57b08b0944
to reflect the new license. These used slightly different spellings that defeated my regular expressions. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351648
88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
/*===-- floatdisf.c - Implement __floatdisf -------------------------------===
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*
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* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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* See https://llvm.org/LICENSE.txt for license information.
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* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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*
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*===----------------------------------------------------------------------===
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*
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* This file implements __floatdisf for the compiler_rt library.
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*
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*===----------------------------------------------------------------------===
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*/
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/* Returns: convert a to a float, rounding toward even.*/
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/* Assumption: float is a IEEE 32 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 emmm mmmm mmmm mmmm mmmm mmmm */
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#include "int_lib.h"
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COMPILER_RT_ABI float
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__floatdisf(di_int a)
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{
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if (a == 0)
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return 0.0F;
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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 > FLT_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 FLT_MANT_DIG-1 bits to the right of 1
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* Q = bit FLT_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 FLT_MANT_DIG + 1:
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a <<= 1;
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break;
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case FLT_MANT_DIG + 2:
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break;
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default:
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a = ((du_int)a >> (sd - (FLT_MANT_DIG+2))) |
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((a & ((du_int)(-1) >> ((N + FLT_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 FLT_MANT_DIG or FLT_MANT_DIG+1 bits */
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if (a & ((du_int)1 << FLT_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 FLT_MANT_DIG bits */
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}
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else
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{
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a <<= (FLT_MANT_DIG - sd);
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/* a is now rounded to FLT_MANT_DIG bits */
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}
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float_bits fb;
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fb.u = ((su_int)s & 0x80000000) | /* sign */
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((e + 127) << 23) | /* exponent */
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((su_int)a & 0x007FFFFF); /* mantissa */
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return fb.f;
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}
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#if defined(__ARM_EABI__)
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#if defined(COMPILER_RT_ARMHF_TARGET)
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AEABI_RTABI float __aeabi_l2f(di_int a) {
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return __floatdisf(a);
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}
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#else
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AEABI_RTABI float __aeabi_l2f(di_int a) COMPILER_RT_ALIAS(__floatdisf);
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#endif
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#endif
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