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60 lines
1.9 KiB
C++
60 lines
1.9 KiB
C++
//===--- Numeric.cpp - Swift Language ABI numerics support ----------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Implementations of the numeric-support ABI functions.
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//
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//===----------------------------------------------------------------------===//
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#include "swift/Runtime/Numeric.h"
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using namespace swift;
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/// Convert an integer literal to the floating-point type T.
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template <class T>
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static T convert(IntegerLiteral value) {
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using SignedChunk = IntegerLiteral::SignedChunk;
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using UnsignedChunk = IntegerLiteral::UnsignedChunk;
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auto data = value.getData();
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assert(!data.empty() && "always require at least one chunk");
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// The single-word case is the easiest.
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if (data.size() == 1) {
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return T(SignedChunk(data[0]));
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}
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// In two's complement, only the topmost chunk is really signed;
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// everything else is added to that as an unsigned value.
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static_assert(IntegerLiteral::BitsPerChunk == 32 ||
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IntegerLiteral::BitsPerChunk == 64,
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"expected either 32-bit or 64-bit chunking");
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T chunkFactor = (IntegerLiteral::BitsPerChunk == 32 ? 0x1p32 : 0x1p64);
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T result = UnsignedChunk(data[0]);
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T scale = chunkFactor;
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for (size_t i = 1, e = data.size() - 1; i != e; ++i) {
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result += UnsignedChunk(data[i]) * scale;
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scale *= chunkFactor;
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}
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result += SignedChunk(data.back()) * scale;
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return result;
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}
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float swift::swift_intToFloat32(IntegerLiteral value) {
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return convert<float>(value);
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}
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double swift::swift_intToFloat64(IntegerLiteral value) {
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return convert<double>(value);
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}
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