| 1 | //===-- ffsti2.c - Implement __ffsti2 -------------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // This file implements __ffsti2 for the compiler_rt library. |
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| 10 | // |
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| 11 | //===----------------------------------------------------------------------===// |
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| 12 | |
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| 13 | #include "int_lib.h" |
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| 14 | |
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| 15 | #ifdef CRT_HAS_128BIT |
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| 16 | |
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| 17 | // Returns: the index of the least significant 1-bit in a, or |
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| 18 | // the value zero if a is zero. The least significant bit is index one. |
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| 19 | |
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| 20 | COMPILER_RT_ABI int __ffsti2(ti_int a) { |
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| 21 | twords x; |
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| 22 | x.all = a; |
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| 23 | if (x.s.low == 0) { |
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| 24 | if (x.s.high == 0) |
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| 25 | return 0; |
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| 26 | return __builtin_ctzll(x.s.high) + (1 + sizeof(di_int) * CHAR_BIT); |
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| 27 | } |
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| 28 | return __builtin_ctzll(x.s.low) + 1; |
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| 29 | } |
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| 30 | |
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| 31 | #endif // CRT_HAS_128BIT |
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| 32 | |
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