diff options
Diffstat (limited to 'lib/builtins/floatdidf.c')
| -rw-r--r-- | lib/builtins/floatdidf.c | 170 |
1 files changed, 79 insertions, 91 deletions
diff --git a/lib/builtins/floatdidf.c b/lib/builtins/floatdidf.c index 36b856e07..8f887314b 100644 --- a/lib/builtins/floatdidf.c +++ b/lib/builtins/floatdidf.c @@ -1,115 +1,103 @@ -/*===-- floatdidf.c - Implement __floatdidf -------------------------------=== - * - * The LLVM Compiler Infrastructure - * - * This file is dual licensed under the MIT and the University of Illinois Open - * Source Licenses. See LICENSE.TXT for details. - * - *===----------------------------------------------------------------------=== - * - * This file implements __floatdidf for the compiler_rt library. - * - *===----------------------------------------------------------------------=== - */ +//===-- floatdidf.c - Implement __floatdidf -------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements __floatdidf for the compiler_rt library. +// +//===----------------------------------------------------------------------===// #include "int_lib.h" -/* Returns: convert a to a double, rounding toward even. */ +// Returns: convert a to a double, rounding toward even. -/* Assumption: double is a IEEE 64 bit floating point type - * di_int is a 64 bit integral type - */ +// Assumption: double is a IEEE 64 bit floating point type +// di_int is a 64 bit integral type -/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */ +// seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm +// mmmm #ifndef __SOFT_FP__ -/* Support for systems that have hardware floating-point; we'll set the inexact flag - * as a side-effect of this computation. - */ +// Support for systems that have hardware floating-point; we'll set the inexact +// flag as a side-effect of this computation. -COMPILER_RT_ABI double -__floatdidf(di_int a) -{ - static const double twop52 = 4503599627370496.0; // 0x1.0p52 - static const double twop32 = 4294967296.0; // 0x1.0p32 +COMPILER_RT_ABI double __floatdidf(di_int a) { + static const double twop52 = 4503599627370496.0; // 0x1.0p52 + static const double twop32 = 4294967296.0; // 0x1.0p32 - union { int64_t x; double d; } low = { .d = twop52 }; + union { + int64_t x; + double d; + } low = {.d = twop52}; - const double high = (int32_t)(a >> 32) * twop32; - low.x |= a & INT64_C(0x00000000ffffffff); + const double high = (int32_t)(a >> 32) * twop32; + low.x |= a & INT64_C(0x00000000ffffffff); - const double result = (high - twop52) + low.d; - return result; + const double result = (high - twop52) + low.d; + return result; } #else -/* Support for systems that don't have hardware floating-point; there are no flags to - * set, and we don't want to code-gen to an unknown soft-float implementation. - */ +// Support for systems that don't have hardware floating-point; there are no +// flags to set, and we don't want to code-gen to an unknown soft-float +// implementation. -COMPILER_RT_ABI double -__floatdidf(di_int a) -{ - if (a == 0) - return 0.0; - const unsigned N = sizeof(di_int) * CHAR_BIT; - const di_int s = a >> (N-1); - a = (a ^ s) - s; - int sd = N - __builtin_clzll(a); /* number of significant digits */ - int e = sd - 1; /* exponent */ - if (sd > DBL_MANT_DIG) - { - /* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx - * finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR - * 12345678901234567890123456 - * 1 = msb 1 bit - * P = bit DBL_MANT_DIG-1 bits to the right of 1 - * Q = bit DBL_MANT_DIG bits to the right of 1 - * R = "or" of all bits to the right of Q - */ - switch (sd) - { - case DBL_MANT_DIG + 1: - a <<= 1; - break; - case DBL_MANT_DIG + 2: - break; - default: - a = ((du_int)a >> (sd - (DBL_MANT_DIG+2))) | - ((a & ((du_int)(-1) >> ((N + DBL_MANT_DIG+2) - sd))) != 0); - }; - /* finish: */ - a |= (a & 4) != 0; /* Or P into R */ - ++a; /* round - this step may add a significant bit */ - a >>= 2; /* dump Q and R */ - /* a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits */ - if (a & ((du_int)1 << DBL_MANT_DIG)) - { - a >>= 1; - ++e; - } - /* a is now rounded to DBL_MANT_DIG bits */ +COMPILER_RT_ABI double __floatdidf(di_int a) { + if (a == 0) + return 0.0; + const unsigned N = sizeof(di_int) * CHAR_BIT; + const di_int s = a >> (N - 1); + a = (a ^ s) - s; + int sd = N - __builtin_clzll(a); // number of significant digits + int e = sd - 1; // exponent + if (sd > DBL_MANT_DIG) { + // start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx + // finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR + // 12345678901234567890123456 + // 1 = msb 1 bit + // P = bit DBL_MANT_DIG-1 bits to the right of 1 + // Q = bit DBL_MANT_DIG bits to the right of 1 + // R = "or" of all bits to the right of Q + switch (sd) { + case DBL_MANT_DIG + 1: + a <<= 1; + break; + case DBL_MANT_DIG + 2: + break; + default: + a = ((du_int)a >> (sd - (DBL_MANT_DIG + 2))) | + ((a & ((du_int)(-1) >> ((N + DBL_MANT_DIG + 2) - sd))) != 0); + }; + // finish: + a |= (a & 4) != 0; // Or P into R + ++a; // round - this step may add a significant bit + a >>= 2; // dump Q and R + // a is now rounded to DBL_MANT_DIG or DBL_MANT_DIG+1 bits + if (a & ((du_int)1 << DBL_MANT_DIG)) { + a >>= 1; + ++e; } - else - { - a <<= (DBL_MANT_DIG - sd); - /* a is now rounded to DBL_MANT_DIG bits */ - } - double_bits fb; - fb.u.s.high = ((su_int)s & 0x80000000) | /* sign */ - ((e + 1023) << 20) | /* exponent */ - ((su_int)(a >> 32) & 0x000FFFFF); /* mantissa-high */ - fb.u.s.low = (su_int)a; /* mantissa-low */ - return fb.f; + // a is now rounded to DBL_MANT_DIG bits + } else { + a <<= (DBL_MANT_DIG - sd); + // a is now rounded to DBL_MANT_DIG bits + } + double_bits fb; + fb.u.s.high = ((su_int)s & 0x80000000) | // sign + ((e + 1023) << 20) | // exponent + ((su_int)(a >> 32) & 0x000FFFFF); // mantissa-high + fb.u.s.low = (su_int)a; // mantissa-low + return fb.f; } #endif #if defined(__ARM_EABI__) #if defined(COMPILER_RT_ARMHF_TARGET) -AEABI_RTABI double __aeabi_l2d(di_int a) { - return __floatdidf(a); -} +AEABI_RTABI double __aeabi_l2d(di_int a) { return __floatdidf(a); } #else -AEABI_RTABI double __aeabi_l2d(di_int a) COMPILER_RT_ALIAS(__floatdidf); +COMPILER_RT_ALIAS(__floatdidf, __aeabi_l2d) #endif #endif |