117 lines
1.9 KiB
C
117 lines
1.9 KiB
C
/* Copyright 2017 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "common.h"
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#ifdef CONFIG_FPU
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union ieee_float_shape_type {
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float value;
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uint32_t word;
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};
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/* Get a 32 bit int from a float. */
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#define GET_FLOAT_WORD(i, d) \
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do { \
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union ieee_float_shape_type gf_u; \
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gf_u.value = (d); \
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(i) = gf_u.word; \
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} while (0)
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/* Set a float from a 32 bit int. */
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#define SET_FLOAT_WORD(d, i) \
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do { \
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union ieee_float_shape_type sf_u; \
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sf_u.word = (i); \
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(d) = sf_u.value; \
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} while (0)
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float fabsf(float x)
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{
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uint32_t ix;
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GET_FLOAT_WORD(ix, x);
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SET_FLOAT_WORD(x, (ix & 0x7fffffff));
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return x;
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}
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#define FLT_UWORD_IS_ZERO(x) ((x) == 0)
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#define FLT_UWORD_IS_SUBNORMAL(x) ((x) < 0x00800000L)
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#define FLT_UWORD_IS_FINITE(x) ((x) < 0x7f800000L)
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static const float one = 1.0f, tiny = 1.0e-30f;
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static float __ieee754_sqrtf(float x)
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{
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float z;
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uint32_t r, hx;
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int32_t ix, s, q, m, t, i;
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GET_FLOAT_WORD(ix, x);
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hx = ix & 0x7fffffff;
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/*
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* take care of Inf and NaN
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* sqrt(NaN)=NaN, sqrt(+inf)=+inf, sqrt(-inf)=sNaN
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*/
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if (!FLT_UWORD_IS_FINITE(hx))
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return x * x + x;
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/* take care of zero and -ves */
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if (FLT_UWORD_IS_ZERO(hx))
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return x;
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if (ix < 0)
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return (x - x) / (x - x);
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m = (ix >> 23);
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if (FLT_UWORD_IS_SUBNORMAL(hx)) {
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for (i = 0; (ix & 0x00800000L) == 0; i++)
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ix <<= 1;
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m -= i - 1;
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}
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m -= 127;
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ix = (ix & 0x007fffffL) | 0x00800000L;
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if (m & 1)
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ix += ix;
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m >>= 1;
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ix += ix;
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q = s = 0;
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r = 0x01000000L;
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while (r != 0) {
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t = s + r;
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if (t <= ix) {
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s = t + r;
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ix -= t;
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q += r;
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}
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ix += ix;
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r >>= 1;
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}
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if (ix != 0) {
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z = one - tiny;
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if (z >= one) {
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z = one + tiny;
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if (z > one)
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q += 2;
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else
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q += (q & 1);
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}
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}
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ix = (q >> 1) + 0x3f000000L;
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ix += (m << 23);
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SET_FLOAT_WORD(z, ix);
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return z;
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}
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float sqrtf(float x)
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{
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return __ieee754_sqrtf(x);
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}
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#endif
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