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87 lines
2.3 KiB
C
87 lines
2.3 KiB
C
/* Multiplication two double word integers for RISC-V.
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Copyright (C) 2016-2020 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "tconfig.h"
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#include "tsystem.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "libgcc_tm.h"
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#define LIBGCC2_UNITS_PER_WORD (__riscv_xlen / 8)
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#include "libgcc2.h"
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#if __riscv_xlen == 32
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/* Our RV64 64-bit routines are equivalent to our RV32 32-bit routines. */
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# define __multi3 __muldi3
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#endif
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DWtype
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__multi3 (DWtype u, DWtype v)
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{
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const DWunion uu = {.ll = u};
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const DWunion vv = {.ll = v};
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DWunion w;
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UWtype u_low = uu.s.low;
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UWtype v_low = vv.s.low;
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UWtype u_low_msb;
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UWtype w_low = 0;
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UWtype new_w_low;
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UWtype w_high = 0;
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UWtype w_high_tmp = 0;
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UWtype w_high_tmp2x;
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UWtype carry;
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/* Calculate low half part of u and v, and get a UDWtype result just like
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what __umulsidi3 do. */
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do
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{
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new_w_low = w_low + u_low;
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w_high_tmp2x = w_high_tmp << 1;
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w_high_tmp += w_high;
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if (v_low & 1)
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{
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carry = new_w_low < w_low;
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w_low = new_w_low;
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w_high = carry + w_high_tmp;
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}
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u_low_msb = (u_low >> ((sizeof (UWtype) * 8) - 1));
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v_low >>= 1;
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u_low <<= 1;
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w_high_tmp = u_low_msb | w_high_tmp2x;
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}
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while (v_low);
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w.s.low = w_low;
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w.s.high = w_high;
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if (uu.s.high)
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w.s.high = w.s.high + __muluw3(vv.s.low, uu.s.high);
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if (vv.s.high)
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w.s.high += __muluw3(uu.s.low, vv.s.high);
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return w.ll;
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}
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