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Make more progress on aarch64

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Justine Tunney 2023-05-03 00:00:09 -07:00
parent 135080fd3e
commit aef9a69a60
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42 changed files with 563 additions and 387 deletions
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libc/tinymath/sqrtf.c Normal file
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/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│ │
│ Musl Libc │
│ Copyright © 2005-2014 Rich Felker, et al. │
│ │
│ Permission is hereby granted, free of charge, to any person obtaining │
│ a copy of this software and associated documentation files (the │
│ "Software"), to deal in the Software without restriction, including │
│ without limitation the rights to use, copy, modify, merge, publish, │
│ distribute, sublicense, and/or sell copies of the Software, and to │
│ permit persons to whom the Software is furnished to do so, subject to │
│ the following conditions: │
│ │
│ The above copyright notice and this permission notice shall be │
│ included in all copies or substantial portions of the Software. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
│ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY │
│ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, │
│ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE │
│ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
│ │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/likely.h"
#include "libc/math.h"
#include "libc/tinymath/internal.h"
asm(".ident\t\"\\n\\n\
Musl libc (MIT License)\\n\
Copyright 2005-2014 Rich Felker, et. al.\"");
asm(".include \"libc/disclaimer.inc\"");
// clang-format off
#define FENV_SUPPORT 1
static inline uint32_t mul32(uint32_t a, uint32_t b)
{
return (uint64_t)a*b >> 32;
}
/* see sqrt.c for more detailed comments. */
float sqrtf(float x)
{
#ifdef __x86__
float res;
asm("sqrtss\t%1,%0" : "=x"(res) : "x"(x));
return res;
#else
uint32_t ix, m, m1, m0, even, ey;
ix = asuint(x);
if (UNLIKELY(ix - 0x00800000 >= 0x7f800000 - 0x00800000)) {
/* x < 0x1p-126 or inf or nan. */
if (ix * 2 == 0)
return x;
if (ix == 0x7f800000)
return x;
if (ix > 0x7f800000)
return __math_invalidf(x);
/* x is subnormal, normalize it. */
ix = asuint(x * 0x1p23f);
ix -= 23 << 23;
}
/* x = 4^e m; with int e and m in [1, 4). */
even = ix & 0x00800000;
m1 = (ix << 8) | 0x80000000;
m0 = (ix << 7) & 0x7fffffff;
m = even ? m0 : m1;
/* 2^e is the exponent part of the return value. */
ey = ix >> 1;
ey += 0x3f800000 >> 1;
ey &= 0x7f800000;
/* compute r ~ 1/sqrt(m), s ~ sqrt(m) with 2 goldschmidt iterations. */
static const uint32_t three = 0xc0000000;
uint32_t r, s, d, u, i;
i = (ix >> 17) % 128;
r = (uint32_t)__rsqrt_tab[i] << 16;
/* |r*sqrt(m) - 1| < 0x1p-8 */
s = mul32(m, r);
/* |s/sqrt(m) - 1| < 0x1p-8 */
d = mul32(s, r);
u = three - d;
r = mul32(r, u) << 1;
/* |r*sqrt(m) - 1| < 0x1.7bp-16 */
s = mul32(s, u) << 1;
/* |s/sqrt(m) - 1| < 0x1.7bp-16 */
d = mul32(s, r);
u = three - d;
s = mul32(s, u);
/* -0x1.03p-28 < s/sqrt(m) - 1 < 0x1.fp-31 */
s = (s - 1)>>6;
/* s < sqrt(m) < s + 0x1.08p-23 */
/* compute nearest rounded result. */
uint32_t d0, d1, d2;
float y, t;
d0 = (m << 16) - s*s;
d1 = s - d0;
d2 = d1 + s + 1;
s += d1 >> 31;
s &= 0x007fffff;
s |= ey;
y = asfloat(s);
if (FENV_SUPPORT) {
/* handle rounding and inexact exception. */
uint32_t tiny = UNLIKELY(d2==0) ? 0 : 0x01000000;
tiny |= (d1^d2) & 0x80000000;
t = asfloat(tiny);
y = eval_as_float(y + t);
}
return y;
#endif
}