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/* ===-- multi3.c - Implement __multi3 -------------------------------------=== |
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* |
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* The LLVM Compiler Infrastructure |
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* |
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* This file is dual licensed under the MIT and the University of Illinois Open |
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* Source Licenses. See LICENSE.TXT for details. |
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* |
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* ===----------------------------------------------------------------------=== |
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* This file implements __multi3 for the compiler_rt library. |
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* |
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* ===----------------------------------------------------------------------=== |
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*/ |
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#include "int_lib.h" |
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#ifdef CRT_HAS_128BIT |
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/* Returns: a * b */ |
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static |
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ti_int |
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__mulddi3(du_int a, du_int b) |
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{ |
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twords r; |
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const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2; |
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const du_int lower_mask = (du_int)~0 >> bits_in_dword_2; |
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r.s.low = (a & lower_mask) * (b & lower_mask); |
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du_int t = r.s.low >> bits_in_dword_2; |
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r.s.low &= lower_mask; |
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t += (a >> bits_in_dword_2) * (b & lower_mask); |
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r.s.low += (t & lower_mask) << bits_in_dword_2; |
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r.s.high = t >> bits_in_dword_2; |
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t = r.s.low >> bits_in_dword_2; |
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r.s.low &= lower_mask; |
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t += (b >> bits_in_dword_2) * (a & lower_mask); |
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r.s.low += (t & lower_mask) << bits_in_dword_2; |
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r.s.high += t >> bits_in_dword_2; |
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r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2); |
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return r.all; |
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} |
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/* Returns: a * b */ |
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COMPILER_RT_ABI ti_int |
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__multi3(ti_int a, ti_int b) |
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{ |
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twords x; |
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x.all = a; |
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twords y; |
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y.all = b; |
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twords r; |
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r.all = __mulddi3(x.s.low, y.s.low); |
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r.s.high += x.s.high * y.s.low + x.s.low * y.s.high; |
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return r.all; |
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} |
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#endif /* CRT_HAS_128BIT */ |