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- /* Multiplication two double word integers for RISC-V.
- Copyright (C) 2016-2022 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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