/*--- poly_tan() ------------------------------------------------------------+
| |
+---------------------------------------------------------------------------*/
void poly_tan(FPU_REG *st0_ptr)
{
long int exponent;
int invert;
Xsig argSq, argSqSq, accumulatoro, accumulatore, accum,
argSignif, fix_up;
unsigned long adj;
exponent = exponent(st0_ptr);
#ifdef PARANOID
if ( signnegative(st0_ptr) ) /* Can't hack a number < 0.0 */
{ arith_invalid(0); return; } /* Need a positive number */
#endif PARANOID
/* Split the problem into two domains, smaller and larger than pi/4 */
if ( (exponent == 0) || ((exponent == -1) && (st0_ptr->sigh > 0xc90fdaa2)) )
{
/* The argument is greater than (approx) pi/4 */
invert = 1;
accum.lsw = 0;
XSIG_LL(accum) = significand(st0_ptr);
if ( exponent == 0 )
{
/* The argument is >= 1.0 */
/* Put the binary point at the left. */
XSIG_LL(accum) <<= 1;
}
/* pi/2 in hex is: 1.921fb54442d18469 898CC51701B839A2 52049C1 */
XSIG_LL(accum) = 0x921fb54442d18469LL - XSIG_LL(accum);
/* This is a special case which arises due to rounding. */
if ( XSIG_LL(accum) == 0xffffffffffffffffLL )
{
FPU_settag0(TAG_Valid);
significand(st0_ptr) = 0x8a51e04daabda360LL;
setexponent16(st0_ptr, (0x41 + EXTENDED_Ebias) | SIGN_Negative);
return;
}
argSignif.lsw = accum.lsw;
XSIG_LL(argSignif) = XSIG_LL(accum);
exponent = -1 + norm_Xsig(&argSignif);
}
else
{
invert = 0;
argSignif.lsw = 0;
XSIG_LL(accum) = XSIG_LL(argSignif) = significand(st0_ptr);
if ( exponent < -1 )
{
/* shift the argument right by the required places */
if ( FPU_shrx(&XSIG_LL(accum), -1-exponent) >= 0x80000000U )
XSIG_LL(accum) ++; /* round up */
}
}
XSIG_LL(argSq) = XSIG_LL(accum); argSq.lsw = accum.lsw;
mul_Xsig_Xsig(&argSq, &argSq);
XSIG_LL(argSqSq) = XSIG_LL(argSq); argSqSq.lsw = argSq.lsw;
mul_Xsig_Xsig(&argSqSq, &argSqSq);
/* Compute the negative terms for the numerator polynomial */
accumulatoro.msw = accumulatoro.midw = accumulatoro.lsw = 0;
polynomial_Xsig(&accumulatoro, &XSIG_LL(argSqSq), oddnegterm, HiPOWERon-1);
mul_Xsig_Xsig(&accumulatoro, &argSq);
negate_Xsig(&accumulatoro);
/* Add the positive terms */
polynomial_Xsig(&accumulatoro, &XSIG_LL(argSqSq), oddplterm, HiPOWERop-1);
/* Compute the positive terms for the denominator polynomial */
accumulatore.msw = accumulatore.midw = accumulatore.lsw = 0;
polynomial_Xsig(&accumulatore, &XSIG_LL(argSqSq), evenplterm, HiPOWERep-1);
mul_Xsig_Xsig(&accumulatore, &argSq);
negate_Xsig(&accumulatore);
/* Add the negative terms */
polynomial_Xsig(&accumulatore, &XSIG_LL(argSqSq), evennegterm, HiPOWERen-1);
/* Multiply by arg^2 */
mul64_Xsig(&accumulatore, &XSIG_LL(argSignif));
mul64_Xsig(&accumulatore, &XSIG_LL(argSignif));
/* de-normalize and divide by 2 */
shr_Xsig(&accumulatore, -2*(1+exponent) + 1);
negate_Xsig(&accumulatore); /* This does 1 - accumulator */
/* Now find the ratio. */
if ( accumulatore.msw == 0 )
{
/* accumulatoro must contain 1.0 here, (actually, 0) but it
really doesn't matter what value we use because it will
have negligible effect in later calculations
*/
XSIG_LL(accum) = 0x8000000000000000LL;
accum.lsw = 0;
}
else
{
div_Xsig(&accumulatoro, &accumulatore, &accum);
}
/* Multiply by 1/3 * arg^3 */
mul64_Xsig(&accum, &XSIG_LL(argSignif));
mul64_Xsig(&accum, &XSIG_LL(argSignif));
mul64_Xsig(&accum, &XSIG_LL(argSignif));
mul64_Xsig(&accum, &twothirds);
shr_Xsig(&accum, -2*(exponent+1));
/* tan(arg) = arg + accum */
add_two_Xsig(&accum, &argSignif, &exponent);
if ( invert )
{
/* We now have the value of tan(pi_2 - arg) where pi_2 is an
approximation for pi/2
*/
/* The next step is to fix the answer to compensate for the
error due to the approximation used for pi/2
*/
/* This is (approx) delta, the error in our approx for pi/2
(see above). It has an exponent of -65
*/
XSIG_LL(fix_up) = 0x898cc51701b839a2LL;
fix_up.lsw = 0;
if ( exponent == 0 )
adj = 0xffffffff; /* We want approx 1.0 here, but
this is close enough. */
else if ( exponent > -30 )
{
adj = accum.msw >> -(exponent+1); /* tan */
adj = mul_32_32(adj, adj); /* tan^2 */
}
else
(see above). It has an exponent of -65
*/
XSIG_LL(fix_up) = 0x898cc51701b839a2LL;
fix_up.lsw = 0;
if ( exponent == 0 )
adj = 0xffffffff; /* We want approx 1.0 here, but
this is close enough. */
else if ( exponent > -30 )
{
adj = accum.msw >> -(exponent+1); /* tan */
adj = mul_32_32(adj, adj); /* tan^2 */
}
else
adj = 0;
adj = mul_32_32(0x898cc517, adj); /* delta * tan^2 */
fix_up.msw += adj;
if ( !(fix_up.msw & 0x80000000) ) /* did fix_up overflow ? */
{
/* Yes, we need to add an msb */
shr_Xsig(&fix_up, 1);
fix_up.msw |= 0x80000000;
shr_Xsig(&fix_up, 64 + exponent);
}
else
shr_Xsig(&fix_up, 65 + exponent);
add_two_Xsig(&accum, &fix_up, &exponent);
/* accum now contains tan(pi/2 - arg).
void poly_sine(FPU_REG *st0_ptr)
{
int exponent, echange;
Xsig accumulator, argSqrd, argTo4;
unsigned long fix_up, adj;
unsigned long long fixed_arg;
FPU_REG result;
exponent = exponent(st0_ptr);
accumulator.lsw = accumulator.midw = accumulator.msw = 0;
if ((exponent < -1)
|| ((exponent == -1) && (st0_ptr->sigh <= 0xe21240aa))) {
argSqrd.msw = st0_ptr->sigh;
argSqrd.midw = st0_ptr->sigl;
argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &significand(st0_ptr));
shr_Xsig(&argSqrd, 2 * (-1 - exponent));
argTo4.msw = argSqrd.msw;
argTo4.midw = argSqrd.midw;
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_l,
N_COEFF_N - 1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_l,
N_COEFF_P - 1);
shr_Xsig(&accumulator, 2);
accumulator.msw |= 0x80000000;
mul64_Xsig(&accumulator, &significand(st0_ptr));
mul64_Xsig(&accumulator, &significand(st0_ptr));
mul64_Xsig(&accumulator, &significand(st0_ptr));
exponent = 3 * exponent;
shr_Xsig(&accumulator, exponent(st0_ptr) - exponent);
negate_Xsig(&accumulator);
XSIG_LL(accumulator) += significand(st0_ptr);
echange = round_Xsig(&accumulator);
setexponentpos(&result, exponent(st0_ptr) + echange);
} else {
fixed_arg = significand(st0_ptr);
if (exponent == 0) {
fixed_arg <<= 1;
}
fixed_arg = 0x921fb54442d18469LL - fixed_arg;
if (fixed_arg == 0xffffffffffffffffLL)
fixed_arg = 0;
XSIG_LL(argSqrd) = fixed_arg;
argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &fixed_arg);
XSIG_LL(argTo4) = XSIG_LL(argSqrd);
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_h,
N_COEFF_NH - 1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_h,
N_COEFF_PH - 1);
negate_Xsig(&accumulator);
mul64_Xsig(&accumulator, &fixed_arg);
mul64_Xsig(&accumulator, &fixed_arg);
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSqrd);
shr_Xsig(&accumulator, 1);
accumulator.lsw |= 1;
negate_Xsig(&accumulator);
fix_up = 0x898cc517;
if (argSqrd.msw & 0xffc00000) {
fix_up -= mul_32_32(0x898cc517, argSqrd.msw) / 6;
}
fix_up = mul_32_32(fix_up, LL_MSW(fixed_arg));
adj = accumulator.lsw;
accumulator.lsw -= fix_up;
if (accumulator.lsw > adj)
XSIG_LL(accumulator)--;
echange = round_Xsig(&accumulator);
setexponentpos(&result, echange - 1);
}
significand(&result) = XSIG_LL(accumulator);
setsign(&result, getsign(st0_ptr));
FPU_copy_to_reg0(&result, TAG_Valid);
#ifdef PARANOID
if ((exponent(&result) >= 0)
&& (significand(&result) > 0x8000000000000000LL)) {
EXCEPTION(EX_INTERNAL | 0x150);
}
#endif
}
void poly_cos(FPU_REG *st0_ptr)
{
FPU_REG result;
long int exponent, exp2, echange;
Xsig accumulator, argSqrd, fix_up, argTo4;
unsigned long long fixed_arg;
#ifdef PARANOID
if ((exponent(st0_ptr) > 0)
|| ((exponent(st0_ptr) == 0)
&& (significand(st0_ptr) > 0xc90fdaa22168c234LL))) {
EXCEPTION(EX_Invalid);
FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
return;
}
#endif
exponent = exponent(st0_ptr);
accumulator.lsw = accumulator.midw = accumulator.msw = 0;
if ((exponent < -1)
|| ((exponent == -1) && (st0_ptr->sigh <= 0xb00d6f54))) {
argSqrd.msw = st0_ptr->sigh;
argSqrd.midw = st0_ptr->sigl;
argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &significand(st0_ptr));
if (exponent < -1) {
shr_Xsig(&argSqrd, 2 * (-1 - exponent));
}
argTo4.msw = argSqrd.msw;
argTo4.midw = argSqrd.midw;
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_h,
N_COEFF_NH - 1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_h,
N_COEFF_PH - 1);
negate_Xsig(&accumulator);
mul64_Xsig(&accumulator, &significand(st0_ptr));
mul64_Xsig(&accumulator, &significand(st0_ptr));
shr_Xsig(&accumulator, -2 * (1 + exponent));
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSqrd);
shr_Xsig(&accumulator, 1);
negate_Xsig(&accumulator);
if (accumulator.lsw & 0x80000000)
XSIG_LL(accumulator)++;
if (accumulator.msw == 0) {
FPU_copy_to_reg0(&CONST_1, TAG_Valid);
return;
} else {
significand(&result) = XSIG_LL(accumulator);
setexponentpos(&result, -1);
}
} else {
fixed_arg = significand(st0_ptr);
if (exponent == 0) {
fixed_arg <<= 1;
}
fixed_arg = 0x921fb54442d18469LL - fixed_arg;
if (fixed_arg == 0xffffffffffffffffLL)
fixed_arg = 0;
exponent = -1;
exp2 = -1;
if (!(LL_MSW(fixed_arg) & 0xffff0000)) {
fixed_arg <<= 16;
exponent -= 16;
exp2 -= 16;
}
XSIG_LL(argSqrd) = fixed_arg;
argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &fixed_arg);
if (exponent < -1) {
shr_Xsig(&argSqrd, 2 * (-1 - exponent));
}
argTo4.msw = argSqrd.msw;
argTo4.midw = argSqrd.midw;
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_l,
N_COEFF_N - 1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_l,
N_COEFF_P - 1);
shr_Xsig(&accumulator, 2);
accumulator.msw |= 0x80000000;
mul64_Xsig(&accumulator, &fixed_arg);
mul64_Xsig(&accumulator, &fixed_arg);
mul64_Xsig(&accumulator, &fixed_arg);
exponent = 3 * exponent;
shr_Xsig(&accumulator, exp2 - exponent);
negate_Xsig(&accumulator);
XSIG_LL(accumulator) += fixed_arg;
XSIG_LL(fix_up) = 0x898cc51701b839a2ll;
fix_up.lsw = 0;
if (argSqrd.msw & 0xffc00000) {
fix_up.msw -= mul_32_32(0x898cc517, argSqrd.msw) / 2;
fix_up.msw += mul_32_32(0x898cc517, argTo4.msw) / 24;
}
exp2 += norm_Xsig(&accumulator);
shr_Xsig(&accumulator, 1);
exp2++;
shr_Xsig(&fix_up, 65 + exp2);
add_Xsig_Xsig(&accumulator, &fix_up);
echange = round_Xsig(&accumulator);
setexponentpos(&result, exp2 + echange);
significand(&result) = XSIG_LL(accumulator);
}
FPU_copy_to_reg0(&result, TAG_Valid);
#ifdef PARANOID
if ((exponent(&result) >= 0)
&& (significand(&result) > 0x8000000000000000LL)) {
EXCEPTION(EX_INTERNAL | 0x151);
}
#endif
}
/*--- poly_sine() -----------------------------------------------------------+
| |
+---------------------------------------------------------------------------*/
void poly_sine(FPU_REG const *arg, FPU_REG *result)
{
int exponent, echange;
Xsig accumulator, argSqrd, argTo4;
unsigned long fix_up, adj;
unsigned long long fixed_arg;
#ifdef PARANOID
if ( arg->tag == TW_Zero )
{
/* Return 0.0 */
reg_move(&CONST_Z, result);
return;
}
#endif PARANOID
exponent = arg->exp - EXP_BIAS;
accumulator.lsw = accumulator.midw = accumulator.msw = 0;
/* Split into two ranges, for arguments below and above 1.0 */
/* The boundary between upper and lower is approx 0.88309101259 */
if ( (exponent < -1) || ((exponent == -1) && (arg->sigh <= 0xe21240aa)) )
{
/* The argument is <= 0.88309101259 */
argSqrd.msw = arg->sigh; argSqrd.midw = arg->sigl; argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &significand(arg));
shr_Xsig(&argSqrd, 2*(-1-exponent));
argTo4.msw = argSqrd.msw; argTo4.midw = argSqrd.midw;
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_l,
N_COEFF_N-1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_l,
N_COEFF_P-1);
shr_Xsig(&accumulator, 2); /* Divide by four */
accumulator.msw |= 0x80000000; /* Add 1.0 */
mul64_Xsig(&accumulator, &significand(arg));
mul64_Xsig(&accumulator, &significand(arg));
mul64_Xsig(&accumulator, &significand(arg));
/* Divide by four, FPU_REG compatible, etc */
exponent = 3*exponent + EXP_BIAS;
/* The minimum exponent difference is 3 */
shr_Xsig(&accumulator, arg->exp - exponent);
negate_Xsig(&accumulator);
XSIG_LL(accumulator) += significand(arg);
echange = round_Xsig(&accumulator);
result->exp = arg->exp + echange;
}
else
{
/* The argument is > 0.88309101259 */
/* We use sin(arg) = cos(pi/2-arg) */
fixed_arg = significand(arg);
if ( exponent == 0 )
{
/* The argument is >= 1.0 */
/* Put the binary point at the left. */
fixed_arg <<= 1;
}
/* pi/2 in hex is: 1.921fb54442d18469 898CC51701B839A2 52049C1 */
fixed_arg = 0x921fb54442d18469LL - fixed_arg;
XSIG_LL(argSqrd) = fixed_arg; argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &fixed_arg);
XSIG_LL(argTo4) = XSIG_LL(argSqrd); argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_h,
N_COEFF_NH-1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_h,
N_COEFF_PH-1);
negate_Xsig(&accumulator);
mul64_Xsig(&accumulator, &fixed_arg);
mul64_Xsig(&accumulator, &fixed_arg);
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSqrd);
shr_Xsig(&accumulator, 1);
accumulator.lsw |= 1; /* A zero accumulator here would cause problems */
negate_Xsig(&accumulator);
/* The basic computation is complete. Now fix the answer to
compensate for the error due to the approximation used for
pi/2
*/
/* This has an exponent of -65 */
fix_up = 0x898cc517;
/* The fix-up needs to be improved for larger args */
if ( argSqrd.msw & 0xffc00000 )
{
/* Get about 32 bit precision in these: */
mul_32_32(0x898cc517, argSqrd.msw, &adj);
fix_up -= adj/6;
}
mul_32_32(fix_up, LL_MSW(fixed_arg), &fix_up);
adj = accumulator.lsw; /* temp save */
accumulator.lsw -= fix_up;
if ( accumulator.lsw > adj )
XSIG_LL(accumulator) --;
echange = round_Xsig(&accumulator);
result->exp = EXP_BIAS - 1 + echange;
}
significand(result) = XSIG_LL(accumulator);
result->tag = TW_Valid;
result->sign = arg->sign;
#ifdef PARANOID
if ( (result->exp >= EXP_BIAS)
&& (significand(result) > 0x8000000000000000LL) )
{
EXCEPTION(EX_INTERNAL|0x150);
}
#endif PARANOID
}
/*--- poly_cos() ------------------------------------------------------------+
| |
+---------------------------------------------------------------------------*/
void poly_cos(FPU_REG const *arg, FPU_REG *result)
{
long int exponent, exp2, echange;
Xsig accumulator, argSqrd, fix_up, argTo4;
unsigned long adj;
unsigned long long fixed_arg;
#ifdef PARANOID
if ( arg->tag == TW_Zero )
{
/* Return 1.0 */
reg_move(&CONST_1, result);
return;
}
if ( (arg->exp > EXP_BIAS)
|| ((arg->exp == EXP_BIAS)
&& (significand(arg) > 0xc90fdaa22168c234LL)) )
{
EXCEPTION(EX_Invalid);
reg_move(&CONST_QNaN, result);
return;
}
#endif PARANOID
exponent = arg->exp - EXP_BIAS;
accumulator.lsw = accumulator.midw = accumulator.msw = 0;
if ( (exponent < -1) || ((exponent == -1) && (arg->sigh <= 0xb00d6f54)) )
{
/* arg is < 0.687705 */
argSqrd.msw = arg->sigh; argSqrd.midw = arg->sigl; argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &significand(arg));
if ( exponent < -1 )
{
/* shift the argument right by the required places */
shr_Xsig(&argSqrd, 2*(-1-exponent));
}
argTo4.msw = argSqrd.msw; argTo4.midw = argSqrd.midw;
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_h,
N_COEFF_NH-1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_h,
N_COEFF_PH-1);
negate_Xsig(&accumulator);
mul64_Xsig(&accumulator, &significand(arg));
mul64_Xsig(&accumulator, &significand(arg));
shr_Xsig(&accumulator, -2*(1+exponent));
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSqrd);
shr_Xsig(&accumulator, 1);
/* It doesn't matter if accumulator is all zero here, the
following code will work ok */
negate_Xsig(&accumulator);
if ( accumulator.lsw & 0x80000000 )
XSIG_LL(accumulator) ++;
if ( accumulator.msw == 0 )
{
/* The result is 1.0 */
reg_move(&CONST_1, result);
}
else
{
significand(result) = XSIG_LL(accumulator);
/* will be a valid positive nr with expon = -1 */
*(short *)&(result->sign) = 0;
result->exp = EXP_BIAS - 1;
}
}
else
{
fixed_arg = significand(arg);
if ( exponent == 0 )
{
/* The argument is >= 1.0 */
/* Put the binary point at the left. */
fixed_arg <<= 1;
}
/* pi/2 in hex is: 1.921fb54442d18469 898CC51701B839A2 52049C1 */
fixed_arg = 0x921fb54442d18469LL - fixed_arg;
exponent = -1;
exp2 = -1;
/* A shift is needed here only for a narrow range of arguments,
i.e. for fixed_arg approx 2^-32, but we pick up more... */
if ( !(LL_MSW(fixed_arg) & 0xffff0000) )
{
fixed_arg <<= 16;
exponent -= 16;
exp2 -= 16;
}
XSIG_LL(argSqrd) = fixed_arg; argSqrd.lsw = 0;
mul64_Xsig(&argSqrd, &fixed_arg);
if ( exponent < -1 )
{
/* shift the argument right by the required places */
shr_Xsig(&argSqrd, 2*(-1-exponent));
}
argTo4.msw = argSqrd.msw; argTo4.midw = argSqrd.midw;
argTo4.lsw = argSqrd.lsw;
mul_Xsig_Xsig(&argTo4, &argTo4);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), neg_terms_l,
N_COEFF_N-1);
mul_Xsig_Xsig(&accumulator, &argSqrd);
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argTo4), pos_terms_l,
N_COEFF_P-1);
shr_Xsig(&accumulator, 2); /* Divide by four */
accumulator.msw |= 0x80000000; /* Add 1.0 */
mul64_Xsig(&accumulator, &fixed_arg);
mul64_Xsig(&accumulator, &fixed_arg);
mul64_Xsig(&accumulator, &fixed_arg);
/* Divide by four, FPU_REG compatible, etc */
exponent = 3*exponent;
/* The minimum exponent difference is 3 */
shr_Xsig(&accumulator, exp2 - exponent);
negate_Xsig(&accumulator);
XSIG_LL(accumulator) += fixed_arg;
/* The basic computation is complete. Now fix the answer to
compensate for the error due to the approximation used for
pi/2
*/
/* This has an exponent of -65 */
XSIG_LL(fix_up) = 0x898cc51701b839a2ll;
fix_up.lsw = 0;
/* The fix-up needs to be improved for larger args */
if ( argSqrd.msw & 0xffc00000 )
{
/* Get about 32 bit precision in these: */
mul_32_32(0x898cc517, argSqrd.msw, &adj);
fix_up.msw -= adj/2;
mul_32_32(0x898cc517, argTo4.msw, &adj);
fix_up.msw += adj/24;
}
exp2 += norm_Xsig(&accumulator);
shr_Xsig(&accumulator, 1); /* Prevent overflow */
exp2++;
shr_Xsig(&fix_up, 65 + exp2);
add_Xsig_Xsig(&accumulator, &fix_up);
echange = round_Xsig(&accumulator);
result->exp = exp2 + EXP_BIAS + echange;
*(short *)&(result->sign) = 0; /* Is a valid positive nr */
significand(result) = XSIG_LL(accumulator);
}
#ifdef PARANOID
if ( (result->exp >= EXP_BIAS)
&& (significand(result) > 0x8000000000000000LL) )
{
EXCEPTION(EX_INTERNAL|0x151);
}
#endif PARANOID
}
