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