55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
/* ===-- muldi3.c - Implement __muldi3 -------------------------------------===
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*
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* The LLVM Compiler Infrastructure
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*
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* This file is distributed under the University of Illinois Open Source
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* License. See LICENSE.TXT for details.
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*
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* ===----------------------------------------------------------------------===
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*
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* This file implements __muldi3 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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/* Returns: a * b */
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static
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di_int
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__muldsi3(su_int a, su_int b)
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{
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dwords r;
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const int bits_in_word_2 = (int)(sizeof(si_int) * CHAR_BIT) / 2;
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const su_int lower_mask = (su_int)~0 >> bits_in_word_2;
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r.s.low = (a & lower_mask) * (b & lower_mask);
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su_int t = r.s.low >> bits_in_word_2;
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r.s.low &= lower_mask;
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t += (a >> bits_in_word_2) * (b & lower_mask);
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r.s.low += (t & lower_mask) << bits_in_word_2;
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r.s.high = t >> bits_in_word_2;
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t = r.s.low >> bits_in_word_2;
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r.s.low &= lower_mask;
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t += (b >> bits_in_word_2) * (a & lower_mask);
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r.s.low += (t & lower_mask) << bits_in_word_2;
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r.s.high += t >> bits_in_word_2;
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r.s.high += (a >> bits_in_word_2) * (b >> bits_in_word_2);
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return r.all;
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}
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/* Returns: a * b */
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di_int
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__muldi3(di_int a, di_int b)
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{
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dwords x;
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x.all = a;
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dwords y;
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y.all = b;
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dwords r;
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r.all = __muldsi3(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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