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/* Multiplication two double word integers for RISC-V.
Copyright (C) 2016-2019 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "tconfig.h"
#include "tsystem.h"
#include "coretypes.h"
#include "tm.h"
#include "libgcc_tm.h"
#define LIBGCC2_UNITS_PER_WORD (__riscv_xlen / 8)
#include "libgcc2.h"
#if __riscv_xlen == 32
/* Our RV64 64-bit routines are equivalent to our RV32 32-bit routines. */
# define __multi3 __muldi3
#endif
DWtype
__multi3 (DWtype u, DWtype v)
{
const DWunion uu = {.ll = u};
const DWunion vv = {.ll = v};
DWunion w;
UWtype u_low = uu.s.low;
UWtype v_low = vv.s.low;
UWtype u_low_msb;
UWtype w_low = 0;
UWtype new_w_low;
UWtype w_high = 0;
UWtype w_high_tmp = 0;
UWtype w_high_tmp2x;
UWtype carry;
/* Calculate low half part of u and v, and get a UDWtype result just like
what __umulsidi3 do. */
do
{
new_w_low = w_low + u_low;
w_high_tmp2x = w_high_tmp << 1;
w_high_tmp += w_high;
if (v_low & 1)
{
carry = new_w_low < w_low;
w_low = new_w_low;
w_high = carry + w_high_tmp;
}
u_low_msb = (u_low >> ((sizeof (UWtype) * 8) - 1));
v_low >>= 1;
u_low <<= 1;
w_high_tmp = u_low_msb | w_high_tmp2x;
}
while (v_low);
w.s.low = w_low;
w.s.high = w_high;
if (uu.s.high)
w.s.high = w.s.high + __muluw3(vv.s.low, uu.s.high);
if (vv.s.high)
w.s.high += __muluw3(uu.s.low, vv.s.high);
return w.ll;
}
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