/*--- poly_atan() -----------------------------------------------------------+
| |
+---------------------------------------------------------------------------*/
void poly_atan(FPU_REG *st0_ptr, u_char st0_tag,
FPU_REG *st1_ptr, u_char st1_tag)
{
u_char transformed, inverted,
sign1, sign2;
int exponent;
long int dummy_exp;
Xsig accumulator, Numer, Denom, accumulatore, argSignif,
argSq, argSqSq;
u_char tag;
sign1 = getsign(st0_ptr);
sign2 = getsign(st1_ptr);
if ( st0_tag == TAG_Valid )
{
exponent = exponent(st0_ptr);
}
else
{
/* This gives non-compatible stack contents... */
FPU_to_exp16(st0_ptr, st0_ptr);
exponent = exponent16(st0_ptr);
}
if ( st1_tag == TAG_Valid )
{
exponent -= exponent(st1_ptr);
}
else
{
/* This gives non-compatible stack contents... */
FPU_to_exp16(st1_ptr, st1_ptr);
exponent -= exponent16(st1_ptr);
}
if ( (exponent < 0) || ((exponent == 0) &&
((st0_ptr->sigh < st1_ptr->sigh) ||
((st0_ptr->sigh == st1_ptr->sigh) &&
(st0_ptr->sigl < st1_ptr->sigl))) ) )
{
inverted = 1;
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = significand(st0_ptr);
XSIG_LL(Denom) = significand(st1_ptr);
}
else
{
inverted = 0;
exponent = -exponent;
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = significand(st1_ptr);
XSIG_LL(Denom) = significand(st0_ptr);
}
div_Xsig(&Numer, &Denom, &argSignif);
exponent += norm_Xsig(&argSignif);
if ( (exponent >= -1)
|| ((exponent == -2) && (argSignif.msw > 0xd413ccd0)) )
{
/* The argument is greater than sqrt(2)-1 (=0.414213562...) */
/* Convert the argument by an identity for atan */
transformed = 1;
if ( exponent >= 0 )
{
#ifdef PARANOID
if ( !( (exponent == 0) &&
(argSignif.lsw == 0) && (argSignif.midw == 0) &&
(argSignif.msw == 0x80000000) ) )
{
EXCEPTION(EX_INTERNAL|0x104); /* There must be a logic error */
return;
}
#endif /* PARANOID */
argSignif.msw = 0; /* Make the transformed arg -> 0.0 */
}
else
{
Numer.lsw = Denom.lsw = argSignif.lsw;
XSIG_LL(Numer) = XSIG_LL(Denom) = XSIG_LL(argSignif);
if ( exponent < -1 )
shr_Xsig(&Numer, -1-exponent);
negate_Xsig(&Numer);
shr_Xsig(&Denom, -exponent);
Denom.msw |= 0x80000000;
div_Xsig(&Numer, &Denom, &argSignif);
exponent = -1 + norm_Xsig(&argSignif);
}
}
else
{
transformed = 0;
}
argSq.lsw = argSignif.lsw; argSq.midw = argSignif.midw;
argSq.msw = argSignif.msw;
mul_Xsig_Xsig(&argSq, &argSq);
argSqSq.lsw = argSq.lsw; argSqSq.midw = argSq.midw; argSqSq.msw = argSq.msw;
mul_Xsig_Xsig(&argSqSq, &argSqSq);
accumulatore.lsw = argSq.lsw;
XSIG_LL(accumulatore) = XSIG_LL(argSq);
shr_Xsig(&argSq, 2*(-1-exponent-1));
shr_Xsig(&argSqSq, 4*(-1-exponent-1));
/* Now have argSq etc with binary point at the left
.1xxxxxxxx */
/* Do the basic fixed point polynomial evaluation */
accumulator.msw = accumulator.midw = accumulator.lsw = 0;
polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq),
oddplterms, HIPOWERop-1);
mul64_Xsig(&accumulator, &XSIG_LL(argSq));
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq), oddnegterms, HIPOWERon-1);
negate_Xsig(&accumulator);
add_two_Xsig(&accumulator, &fixedpterm, &dummy_exp);
mul64_Xsig(&accumulatore, &denomterm);
shr_Xsig(&accumulatore, 1 + 2*(-1-exponent));
accumulatore.msw |= 0x80000000;
div_Xsig(&accumulator, &accumulatore, &accumulator);
mul_Xsig_Xsig(&accumulator, &argSignif);
mul_Xsig_Xsig(&accumulator, &argSq);
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSignif);
if ( transformed )
{
/* compute pi/4 - accumulator */
shr_Xsig(&accumulator, -1-exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = -1;
}
if ( inverted )
{
/* compute pi/2 - accumulator */
shr_Xsig(&accumulator, -exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = 0;
}
if ( sign1 )
{
/* compute pi - accumulator */
shr_Xsig(&accumulator, 1 - exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = 1;
}
exponent += round_Xsig(&accumulator);
significand(st1_ptr) = XSIG_LL(accumulator);
setexponent16(st1_ptr, exponent);
tag = FPU_round(st1_ptr, 1, 0, FULL_PRECISION, sign2);
FPU_settagi(1, tag);
set_precision_flag_up(); /* We do not really know if up or down,
use this as the default. */
}
/*--- 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
/*--- poly_2xm1() -----------------------------------------------------------+
| Requires st(0) which is TAG_Valid and < 1. |
+---------------------------------------------------------------------------*/
int poly_2xm1(u_char sign, FPU_REG *arg, FPU_REG *result)
{
s32 exponent, shift;
u64 Xll;
Xsig accumulator, Denom, argSignif;
u_char tag;
exponent = exponent16(arg);
#ifdef PARANOID
if ( exponent >= 0 ) /* Don't want a |number| >= 1.0 */
{
/* 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 ( FPU_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 ( 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);
result = &st(0);
significand(result) = XSIG_LL(accumulator);
setexponent16(result, exponent);
tag = FPU_round(result, 1, 0, FULL_PRECISION, sign);
setsign(result, sign);
FPU_settag0(tag);
return 0;
}
void poly_atan(FPU_REG *st0_ptr, u_char st0_tag,
FPU_REG *st1_ptr, u_char st1_tag)
{
u_char transformed, inverted, sign1, sign2;
int exponent;
long int dummy_exp;
Xsig accumulator, Numer, Denom, accumulatore, argSignif, argSq, argSqSq;
u_char tag;
sign1 = getsign(st0_ptr);
sign2 = getsign(st1_ptr);
if (st0_tag == TAG_Valid) {
exponent = exponent(st0_ptr);
} else {
FPU_to_exp16(st0_ptr, st0_ptr);
exponent = exponent16(st0_ptr);
}
if (st1_tag == TAG_Valid) {
exponent -= exponent(st1_ptr);
} else {
FPU_to_exp16(st1_ptr, st1_ptr);
exponent -= exponent16(st1_ptr);
}
if ((exponent < 0) || ((exponent == 0) &&
((st0_ptr->sigh < st1_ptr->sigh) ||
((st0_ptr->sigh == st1_ptr->sigh) &&
(st0_ptr->sigl < st1_ptr->sigl))))) {
inverted = 1;
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = significand(st0_ptr);
XSIG_LL(Denom) = significand(st1_ptr);
} else {
inverted = 0;
exponent = -exponent;
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = significand(st1_ptr);
XSIG_LL(Denom) = significand(st0_ptr);
}
div_Xsig(&Numer, &Denom, &argSignif);
exponent += norm_Xsig(&argSignif);
if ((exponent >= -1)
|| ((exponent == -2) && (argSignif.msw > 0xd413ccd0))) {
transformed = 1;
if (exponent >= 0) {
#ifdef PARANOID
if (!((exponent == 0) &&
(argSignif.lsw == 0) && (argSignif.midw == 0) &&
(argSignif.msw == 0x80000000))) {
EXCEPTION(EX_INTERNAL | 0x104);
return;
}
#endif
argSignif.msw = 0;
} else {
Numer.lsw = Denom.lsw = argSignif.lsw;
XSIG_LL(Numer) = XSIG_LL(Denom) = XSIG_LL(argSignif);
if (exponent < -1)
shr_Xsig(&Numer, -1 - exponent);
negate_Xsig(&Numer);
shr_Xsig(&Denom, -exponent);
Denom.msw |= 0x80000000;
div_Xsig(&Numer, &Denom, &argSignif);
exponent = -1 + norm_Xsig(&argSignif);
}
} else {
transformed = 0;
}
argSq.lsw = argSignif.lsw;
argSq.midw = argSignif.midw;
argSq.msw = argSignif.msw;
mul_Xsig_Xsig(&argSq, &argSq);
argSqSq.lsw = argSq.lsw;
argSqSq.midw = argSq.midw;
argSqSq.msw = argSq.msw;
mul_Xsig_Xsig(&argSqSq, &argSqSq);
accumulatore.lsw = argSq.lsw;
XSIG_LL(accumulatore) = XSIG_LL(argSq);
shr_Xsig(&argSq, 2 * (-1 - exponent - 1));
shr_Xsig(&argSqSq, 4 * (-1 - exponent - 1));
accumulator.msw = accumulator.midw = accumulator.lsw = 0;
polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq),
oddplterms, HIPOWERop - 1);
mul64_Xsig(&accumulator, &XSIG_LL(argSq));
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq), oddnegterms,
HIPOWERon - 1);
negate_Xsig(&accumulator);
add_two_Xsig(&accumulator, &fixedpterm, &dummy_exp);
mul64_Xsig(&accumulatore, &denomterm);
shr_Xsig(&accumulatore, 1 + 2 * (-1 - exponent));
accumulatore.msw |= 0x80000000;
div_Xsig(&accumulator, &accumulatore, &accumulator);
mul_Xsig_Xsig(&accumulator, &argSignif);
mul_Xsig_Xsig(&accumulator, &argSq);
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSignif);
if (transformed) {
shr_Xsig(&accumulator, -1 - exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = -1;
}
if (inverted) {
shr_Xsig(&accumulator, -exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = 0;
}
if (sign1) {
shr_Xsig(&accumulator, 1 - exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = 1;
}
exponent += round_Xsig(&accumulator);
significand(st1_ptr) = XSIG_LL(accumulator);
setexponent16(st1_ptr, exponent);
tag = FPU_round(st1_ptr, 1, 0, FULL_PRECISION, sign2);
FPU_settagi(1, tag);
set_precision_flag_up();
}
int poly_2xm1(u_char sign, FPU_REG *arg, FPU_REG *result)
{
long int exponent, shift;
unsigned long long Xll;
Xsig accumulator, Denom, argSignif;
u_char tag;
exponent = exponent16(arg);
#ifdef PARANOID
if (exponent >= 0) { /* */
/* */
EXCEPTION(EX_INTERNAL | 0x127);
return 1;
}
#endif /* */
argSignif.lsw = 0;
XSIG_LL(argSignif) = Xll = significand(arg);
if (exponent == -1) {
shift = (argSignif.msw & 0x40000000) ? 3 : 2;
/* */
exponent -= 2;
XSIG_LL(argSignif) <<= 2;
Xll <<= 2;
} else if (exponent == -2) {
shift = 1;
/* */
exponent--;
XSIG_LL(argSignif) <<= 1;
Xll <<= 1;
} else
shift = 0;
if (exponent < -2) {
/* */
if (FPU_shrx(&Xll, -2 - exponent) >= 0x80000000U)
Xll++; /* */
}
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); /* */
add_two_Xsig(&accumulator, &argSignif, &exponent);
if (shift) {
/*
*/
shr_Xsig(&accumulator, -exponent);
accumulator.msw |= 0x80000000; /* */
mul_Xsig_Xsig(&accumulator, shiftterm[shift]);
accumulator.msw &= 0x3fffffff; /* */
exponent = 1;
}
if (sign != SIGN_POS) {
/*
*/
Denom.lsw = accumulator.lsw;
XSIG_LL(Denom) = XSIG_LL(accumulator);
if (exponent < 0)
shr_Xsig(&Denom, -exponent);
else if (exponent > 0) {
/* */
XSIG_LL(Denom) <<= 1;
if (Denom.lsw & 0x80000000)
XSIG_LL(Denom) |= 1;
(Denom.lsw) <<= 1;
}
Denom.msw |= 0x80000000; /* */
div_Xsig(&accumulator, &Denom, &accumulator);
}
/* */
exponent += round_Xsig(&accumulator);
result = &st(0);
significand(result) = XSIG_LL(accumulator);
setexponent16(result, exponent);
tag = FPU_round(result, 1, 0, FULL_PRECISION, sign);
setsign(result, sign);
FPU_settag0(tag);
return 0;
}
/*--- log2_kernel() ---------------------------------------------------------+
| Base 2 logarithm by a polynomial approximation. |
| log2(x+1) |
+---------------------------------------------------------------------------*/
static void log2_kernel(FPU_REG const *arg, u_char argsign, Xsig *accum_result,
long int *expon)
{
long int exponent, adj;
unsigned long long Xsq;
Xsig accumulator, Numer, Denom, argSignif, arg_signif;
exponent = exponent16(arg);
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = XSIG_LL(Denom) = significand(arg);
if (argsign == SIGN_POS) {
shr_Xsig(&Denom, 2 - (1 + exponent));
Denom.msw |= 0x80000000;
div_Xsig(&Numer, &Denom, &argSignif);
} else {
shr_Xsig(&Denom, 1 - (1 + exponent));
negate_Xsig(&Denom);
if (Denom.msw & 0x80000000) {
div_Xsig(&Numer, &Denom, &argSignif);
exponent++;
} else {
/* Denom must be 1.0 */
argSignif.lsw = Numer.lsw;
argSignif.midw = Numer.midw;
argSignif.msw = Numer.msw;
}
}
#ifndef PECULIAR_486
/* Should check here that |local_arg| is within the valid range */
if (exponent >= -2) {
if ((exponent > -2) || (argSignif.msw > (unsigned)0xafb0ccc0)) {
/* The argument is too large */
}
}
#endif /* PECULIAR_486 */
arg_signif.lsw = argSignif.lsw;
XSIG_LL(arg_signif) = XSIG_LL(argSignif);
adj = norm_Xsig(&argSignif);
accumulator.lsw = argSignif.lsw;
XSIG_LL(accumulator) = XSIG_LL(argSignif);
mul_Xsig_Xsig(&accumulator, &accumulator);
shr_Xsig(&accumulator, 2 * (-1 - (1 + exponent + adj)));
Xsq = XSIG_LL(accumulator);
if (accumulator.lsw & 0x80000000)
Xsq++;
accumulator.msw = accumulator.midw = accumulator.lsw = 0;
/* Do the basic fixed point polynomial evaluation */
polynomial_Xsig(&accumulator, &Xsq, logterms, HIPOWER - 1);
mul_Xsig_Xsig(&accumulator, &argSignif);
shr_Xsig(&accumulator, 6 - adj);
mul32_Xsig(&arg_signif, leadterm);
add_two_Xsig(&accumulator, &arg_signif, &exponent);
*expon = exponent + 1;
accum_result->lsw = accumulator.lsw;
accum_result->midw = accumulator.midw;
accum_result->msw = accumulator.msw;
}
/*--- poly_atan() -----------------------------------------------------------+
| |
+---------------------------------------------------------------------------*/
void poly_atan(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *result)
{
char transformed, inverted,
sign1 = arg1->sign, sign2 = arg2->sign;
long int exponent, dummy_exp;
Xsig accumulator, Numer, Denom, accumulatore, argSignif,
argSq, argSqSq;
arg1->sign = arg2->sign = SIGN_POS;
if ( (compare(arg2) & ~COMP_Denormal) == COMP_A_lt_B )
{
inverted = 1;
exponent = arg1->exp - arg2->exp;
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = significand(arg1);
XSIG_LL(Denom) = significand(arg2);
}
else
{
inverted = 0;
exponent = arg2->exp - arg1->exp;
Numer.lsw = Denom.lsw = 0;
XSIG_LL(Numer) = significand(arg2);
XSIG_LL(Denom) = significand(arg1);
}
div_Xsig(&Numer, &Denom, &argSignif);
exponent += norm_Xsig(&argSignif);
if ( (exponent >= -1)
|| ((exponent == -2) && (argSignif.msw > 0xd413ccd0)) )
{
/* The argument is greater than sqrt(2)-1 (=0.414213562...) */
/* Convert the argument by an identity for atan */
transformed = 1;
if ( exponent >= 0 )
{
#ifdef PARANOID
if ( !( (exponent == 0) &&
(argSignif.lsw == 0) && (argSignif.midw == 0) &&
(argSignif.msw == 0x80000000) ) )
{
EXCEPTION(EX_INTERNAL|0x104); /* There must be a logic error */
return;
}
#endif PARANOID
argSignif.msw = 0; /* Make the transformed arg -> 0.0 */
}
else
{
Numer.lsw = Denom.lsw = argSignif.lsw;
XSIG_LL(Numer) = XSIG_LL(Denom) = XSIG_LL(argSignif);
if ( exponent < -1 )
shr_Xsig(&Numer, -1-exponent);
negate_Xsig(&Numer);
shr_Xsig(&Denom, -exponent);
Denom.msw |= 0x80000000;
div_Xsig(&Numer, &Denom, &argSignif);
exponent = -1 + norm_Xsig(&argSignif);
}
}
else
{
transformed = 0;
}
argSq.lsw = argSignif.lsw; argSq.midw = argSignif.midw;
argSq.msw = argSignif.msw;
mul_Xsig_Xsig(&argSq, &argSq);
argSqSq.lsw = argSq.lsw; argSqSq.midw = argSq.midw; argSqSq.msw = argSq.msw;
mul_Xsig_Xsig(&argSqSq, &argSqSq);
accumulatore.lsw = argSq.lsw;
XSIG_LL(accumulatore) = XSIG_LL(argSq);
shr_Xsig(&argSq, 2*(-1-exponent-1));
shr_Xsig(&argSqSq, 4*(-1-exponent-1));
/* Now have argSq etc with binary point at the left
.1xxxxxxxx */
/* Do the basic fixed point polynomial evaluation */
accumulator.msw = accumulator.midw = accumulator.lsw = 0;
polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq),
oddplterms, HIPOWERop-1);
mul64_Xsig(&accumulator, &XSIG_LL(argSq));
negate_Xsig(&accumulator);
polynomial_Xsig(&accumulator, &XSIG_LL(argSqSq), oddnegterms, HIPOWERon-1);
negate_Xsig(&accumulator);
add_two_Xsig(&accumulator, &fixedpterm, &dummy_exp);
mul64_Xsig(&accumulatore, &denomterm);
shr_Xsig(&accumulatore, 1 + 2*(-1-exponent));
accumulatore.msw |= 0x80000000;
div_Xsig(&accumulator, &accumulatore, &accumulator);
mul_Xsig_Xsig(&accumulator, &argSignif);
mul_Xsig_Xsig(&accumulator, &argSq);
shr_Xsig(&accumulator, 3);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &argSignif);
if ( transformed )
{
/* compute pi/4 - accumulator */
shr_Xsig(&accumulator, -1-exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = -1;
}
if ( inverted )
{
/* compute pi/2 - accumulator */
shr_Xsig(&accumulator, -exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = 0;
}
if ( sign1 )
{
/* compute pi - accumulator */
shr_Xsig(&accumulator, 1 - exponent);
negate_Xsig(&accumulator);
add_Xsig_Xsig(&accumulator, &pi_signif);
exponent = 1;
}
exponent += round_Xsig(&accumulator);
significand(result) = XSIG_LL(accumulator);
result->exp = exponent + EXP_BIAS;
result->tag = TW_Valid;
result->sign = sign2;
}