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5130b81eec
circuitpython/cortex-m3-qemu/math.c
Ilya Dmitrichenko 5130b81eec cortex-m3-qemu: a working port
2014-04-21 21:04:04 +01:00

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#include <stdint.h>
#include <math.h>
typedef float float_t;
typedef union {
float f;
struct {
uint64_t m : 23;
uint64_t e : 8;
uint64_t s : 1;
};
} float_s_t;
typedef union {
double d;
struct {
uint64_t m : 52;
uint64_t e : 11;
uint64_t s : 1;
};
} double_s_t;
float sqrtf(float x) {
return x;
}
// some compilers define log2f in terms of logf
#ifdef log2f
#undef log2f
#endif
float log2f(float x) { return 0; }
static const float _M_LN10 = 2.30258509299404; // 0x40135d8e
float log10f(float x) { return logf(x) / (float)_M_LN10; }
float tanhf(float x) { return sinhf(x) / coshf(x); }
// TODO we need import these functions from some library (eg musl or newlib)
float acoshf(float x) { return 0.0; }
float asinhf(float x) { return 0.0; }
float atanhf(float x) { return 0.0; }
float cosf(float x) { return 0.0; }
float sinf(float x) { return 0.0; }
float tanf(float x) { return 0.0; }
float acosf(float x) { return 0.0; }
float asinf(float x) { return 0.0; }
float atanf(float x) { return 0.0; }
float atan2f(float x, float y) { return 0.0; }
float ceilf(float x) { return 0.0; }
float floorf(float x) { return 0.0; }
float truncf(float x) { return 0.0; }
float fmodf(float x, float y) { return 0.0; }
float tgammaf(float x) { return 0.0; }
float lgammaf(float x) { return 0.0; }
float erff(float x) { return 0.0; }
float erfcf(float x) { return 0.0; }
float modff(float x, float *y) { return 0.0; }
float frexpf(float x, int *exp) { return 0.0; }
float ldexpf(float x, int exp) { return 0.0; }
/*****************************************************************************/
/*****************************************************************************/
// from musl-0.9.15 libm.h
/*****************************************************************************/
/*****************************************************************************/
/* origin: FreeBSD /usr/src/lib/msun/src/math_private.h */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#define FORCE_EVAL(x) do { \
if (sizeof(x) == sizeof(float)) { \
volatile float __x; \
__x = (x); \
(void)__x; \
} else if (sizeof(x) == sizeof(double)) { \
volatile double __x; \
__x = (x); \
(void)__x; \
} else { \
volatile long double __x; \
__x = (x); \
(void)__x; \
} \
} while(0)
/* Get a 32 bit int from a float. */
#define GET_FLOAT_WORD(w,d) \
do { \
union {float f; uint32_t i;} __u; \
__u.f = (d); \
(w) = __u.i; \
} while (0)
/* Set a float from a 32 bit int. */
#define SET_FLOAT_WORD(d,w) \
do { \
union {float f; uint32_t i;} __u; \
__u.i = (w); \
(d) = __u.f; \
} while (0)
/*****************************************************************************/
/*****************************************************************************/
// __fpclassifyf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
int __fpclassifyf(float x)
{
union {float f; uint32_t i;} u = {x};
int e = u.i>>23 & 0xff;
if (!e) return u.i<<1 ? FP_SUBNORMAL : FP_ZERO;
if (e==0xff) return u.i<<9 ? FP_NAN : FP_INFINITE;
return FP_NORMAL;
}
/*****************************************************************************/
/*****************************************************************************/
// scalbnf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
float scalbnf(float x, int n)
{
union {float f; uint32_t i;} u;
float_t y = x;
if (n > 127) {
y *= 0x1p127f;
n -= 127;
if (n > 127) {
y *= 0x1p127f;
n -= 127;
if (n > 127)
n = 127;
}
} else if (n < -126) {
y *= 0x1p-126f;
n += 126;
if (n < -126) {
y *= 0x1p-126f;
n += 126;
if (n < -126)
n = -126;
}
}
u.i = (uint32_t)(0x7f+n)<<23;
x = y * u.f;
return x;
}
/*****************************************************************************/
/*****************************************************************************/
// powf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
/* origin: FreeBSD /usr/src/lib/msun/src/e_powf.c */
/*
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
static const float
bp[] = {1.0, 1.5,},
dp_h[] = { 0.0, 5.84960938e-01,}, /* 0x3f15c000 */
dp_l[] = { 0.0, 1.56322085e-06,}, /* 0x35d1cfdc */
two24 = 16777216.0, /* 0x4b800000 */
huge = 1.0e30,
tiny = 1.0e-30,
/* poly coefs for (3/2)*(log(x)-2s-2/3*s**3 */
L1 = 6.0000002384e-01, /* 0x3f19999a */
L2 = 4.2857143283e-01, /* 0x3edb6db7 */
L3 = 3.3333334327e-01, /* 0x3eaaaaab */
L4 = 2.7272811532e-01, /* 0x3e8ba305 */
L5 = 2.3066075146e-01, /* 0x3e6c3255 */
L6 = 2.0697501302e-01, /* 0x3e53f142 */
P1 = 1.6666667163e-01, /* 0x3e2aaaab */
P2 = -2.7777778450e-03, /* 0xbb360b61 */
P3 = 6.6137559770e-05, /* 0x388ab355 */
P4 = -1.6533901999e-06, /* 0xb5ddea0e */
P5 = 4.1381369442e-08, /* 0x3331bb4c */
lg2 = 6.9314718246e-01, /* 0x3f317218 */
lg2_h = 6.93145752e-01, /* 0x3f317200 */
lg2_l = 1.42860654e-06, /* 0x35bfbe8c */
ovt = 4.2995665694e-08, /* -(128-log2(ovfl+.5ulp)) */
cp = 9.6179670095e-01, /* 0x3f76384f =2/(3ln2) */
cp_h = 9.6191406250e-01, /* 0x3f764000 =12b cp */
cp_l = -1.1736857402e-04, /* 0xb8f623c6 =tail of cp_h */
ivln2 = 1.4426950216e+00, /* 0x3fb8aa3b =1/ln2 */
ivln2_h = 1.4426879883e+00, /* 0x3fb8aa00 =16b 1/ln2*/
ivln2_l = 7.0526075433e-06; /* 0x36eca570 =1/ln2 tail*/
float powf(float x, float y)
{
float z,ax,z_h,z_l,p_h,p_l;
float y1,t1,t2,r,s,sn,t,u,v,w;
int32_t i,j,k,yisint,n;
int32_t hx,hy,ix,iy,is;
GET_FLOAT_WORD(hx, x);
GET_FLOAT_WORD(hy, y);
ix = hx & 0x7fffffff;
iy = hy & 0x7fffffff;
/* x**0 = 1, even if x is NaN */
if (iy == 0)
return 1.0f;
/* 1**y = 1, even if y is NaN */
if (hx == 0x3f800000)
return 1.0f;
/* NaN if either arg is NaN */
if (ix > 0x7f800000 || iy > 0x7f800000)
return x + y;
/* determine if y is an odd int when x < 0
* yisint = 0 ... y is not an integer
* yisint = 1 ... y is an odd int
* yisint = 2 ... y is an even int
*/
yisint = 0;
if (hx < 0) {
if (iy >= 0x4b800000)
yisint = 2; /* even integer y */
else if (iy >= 0x3f800000) {
k = (iy>>23) - 0x7f; /* exponent */
j = iy>>(23-k);
if ((j<<(23-k)) == iy)
yisint = 2 - (j & 1);
}
}
/* special value of y */
if (iy == 0x7f800000) { /* y is +-inf */
if (ix == 0x3f800000) /* (-1)**+-inf is 1 */
return 1.0f;
else if (ix > 0x3f800000) /* (|x|>1)**+-inf = inf,0 */
return hy >= 0 ? y : 0.0f;
else if (ix != 0) /* (|x|<1)**+-inf = 0,inf if x!=0 */
return hy >= 0 ? 0.0f: -y;
}
if (iy == 0x3f800000) /* y is +-1 */
return hy >= 0 ? x : 1.0f/x;
if (hy == 0x40000000) /* y is 2 */
return x*x;
if (hy == 0x3f000000) { /* y is 0.5 */
if (hx >= 0) /* x >= +0 */
return sqrtf(x);
}
ax = fabsf(x);
/* special value of x */
if (ix == 0x7f800000 || ix == 0 || ix == 0x3f800000) { /* x is +-0,+-inf,+-1 */
z = ax;
if (hy < 0) /* z = (1/|x|) */
z = 1.0f/z;
if (hx < 0) {
if (((ix-0x3f800000)|yisint) == 0) {
z = (z-z)/(z-z); /* (-1)**non-int is NaN */
} else if (yisint == 1)
z = -z; /* (x<0)**odd = -(|x|**odd) */
}
return z;
}
sn = 1.0f; /* sign of result */
if (hx < 0) {
if (yisint == 0) /* (x<0)**(non-int) is NaN */
return (x-x)/(x-x);
if (yisint == 1) /* (x<0)**(odd int) */
sn = -1.0f;
}
/* |y| is huge */
if (iy > 0x4d000000) { /* if |y| > 2**27 */
/* over/underflow if x is not close to one */
if (ix < 0x3f7ffff8)
return hy < 0 ? sn*huge*huge : sn*tiny*tiny;
if (ix > 0x3f800007)
return hy > 0 ? sn*huge*huge : sn*tiny*tiny;
/* now |1-x| is tiny <= 2**-20, suffice to compute
log(x) by x-x^2/2+x^3/3-x^4/4 */
t = ax - 1; /* t has 20 trailing zeros */
w = (t*t)*(0.5f - t*(0.333333333333f - t*0.25f));
u = ivln2_h*t; /* ivln2_h has 16 sig. bits */
v = t*ivln2_l - w*ivln2;
t1 = u + v;
GET_FLOAT_WORD(is, t1);
SET_FLOAT_WORD(t1, is & 0xfffff000);
t2 = v - (t1-u);
} else {
float s2,s_h,s_l,t_h,t_l;
n = 0;
/* take care subnormal number */
if (ix < 0x00800000) {
ax *= two24;
n -= 24;
GET_FLOAT_WORD(ix, ax);
}
n += ((ix)>>23) - 0x7f;
j = ix & 0x007fffff;
/* determine interval */
ix = j | 0x3f800000; /* normalize ix */
if (j <= 0x1cc471) /* |x|<sqrt(3/2) */
k = 0;
else if (j < 0x5db3d7) /* |x|<sqrt(3) */
k = 1;
else {
k = 0;
n += 1;
ix -= 0x00800000;
}
SET_FLOAT_WORD(ax, ix);
/* compute s = s_h+s_l = (x-1)/(x+1) or (x-1.5)/(x+1.5) */
u = ax - bp[k]; /* bp[0]=1.0, bp[1]=1.5 */
v = 1.0f/(ax+bp[k]);
s = u*v;
s_h = s;
GET_FLOAT_WORD(is, s_h);
SET_FLOAT_WORD(s_h, is & 0xfffff000);
/* t_h=ax+bp[k] High */
is = ((ix>>1) & 0xfffff000) | 0x20000000;
SET_FLOAT_WORD(t_h, is + 0x00400000 + (k<<21));
t_l = ax - (t_h - bp[k]);
s_l = v*((u - s_h*t_h) - s_h*t_l);
/* compute log(ax) */
s2 = s*s;
r = s2*s2*(L1+s2*(L2+s2*(L3+s2*(L4+s2*(L5+s2*L6)))));
r += s_l*(s_h+s);
s2 = s_h*s_h;
t_h = 3.0f + s2 + r;
GET_FLOAT_WORD(is, t_h);
SET_FLOAT_WORD(t_h, is & 0xfffff000);
t_l = r - ((t_h - 3.0f) - s2);
/* u+v = s*(1+...) */
u = s_h*t_h;
v = s_l*t_h + t_l*s;
/* 2/(3log2)*(s+...) */
p_h = u + v;
GET_FLOAT_WORD(is, p_h);
SET_FLOAT_WORD(p_h, is & 0xfffff000);
p_l = v - (p_h - u);
z_h = cp_h*p_h; /* cp_h+cp_l = 2/(3*log2) */
z_l = cp_l*p_h + p_l*cp+dp_l[k];
/* log2(ax) = (s+..)*2/(3*log2) = n + dp_h + z_h + z_l */
t = (float)n;
t1 = (((z_h + z_l) + dp_h[k]) + t);
GET_FLOAT_WORD(is, t1);
SET_FLOAT_WORD(t1, is & 0xfffff000);
t2 = z_l - (((t1 - t) - dp_h[k]) - z_h);
}
/* split up y into y1+y2 and compute (y1+y2)*(t1+t2) */
GET_FLOAT_WORD(is, y);
SET_FLOAT_WORD(y1, is & 0xfffff000);
p_l = (y-y1)*t1 + y*t2;
p_h = y1*t1;
z = p_l + p_h;
GET_FLOAT_WORD(j, z);
if (j > 0x43000000) /* if z > 128 */
return sn*huge*huge; /* overflow */
else if (j == 0x43000000) { /* if z == 128 */
if (p_l + ovt > z - p_h)
return sn*huge*huge; /* overflow */
} else if ((j&0x7fffffff) > 0x43160000) /* z < -150 */ // FIXME: check should be (uint32_t)j > 0xc3160000
return sn*tiny*tiny; /* underflow */
else if (j == 0xc3160000) { /* z == -150 */
if (p_l <= z-p_h)
return sn*tiny*tiny; /* underflow */
}
/*
* compute 2**(p_h+p_l)
*/
i = j & 0x7fffffff;
k = (i>>23) - 0x7f;
n = 0;
if (i > 0x3f000000) { /* if |z| > 0.5, set n = [z+0.5] */
n = j + (0x00800000>>(k+1));
k = ((n&0x7fffffff)>>23) - 0x7f; /* new k for n */
SET_FLOAT_WORD(t, n & ~(0x007fffff>>k));
n = ((n&0x007fffff)|0x00800000)>>(23-k);
if (j < 0)
n = -n;
p_h -= t;
}
t = p_l + p_h;
GET_FLOAT_WORD(is, t);
SET_FLOAT_WORD(t, is & 0xffff8000);
u = t*lg2_h;
v = (p_l-(t-p_h))*lg2 + t*lg2_l;
z = u + v;
w = v - (z - u);
t = z*z;
t1 = z - t*(P1+t*(P2+t*(P3+t*(P4+t*P5))));
r = (z*t1)/(t1-2.0f) - (w+z*w);
z = 1.0f - (r - z);
GET_FLOAT_WORD(j, z);
j += n<<23;
if ((j>>23) <= 0) /* subnormal output */
z = scalbnf(z, n);
else
SET_FLOAT_WORD(z, j);
return sn*z;
}
/*****************************************************************************/
/*****************************************************************************/
// expf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
/* origin: FreeBSD /usr/src/lib/msun/src/e_expf.c */
/*
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
static const float
half[2] = {0.5,-0.5},
ln2hi = 6.9314575195e-1f, /* 0x3f317200 */
ln2lo = 1.4286067653e-6f, /* 0x35bfbe8e */
invln2 = 1.4426950216e+0f, /* 0x3fb8aa3b */
/*
* Domain [-0.34568, 0.34568], range ~[-4.278e-9, 4.447e-9]:
* |x*(exp(x)+1)/(exp(x)-1) - p(x)| < 2**-27.74
*/
expf_P1 = 1.6666625440e-1f, /* 0xaaaa8f.0p-26 */
expf_P2 = -2.7667332906e-3f; /* -0xb55215.0p-32 */
float expf(float x)
{
float_t hi, lo, c, xx, y;
int k, sign;
uint32_t hx;
GET_FLOAT_WORD(hx, x);
sign = hx >> 31; /* sign bit of x */
hx &= 0x7fffffff; /* high word of |x| */
/* special cases */
if (hx >= 0x42aeac50) { /* if |x| >= -87.33655f or NaN */
if (hx >= 0x42b17218 && !sign) { /* x >= 88.722839f */
/* overflow */
x *= 0x1p127f;
return x;
}
if (sign) {
/* underflow */
FORCE_EVAL(-0x1p-149f/x);
if (hx >= 0x42cff1b5) /* x <= -103.972084f */
return 0;
}
}
/* argument reduction */
if (hx > 0x3eb17218) { /* if |x| > 0.5 ln2 */
if (hx > 0x3f851592) /* if |x| > 1.5 ln2 */
k = invln2*x + half[sign];
else
k = 1 - sign - sign;
hi = x - k*ln2hi; /* k*ln2hi is exact here */
lo = k*ln2lo;
x = hi - lo;
} else if (hx > 0x39000000) { /* |x| > 2**-14 */
k = 0;
hi = x;
lo = 0;
} else {
/* raise inexact */
FORCE_EVAL(0x1p127f + x);
return 1 + x;
}
/* x is now in primary range */
xx = x*x;
c = x - xx*(expf_P1+xx*expf_P2);
y = 1 + (x*c/(2-c) - lo + hi);
if (k == 0)
return y;
return scalbnf(y, k);
}
/*****************************************************************************/
/*****************************************************************************/
// expm1f from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
/* origin: FreeBSD /usr/src/lib/msun/src/s_expm1f.c */
/*
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
static const float
o_threshold = 8.8721679688e+01, /* 0x42b17180 */
ln2_hi = 6.9313812256e-01, /* 0x3f317180 */
ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */
//invln2 = 1.4426950216e+00, /* 0x3fb8aa3b */
/*
* Domain [-0.34568, 0.34568], range ~[-6.694e-10, 6.696e-10]:
* |6 / x * (1 + 2 * (1 / (exp(x) - 1) - 1 / x)) - q(x)| < 2**-30.04
* Scaled coefficients: Qn_here = 2**n * Qn_for_q (see s_expm1.c):
*/
Q1 = -3.3333212137e-2, /* -0x888868.0p-28 */
Q2 = 1.5807170421e-3; /* 0xcf3010.0p-33 */
float expm1f(float x)
{
float_t y,hi,lo,c,t,e,hxs,hfx,r1,twopk;
union {float f; uint32_t i;} u = {x};
uint32_t hx = u.i & 0x7fffffff;
int k, sign = u.i >> 31;
/* filter out huge and non-finite argument */
if (hx >= 0x4195b844) { /* if |x|>=27*ln2 */
if (hx > 0x7f800000) /* NaN */
return x;
if (sign)
return -1;
if (x > o_threshold) {
x *= 0x1p127f;
return x;
}
}
/* argument reduction */
if (hx > 0x3eb17218) { /* if |x| > 0.5 ln2 */
if (hx < 0x3F851592) { /* and |x| < 1.5 ln2 */
if (!sign) {
hi = x - ln2_hi;
lo = ln2_lo;
k = 1;
} else {
hi = x + ln2_hi;
lo = -ln2_lo;
k = -1;
}
} else {
k = invln2*x + (sign ? -0.5f : 0.5f);
t = k;
hi = x - t*ln2_hi; /* t*ln2_hi is exact here */
lo = t*ln2_lo;
}
x = hi-lo;
c = (hi-x)-lo;
} else if (hx < 0x33000000) { /* when |x|<2**-25, return x */
if (hx < 0x00800000)
FORCE_EVAL(x*x);
return x;
} else
k = 0;
/* x is now in primary range */
hfx = 0.5f*x;
hxs = x*hfx;
r1 = 1.0f+hxs*(Q1+hxs*Q2);
t = 3.0f - r1*hfx;
e = hxs*((r1-t)/(6.0f - x*t));
if (k == 0) /* c is 0 */
return x - (x*e-hxs);
e = x*(e-c) - c;
e -= hxs;
/* exp(x) ~ 2^k (x_reduced - e + 1) */
if (k == -1)
return 0.5f*(x-e) - 0.5f;
if (k == 1) {
if (x < -0.25f)
return -2.0f*(e-(x+0.5f));
return 1.0f + 2.0f*(x-e);
}
u.i = (0x7f+k)<<23; /* 2^k */
twopk = u.f;
if (k < 0 || k > 56) { /* suffice to return exp(x)-1 */
y = x - e + 1.0f;
if (k == 128)
y = y*2.0f*0x1p127f;
else
y = y*twopk;
return y - 1.0f;
}
u.i = (0x7f-k)<<23; /* 2^-k */
if (k < 23)
y = (x-e+(1-u.f))*twopk;
else
y = (x-(e+u.f)+1)*twopk;
return y;
}
/*****************************************************************************/
/*****************************************************************************/
// __expo2f from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
/* k is such that k*ln2 has minimal relative error and x - kln2 > log(FLT_MIN) */
static const int k = 235;
static const float kln2 = 0x1.45c778p+7f;
/* expf(x)/2 for x >= log(FLT_MAX), slightly better than 0.5f*expf(x/2)*expf(x/2) */
float __expo2f(float x)
{
float scale;
/* note that k is odd and scale*scale overflows */
SET_FLOAT_WORD(scale, (uint32_t)(0x7f + k/2) << 23);
/* exp(x - k ln2) * 2**(k-1) */
return expf(x - kln2) * scale * scale;
}
/*****************************************************************************/
/*****************************************************************************/
// logf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
/* origin: FreeBSD /usr/src/lib/msun/src/e_logf.c */
/*
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
static const float
/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */
Lg2 = 0xccce13.0p-25, /* 0.40000972152 */
Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */
Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */
float logf(float x)
{
union {float f; uint32_t i;} u = {x};
float_t hfsq,f,s,z,R,w,t1,t2,dk;
uint32_t ix;
int k;
ix = u.i;
k = 0;
if (ix < 0x00800000 || ix>>31) { /* x < 2**-126 */
if (ix<<1 == 0)
return -1/(x*x); /* log(+-0)=-inf */
if (ix>>31)
return (x-x)/0.0f; /* log(-#) = NaN */
/* subnormal number, scale up x */
k -= 25;
x *= 0x1p25f;
u.f = x;
ix = u.i;
} else if (ix >= 0x7f800000) {
return x;
} else if (ix == 0x3f800000)
return 0;
/* reduce x into [sqrt(2)/2, sqrt(2)] */
ix += 0x3f800000 - 0x3f3504f3;
k += (int)(ix>>23) - 0x7f;
ix = (ix&0x007fffff) + 0x3f3504f3;
u.i = ix;
x = u.f;
f = x - 1.0f;
s = f/(2.0f + f);
z = s*s;
w = z*z;
t1= w*(Lg2+w*Lg4);
t2= z*(Lg1+w*Lg3);
R = t2 + t1;
hfsq = 0.5f*f*f;
dk = k;
return s*(hfsq+R) + dk*ln2_lo - hfsq + f + dk*ln2_hi;
}
/*****************************************************************************/
/*****************************************************************************/
// coshf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
float coshf(float x)
{
union {float f; uint32_t i;} u = {.f = x};
uint32_t w;
float t;
/* |x| */
u.i &= 0x7fffffff;
x = u.f;
w = u.i;
/* |x| < log(2) */
if (w < 0x3f317217) {
if (w < 0x3f800000 - (12<<23)) {
FORCE_EVAL(x + 0x1p120f);
return 1;
}
t = expm1f(x);
return 1 + t*t/(2*(1+t));
}
/* |x| < log(FLT_MAX) */
if (w < 0x42b17217) {
t = expf(x);
return 0.5f*(t + 1/t);
}
/* |x| > log(FLT_MAX) or nan */
t = __expo2f(x);
return t;
}
/*****************************************************************************/
/*****************************************************************************/
// sinhf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
float sinhf(float x)
{
union {float f; uint32_t i;} u = {.f = x};
uint32_t w;
float t, h, absx;
h = 0.5;
if (u.i >> 31)
h = -h;
/* |x| */
u.i &= 0x7fffffff;
absx = u.f;
w = u.i;
/* |x| < log(FLT_MAX) */
if (w < 0x42b17217) {
t = expm1f(absx);
if (w < 0x3f800000) {
if (w < 0x3f800000 - (12<<23))
return x;
return h*(2*t - t*t/(t+1));
}
return h*(t + t/(t+1));
}
/* |x| > logf(FLT_MAX) or nan */
t = 2*h*__expo2f(absx);
return t;
}
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