diff options
Diffstat (limited to 'src/math/exp2f.c')
| -rw-r--r-- | src/math/exp2f.c | 30 |
1 files changed, 14 insertions, 16 deletions
diff --git a/src/math/exp2f.c b/src/math/exp2f.c index 55c22eac..279f32de 100644 --- a/src/math/exp2f.c +++ b/src/math/exp2f.c @@ -27,19 +27,15 @@ #include "libm.h" -#define TBLBITS 4 -#define TBLSIZE (1 << TBLBITS) +#define TBLSIZE 16 static const float -huge = 0x1p100f, redux = 0x1.8p23f / TBLSIZE, P1 = 0x1.62e430p-1f, P2 = 0x1.ebfbe0p-3f, P3 = 0x1.c6b348p-5f, P4 = 0x1.3b2c9cp-7f; -static const volatile float twom100 = 0x1p-100f; - static const double exp2ft[TBLSIZE] = { 0x1.6a09e667f3bcdp-1, 0x1.7a11473eb0187p-1, @@ -89,23 +85,25 @@ float exp2f(float x) { double tv, twopk, u, z; float t; - uint32_t hx, ix, i0; - int32_t k; + uint32_t hx, ix, i0, k; /* Filter out exceptional cases. */ GET_FLOAT_WORD(hx, x); ix = hx & 0x7fffffff; if (ix >= 0x43000000) { /* |x| >= 128 */ if (ix >= 0x7f800000) { - if ((ix & 0x7fffff) != 0 || (hx & 0x80000000) == 0) - return x + x; /* x is NaN or +Inf */ - else - return 0.0; /* x is -Inf */ + if (hx == 0xff800000) /* -inf */ + return 0; + return x; + } + if (x >= 128) { + STRICT_ASSIGN(float, x, x * 0x1p127); + return x; + } + if (x <= -150) { + STRICT_ASSIGN(float, x, 0x1p-100*0x1p-100); + return x; } - if (x >= 0x1.0p7f) - return huge * huge; /* overflow */ - if (x <= -0x1.2cp7f) - return twom100 * twom100; /* underflow */ } else if (ix <= 0x33000000) { /* |x| <= 0x1p-25 */ return 1.0f + x; } @@ -114,7 +112,7 @@ float exp2f(float x) STRICT_ASSIGN(float, t, x + redux); GET_FLOAT_WORD(i0, t); i0 += TBLSIZE / 2; - k = (i0 >> TBLBITS) << 20; + k = (i0 / TBLSIZE) << 20; i0 &= TBLSIZE - 1; t -= redux; z = x - t; |