diff options
Diffstat (limited to 'lib/builtins/ppc/fixunstfti.c')
| -rw-r--r-- | lib/builtins/ppc/fixunstfti.c | 81 |
1 files changed, 40 insertions, 41 deletions
diff --git a/lib/builtins/ppc/fixunstfti.c b/lib/builtins/ppc/fixunstfti.c index fa21084cb576..1d19e01e3a91 100644 --- a/lib/builtins/ppc/fixunstfti.c +++ b/lib/builtins/ppc/fixunstfti.c @@ -1,9 +1,8 @@ //===-- lib/builtins/ppc/fixunstfti.c - Convert long double->int128 *-C -*-===// // -// 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. +// 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 // //===----------------------------------------------------------------------===// // @@ -15,10 +14,10 @@ #include "../int_math.h" #define BIAS 1023 -/* Convert long double into an unsigned 128-bit integer. */ +// Convert long double into an unsigned 128-bit integer. __uint128_t __fixunstfti(long double input) { - /* If we are trying to convert a NaN, return the NaN bit pattern. */ + // If we are trying to convert a NaN, return the NaN bit pattern. if (crt_isnan(input)) { return ((__uint128_t)0x7FF8000000000000ll) << 64 | (__uint128_t)0x0000000000000000ll; @@ -26,59 +25,59 @@ __uint128_t __fixunstfti(long double input) { __uint128_t result, hiResult, loResult; int hiExponent, loExponent, shift; - /* The long double representation, with the high and low portions of - * the long double, and the corresponding bit patterns of each double. */ + // The long double representation, with the high and low portions of + // the long double, and the corresponding bit patterns of each double. union { long double ld; - double d[2]; /* [0] is the high double, [1] is the low double. */ - unsigned long long ull[2]; /* High and low doubles as 64-bit integers. */ + double d[2]; // [0] is the high double, [1] is the low double. + unsigned long long ull[2]; // High and low doubles as 64-bit integers. } ldUnion; - /* If the long double is less than 1.0 or negative, - * return 0.0. */ + // If the long double is less than 1.0 or negative, + // return 0.0. if (input < 1.0) return 0.0; - /* Retrieve the 64-bit patterns of high and low doubles. - * Compute the unbiased exponent of both high and low doubles by - * removing the signs, isolating the exponent, and subtracting - * the bias from it. */ + // Retrieve the 64-bit patterns of high and low doubles. + // Compute the unbiased exponent of both high and low doubles by + // removing the signs, isolating the exponent, and subtracting + // the bias from it. ldUnion.ld = input; hiExponent = ((ldUnion.ull[0] & 0x7FFFFFFFFFFFFFFFll) >> 52) - BIAS; loExponent = ((ldUnion.ull[1] & 0x7FFFFFFFFFFFFFFFll) >> 52) - BIAS; - /* Convert each double into int64; they will be added to the int128 result. - * CASE 1: High or low double fits in int64 - * - Convert the each double normally into int64. - * - * CASE 2: High or low double does not fit in int64 - * - Scale the double to fit within a 64-bit integer - * - Calculate the shift (amount to scale the double by in the int128) - * - Clear all the bits of the exponent (with 0x800FFFFFFFFFFFFF) - * - Add BIAS+53 (0x4350000000000000) to exponent to correct the value - * - Scale (move) the double to the correct place in the int128 - * (Move it by 2^53 places) - * - * Note: If the high double is assumed to be positive, an unsigned conversion - * from long double to 64-bit integer is needed. The low double can be either - * positive or negative, so a signed conversion is needed to retain the result - * of the low double and to ensure it does not simply get converted to 0. */ + // Convert each double into int64; they will be added to the int128 result. + // CASE 1: High or low double fits in int64 + // - Convert the each double normally into int64. + // + // CASE 2: High or low double does not fit in int64 + // - Scale the double to fit within a 64-bit integer + // - Calculate the shift (amount to scale the double by in the int128) + // - Clear all the bits of the exponent (with 0x800FFFFFFFFFFFFF) + // - Add BIAS+53 (0x4350000000000000) to exponent to correct the value + // - Scale (move) the double to the correct place in the int128 + // (Move it by 2^53 places) + // + // Note: If the high double is assumed to be positive, an unsigned conversion + // from long double to 64-bit integer is needed. The low double can be either + // positive or negative, so a signed conversion is needed to retain the result + // of the low double and to ensure it does not simply get converted to 0. - /* CASE 1 - High double fits in int64. */ + // CASE 1 - High double fits in int64. if (hiExponent < 63) { hiResult = (unsigned long long)ldUnion.d[0]; } else if (hiExponent < 128) { - /* CASE 2 - High double does not fit in int64, scale and convert it. */ + // CASE 2 - High double does not fit in int64, scale and convert it. shift = hiExponent - 54; ldUnion.ull[0] &= 0x800FFFFFFFFFFFFFll; ldUnion.ull[0] |= 0x4350000000000000ll; hiResult = (unsigned long long)ldUnion.d[0]; hiResult <<= shift; } else { - /* Detect cases for overflow. When the exponent of the high - * double is greater than 128 bits and when the long double - * input is positive, return the max 128-bit integer. - * For negative inputs with exponents > 128, return 1, like gcc. */ + // Detect cases for overflow. When the exponent of the high + // double is greater than 128 bits and when the long double + // input is positive, return the max 128-bit integer. + // For negative inputs with exponents > 128, return 1, like gcc. if (ldUnion.d[0] > 0) { return ((__uint128_t)0xFFFFFFFFFFFFFFFFll) << 64 | (__uint128_t)0xFFFFFFFFFFFFFFFFll; @@ -88,11 +87,11 @@ __uint128_t __fixunstfti(long double input) { } } - /* CASE 1 - Low double fits in int64. */ + // CASE 1 - Low double fits in int64. if (loExponent < 63) { loResult = (long long)ldUnion.d[1]; } else { - /* CASE 2 - Low double does not fit in int64, scale and convert it. */ + // CASE 2 - Low double does not fit in int64, scale and convert it. shift = loExponent - 54; ldUnion.ull[1] &= 0x800FFFFFFFFFFFFFll; ldUnion.ull[1] |= 0x4350000000000000ll; @@ -100,7 +99,7 @@ __uint128_t __fixunstfti(long double input) { loResult <<= shift; } - /* Add the high and low doublewords together to form a 128 bit integer. */ + // Add the high and low doublewords together to form a 128 bit integer. result = loResult + hiResult; return result; } |