mirror of
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
86 lines
2.8 KiB
C
86 lines
2.8 KiB
C
/* clang-format off */
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/* ===-- floattidf.c - Implement __floattidf -------------------------------===
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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 __floattidf 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 "third_party/compiler_rt/int_lib.h"
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#ifdef CRT_HAS_128BIT
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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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* ti_int is a 128 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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COMPILER_RT_ABI double
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__floattidf(ti_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(ti_int) * CHAR_BIT;
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const ti_int s = a >> (N-1);
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a = (a ^ s) - s;
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int sd = N - __clzti2(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 = ((tu_int)a >> (sd - (DBL_MANT_DIG+2))) |
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((a & ((tu_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 & ((tu_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 /* CRT_HAS_128BIT */
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