47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
/* ===-- ashrti3.c - Implement __ashrti3 -----------------------------------===
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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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*
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* This file implements __ashrti3 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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#if __x86_64
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/* Returns: arithmetic a >> b */
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/* Precondition: 0 <= b < bits_in_tword */
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ti_int
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__ashrti3(ti_int a, si_int b)
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{
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const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
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twords input;
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twords result;
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input.all = a;
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if (b & bits_in_dword) /* bits_in_dword <= b < bits_in_tword */
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{
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/* result.s.high = input.s.high < 0 ? -1 : 0 */
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result.s.high = input.s.high >> (bits_in_dword - 1);
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result.s.low = input.s.high >> (b - bits_in_dword);
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}
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else /* 0 <= b < bits_in_dword */
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{
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if (b == 0)
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return a;
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result.s.high = input.s.high >> b;
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result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b);
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}
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return result.all;
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}
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#endif /* __x86_64 */
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