, term1, term2; + UINT64 aSig1 = 0; + + shortShift128Left(aSig1, aSig0, Exp, &aSig1, &aSig0); + UINT64 q = estimateDiv128To64(aSig1, aSig0, FLOAT_PI_HI); + mul128By64To192(FLOAT_PI_HI, FLOAT_PI_LO, q, &term0, &term1, &term2); + sub128(aSig1, aSig0, term0, term1, zSig1, zSig0); + while ((INT64)(*zSig1) < 0) { + --q; + add192(*zSig1, *zSig0, term2, 0, FLOAT_PI_HI, FLOAT_PI_LO, zSig1, zSig0, &term2); + } + *zSig1 = term2; + return q; +} + +static int reduce_trig_arg(int expDiff, int &zSign, UINT64 &aSig0, UINT64 &aSig1) +{ + UINT64 term0, term1, q = 0; + + if (expDiff < 0) { + shift128Right(aSig0, 0, 1, &aSig0, &aSig1); + expDiff = 0; + } + if (expDiff > 0) { + q = argument_reduction_kernel(aSig0, expDiff, &aSig0, &aSig1); + } + else { + if (FLOAT_PI_HI <= aSig0) { + aSig0 -= FLOAT_PI_HI; + q = 1; + } + } + + shift128Right(FLOAT_PI_HI, FLOAT_PI_LO, 1, &term0, &term1); + if (! lt128(aSig0, aSig1, term0, term1)) + { + int lt = lt128(term0, term1, aSig0, aSig1); + int eq = eq128(aSig0, aSig1, term0, term1); + + if ((eq && (q & 1)) || lt) { + zSign = !zSign; + ++q; + } + if (lt) sub128(FLOAT_PI_HI, FLOAT_PI_LO, aSig0, aSig1, &aSig0, &aSig1); + } + + return (int)(q & 3); +} + +#define SIN_ARR_SIZE 11 +#define COS_ARR_SIZE 11 + +static float128 sin_arr[SIN_ARR_SIZE] = +{ + PACK_FLOAT_128(0x3fff000000000000, 0x0000000000000000), /* 1 */ + PACK_FLOAT_128(0xbffc555555555555, 0x5555555555555555), /* 3 */ + PACK_FLOAT_128(0x3ff8111111111111, 0x1111111111111111), /* 5 */ + PACK_FLOAT_128(0xbff2a01a01a01a01, 0xa01a01a01a01a01a), /* 7 */ + PACK_FLOAT_128(0x3fec71de3a556c73, 0x38faac1c88e50017), /* 9 */ + PACK_FLOAT_128(0xbfe5ae64567f544e, 0x38fe747e4b837dc7), /* 11 */ + PACK_FLOAT_128(0x3fde6124613a86d0, 0x97ca38331d23af68), /* 13 */ + PACK_FLOAT_128(0xbfd6ae7f3e733b81, 0xf11d8656b0ee8cb0), /* 15 */ + PACK_FLOAT_128(0x3fce952c77030ad4, 0xa6b2605197771b00), /* 17 */ + PACK_FLOAT_128(0xbfc62f49b4681415, 0x724ca1ec3b7b9675), /* 19 */ + PACK_FLOAT_128(0x3fbd71b8ef6dcf57, 0x18bef146fcee6e45) /* 21 */ +}; + +static float128 cos_arr[COS_ARR_SIZE] = +{ + PACK_FLOAT_128(0x3fff000000000000, 0x0000000000000000), /* 0 */ + PACK_FLOAT_128(0xbffe000000000000, 0x0000000000000000), /* 2 */ + PACK_FLOAT_128(0x3ffa555555555555, 0x5555555555555555), /* 4 */ + PACK_FLOAT_128(0xbff56c16c16c16c1, 0x6c16c16c16c16c17), /* 6 */ + PACK_FLOAT_128(0x3fefa01a01a01a01, 0xa01a01a01a01a01a), /* 8 */ + PACK_FLOAT_128(0xbfe927e4fb7789f5, 0xc72ef016d3ea6679), /* 10 */ + PACK_FLOAT_128(0x3fe21eed8eff8d89, 0x7b544da987acfe85), /* 12 */ + PACK_FLOAT_128(0xbfda93974a8c07c9, 0xd20badf145dfa3e5), /* 14 */ + PACK_FLOAT_128(0x3fd2ae7f3e733b81, 0xf11d8656b0ee8cb0), /* 16 */ + PACK_FLOAT_128(0xbfca6827863b97d9, 0x77bb004886a2c2ab), /* 18 */ + PACK_FLOAT_128(0x3fc1e542ba402022, 0x507a9cad2bf8f0bb) /* 20 */ +}; + +extern float128 OddPoly (float128 x, float128 *arr, unsigned n); + +/* 0 <= x <= pi/4 */ +INLINE float128 poly_sin(float128 x) +{ + // 3 5 7 9 11 13 15 + // x x x x x x x + // sin (x) ~ x - --- + --- - --- + --- - ---- + ---- - ---- = + // 3! 5! 7! 9! 11! 13! 15! + // + // 2 4 6 8 10 12 14 + // x x x x x x x + // = x * [ 1 - --- + --- - --- + --- - ---- + ---- - ---- ] = + // 3! 5! 7! 9! 11! 13! 15! + // + // 3 3 + // -- 4k -- 4k+2 + // p(x) = > C * x > 0 q(x) = > C * x < 0 + // -- 2k -- 2k+1 + // k=0 k=0 + // + // 2 + // sin(x) ~ x * [ p(x) + x * q(x) ] + // + + return OddPoly(x, sin_arr, SIN_ARR_SIZE); +} + +extern float128 EvenPoly(float128 x, float128 *arr, unsigned n); + +/* 0 <= x <= pi/4 */ +INLINE float128 poly_cos(float128 x) +{ + // 2 4 6 8 10 12 14 + // x x x x x x x + // cos (x) ~ 1 - --- + --- - --- + --- - ---- + ---- - ---- + // 2! 4! 6! 8! 10! 12! 14! + // + // 3 3 + // -- 4k -- 4k+2 + // p(x) = > C * x > 0 q(x) = > C * x < 0 + // -- 2k -- 2k+1 + // k=0 k=0 + // + // 2 + // cos(x) ~ [ p(x) + x * q(x) ] + // + + return EvenPoly(x, cos_arr, COS_ARR_SIZE); +} + +INLINE void sincos_invalid(floatx80 *sin_a, floatx80 *cos_a, floatx80 a) +{ + if (sin_a) *sin_a = a; + if (cos_a) *cos_a = a; +} + +INLINE void sincos_tiny_argument(floatx80 *sin_a, floatx80 *cos_a, floatx80 a) +{ + if (sin_a) *sin_a = a; + if (cos_a) *cos_a = floatx80_one; +} + +static floatx80 sincos_approximation(int neg, float128 r, UINT64 quotient) +{ + if (quotient & 0x1) { + r = poly_cos(r); + neg = 0; + } else { + r = poly_sin(r); + } + + floatx80 result = float128_to_floatx80(r); + if (quotient & 0x2) + neg = ! neg; + + if (neg) + floatx80_chs(result); + + return result; +} + +// ================================================= +// SFFSINCOS Compute sin(x) and cos(x) +// ================================================= + +// +// Uses the following identities: +// ---------------------------------------------------------- +// +// sin(-x) = -sin(x) +// cos(-x) = cos(x) +// +// sin(x+y) = sin(x)*cos(y)+cos(x)*sin(y) +// cos(x+y) = sin(x)*sin(y)+cos(x)*cos(y) +// +// sin(x+ pi/2) = cos(x) +// sin(x+ pi) = -sin(x) +// sin(x+3pi/2) = -cos(x) +// sin(x+2pi) = sin(x) +// + +int sf_fsincos(floatx80 a, floatx80 *sin_a, floatx80 *cos_a) +{ + UINT64 aSig0, aSig1 = 0; + INT32 aExp, zExp, expDiff; + int aSign, zSign; + int q = 0; + + aSig0 = extractFloatx80Frac(a); + aExp = extractFloatx80Exp(a); + aSign = extractFloatx80Sign(a); + + /* invalid argument */ + if (aExp == 0x7FFF) { + if ((UINT64) (aSig0<<1)) { + sincos_invalid(sin_a, cos_a, propagateFloatx80NaNOneArg(a)); + return 0; + } + + float_raise(float_flag_invalid); + sincos_invalid(sin_a, cos_a, floatx80_default_nan); + return 0; + } + + if (aExp == 0) { + if (aSig0 == 0) { + sincos_tiny_argument(sin_a, cos_a, a); + return 0; + } + +// float_raise(float_flag_denormal); + + /* handle pseudo denormals */ + if (! (aSig0 & U64(0x8000000000000000))) + { + float_raise(float_flag_inexact); + if (sin_a) + float_raise(float_flag_underflow); + sincos_tiny_argument(sin_a, cos_a, a); + return 0; + } + + normalizeFloatx80Subnormal(aSig0, &aExp, &aSig0); + } + + zSign = aSign; + zExp = EXP_BIAS; + expDiff = aExp - zExp; + + /* argument is out-of-range */ + if (expDiff >= 63) + return -1; + + float_raise(float_flag_inexact); + + if (expDiff < -1) { // doesn't require reduction + if (expDiff <= -68) { + a = packFloatx80(aSign, aExp, aSig0); + sincos_tiny_argument(sin_a, cos_a, a); + return 0; + } + zExp = aExp; + } + else { + q = reduce_trig_arg(expDiff, zSign, aSig0, aSig1); + } + + /* **************************** */ + /* argument reduction completed */ + /* **************************** */ + + /* using float128 for approximation */ + float128 r = normalizeRoundAndPackFloat128(0, zExp-0x10, aSig0, aSig1); + + if (aSign) q = -q; + if (sin_a) *sin_a = sincos_approximation(zSign, r, q); + if (cos_a) *cos_a = sincos_approximation(zSign, r, q+1); + + return 0; +} + +int floatx80_fsin(floatx80 &a) +{ + return sf_fsincos(a, &a, 0); +} + +int floatx80_fcos(floatx80 &a) +{ + return sf_fsincos(a, 0, &a); +} + +// ================================================= +// FPTAN Compute tan(x) +// ================================================= + +// +// Uses the following identities: +// +// 1. ---------------------------------------------------------- +// +// sin(-x) = -sin(x) +// cos(-x) = cos(x) +// +// sin(x+y) = sin(x)*cos(y)+cos(x)*sin(y) +// cos(x+y) = sin(x)*sin(y)+cos(x)*cos(y) +// +// sin(x+ pi/2) = cos(x) +// sin(x+ pi) = -sin(x) +// sin(x+3pi/2) = -cos(x) +// sin(x+2pi) = sin(x) +// +// 2. ---------------------------------------------------------- +// +// sin(x) +// tan(x) = ------ +// cos(x) +// + +int floatx80_ftan(floatx80 &a) +{ + UINT64 aSig0, aSig1 = 0; + INT32 aExp, zExp, expDiff; + int aSign, zSign; + int q = 0; + + aSig0 = extractFloatx80Frac(a); + aExp = extractFloatx80Exp(a); + aSign = extractFloatx80Sign(a); + + /* invalid argument */ + if (aExp == 0x7FFF) { + if ((UINT64) (aSig0<<1)) + { + a = propagateFloatx80NaNOneArg(a); + return 0; + } + + float_raise(float_flag_invalid); + a = floatx80_default_nan; + return 0; + } + + if (aExp == 0) { + if (aSig0 == 0) return 0; +// float_raise(float_flag_denormal); + /* handle pseudo denormals */ + if (! (aSig0 & U64(0x8000000000000000))) + { + float_raise(float_flag_inexact | float_flag_underflow); + return 0; + } + normalizeFloatx80Subnormal(aSig0, &aExp, &aSig0); + } + + zSign = aSign; + zExp = EXP_BIAS; + expDiff = aExp - zExp; + + /* argument is out-of-range */ + if (expDiff >= 63) + return -1; + + float_raise(float_flag_inexact); + + if (expDiff < -1) { // doesn't require reduction + if (expDiff <= -68) { + a = packFloatx80(aSign, aExp, aSig0); + return 0; + } + zExp = aExp; + } + else { + q = reduce_trig_arg(expDiff, zSign, aSig0, aSig1); + } + + /* **************************** */ + /* argument reduction completed */ + /* **************************** */ + + /* using float128 for approximation */ + float128 r = normalizeRoundAndPackFloat128(0, zExp-0x10, aSig0, aSig1); + + float128 sin_r = poly_sin(r); + float128 cos_r = poly_cos(r); + + if (q & 0x1) { + r = float128_div(cos_r, sin_r); + zSign = ! zSign; + } else { + r = float128_div(sin_r, cos_r); + } + + a = float128_to_floatx80(r); + if (zSign) + floatx80_chs(a); + + return 0; +} + +// 2 3 4 n +// f(x) ~ C + (C * x) + (C * x) + (C * x) + (C * x) + ... + (C * x) +// 0 1 2 3 4 n +// +// -- 2k -- 2k+1 +// p(x) = > C * x q(x) = > C * x +// -- 2k -- 2k+1 +// +// f(x) ~ [ p(x) + x * q(x) ] +// + +float128 EvalPoly(float128 x, float128 *arr, unsigned n) +{ + float128 x2 = float128_mul(x, x); + unsigned i; + + assert(n > 1); + + float128 r1 = arr[--n]; + i = n; + while(i >= 2) { + r1 = float128_mul(r1, x2); + i -= 2; + r1 = float128_add(r1, arr[i]); + } + if (i) r1 = float128_mul(r1, x); + + float128 r2 = arr[--n]; + i = n; + while(i >= 2) { + r2 = float128_mul(r2, x2); + i -= 2; + r2 = float128_add(r2, arr[i]); + } + if (i) r2 = float128_mul(r2, x); + + return float128_add(r1, r2); +} + +// 2 4 6 8 2n +// f(x) ~ C + (C * x) + (C * x) + (C * x) + (C * x) + ... + (C * x) +// 0 1 2 3 4 n +// +// -- 4k -- 4k+2 +// p(x) = > C * x q(x) = > C * x +// -- 2k -- 2k+1 +// +// 2 +// f(x) ~ [ p(x) + x * q(x) ] +// + +float128 EvenPoly(float128 x, float128 *arr, unsigned n) +{ + return EvalPoly(float128_mul(x, x), arr, n); +} + +// 3 5 7 9 2n+1 +// f(x) ~ (C * x) + (C * x) + (C * x) + (C * x) + (C * x) + ... + (C * x) +// 0 1 2 3 4 n +// 2 4 6 8 2n +// = x * [ C + (C * x) + (C * x) + (C * x) + (C * x) + ... + (C * x) +// 0 1 2 3 4 n +// +// -- 4k -- 4k+2 +// p(x) = > C * x q(x) = > C * x +// -- 2k -- 2k+1 +// +// 2 +// f(x) ~ x * [ p(x) + x * q(x) ] +// + +float128 OddPoly(float128 x, float128 *arr, unsigned n) +{ + return float128_mul(x, EvenPoly(x, arr, n)); +} + |