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https://github.com/jart/cosmopolitan.git
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7e0a09feec
This change ports APE Loader to Linux AARCH64, so that Raspberry Pi users can run programs like redbean, without the executable needing to modify itself. Progress has also slipped into this change on the issue of making progress better conforming to user expectations and industry standards regarding which symbols we're allowed to declare
119 lines
3.7 KiB
C
119 lines
3.7 KiB
C
/* clang-format off */
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/*===-- floatdidf.c - Implement __floatdidf -------------------------------===
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*
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* The LLVM Compiler Infrastructure
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*
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* This file is dual licensed under the MIT and the University of Illinois Open
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* Source Licenses. See LICENSE.TXT for details.
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*
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*===----------------------------------------------------------------------===
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*
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* This file implements __floatdidf for the compiler_rt library.
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*
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*===----------------------------------------------------------------------===
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*/
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__static_yoink("huge_compiler_rt_license");
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#include "libc/literal.h"
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#include "third_party/compiler_rt/int_lib.h"
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/* Returns: convert a to a double, rounding toward even. */
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/* Assumption: double is a IEEE 64 bit floating point type
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* di_int is a 64 bit integral type
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*/
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/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
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#ifndef __SOFT_FP__
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/* Support for systems that have hardware floating-point; we'll set the inexact flag
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* as a side-effect of this computation.
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*/
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COMPILER_RT_ABI double
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__floatdidf(di_int a)
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{
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static const double twop52 = 4503599627370496.0; // 0x1.0p52
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static const double twop32 = 4294967296.0; // 0x1.0p32
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union { int64_t x; double d; } low = { .d = twop52 };
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const double high = (int32_t)(a >> 32) * twop32;
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low.x |= a & INT64_C(0x00000000ffffffff);
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const double result = (high - twop52) + low.d;
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return result;
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}
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#else
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/* Support for systems that don't have hardware floating-point; there are no flags to
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* set, and we don't want to code-gen to an unknown soft-float implementation.
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*/
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COMPILER_RT_ABI double
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__floatdidf(di_int a)
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{
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if (a == 0)
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return 0.0;
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const unsigned N = sizeof(di_int) * CHAR_BIT;
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const di_int s = a >> (N-1);
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a = (a ^ s) - s;
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int sd = N - __builtin_clzll(a); /* number of significant digits */
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int e = sd - 1; /* exponent */
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if (sd > DBL_MANT_DIG)
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{
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/* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
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* finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
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* 12345678901234567890123456
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* 1 = msb 1 bit
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* P = bit DBL_MANT_DIG-1 bits to the right of 1
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* Q = bit DBL_MANT_DIG bits to the right of 1
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* R = "or" of all bits to the right of Q
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*/
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switch (sd)
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{
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case DBL_MANT_DIG + 1:
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a <<= 1;
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break;
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case DBL_MANT_DIG + 2:
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break;
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default:
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a = ((du_int)a >> (sd - (DBL_MANT_DIG+2))) |
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((a & ((du_int)(-1) >> ((N + DBL_MANT_DIG+2) - sd))) != 0);
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};
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/* finish: */
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a |= (a & 4) != 0; /* Or P into R */
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++a; /* round - this step may add a significant bit */
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a >>= 2; /* dump Q and R */
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/* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */
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if (a & ((du_int)1 << DBL_MANT_DIG))
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{
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a >>= 1;
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++e;
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}
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/* a is now rounded to DBL_MANT_DIG bits */
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}
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else
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{
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a <<= (DBL_MANT_DIG - sd);
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/* a is now rounded to DBL_MANT_DIG bits */
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}
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double_bits fb;
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fb.u.s.high = ((su_int)s & 0x80000000) | /* sign */
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((e + 1023) << 20) | /* exponent */
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((su_int)(a >> 32) & 0x000FFFFF); /* mantissa-high */
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fb.u.s.low = (su_int)a; /* mantissa-low */
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return fb.f;
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}
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#endif
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#if defined(__ARM_EABI__)
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#if defined(COMPILER_RT_ARMHF_TARGET)
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AEABI_RTABI double __aeabi_l2d(di_int a) {
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return __floatdidf(a);
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}
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#else
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AEABI_RTABI double __aeabi_l2d(di_int a) COMPILER_RT_ALIAS(__floatdidf);
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#endif
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#endif
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