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73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see the file COPYING, or write
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* to the Free Software Foundation, Inc.
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*/
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#include <linux/export.h>
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#include <lib/libgcc.h>
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#define W_TYPE_SIZE 32
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#define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
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#define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
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#define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))
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/* If we still don't have umul_ppmm, define it using plain C. */
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#if !defined(umul_ppmm)
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#define umul_ppmm(w1, w0, u, v) \
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do { \
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unsigned long __x0, __x1, __x2, __x3; \
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unsigned short __ul, __vl, __uh, __vh; \
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\
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__ul = __ll_lowpart(u); \
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__uh = __ll_highpart(u); \
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__vl = __ll_lowpart(v); \
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__vh = __ll_highpart(v); \
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\
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__x0 = (unsigned long) __ul * __vl; \
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__x1 = (unsigned long) __ul * __vh; \
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__x2 = (unsigned long) __uh * __vl; \
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__x3 = (unsigned long) __uh * __vh; \
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\
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__x1 += __ll_highpart(__x0); /* this can't give carry */\
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__x1 += __x2; /* but this indeed can */ \
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if (__x1 < __x2) /* did we get it? */ \
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__x3 += __ll_B; /* yes, add it in the proper pos */ \
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\
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(w1) = __x3 + __ll_highpart(__x1); \
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(w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
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} while (0)
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#endif
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#if !defined(__umulsidi3)
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#define __umulsidi3(u, v) ({ \
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DWunion __w; \
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umul_ppmm(__w.s.high, __w.s.low, u, v); \
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__w.ll; \
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})
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#endif
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long long notrace __muldi3(long long u, long long 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 = {.ll = __umulsidi3(uu.s.low, vv.s.low)};
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w.s.high += ((unsigned long) uu.s.low * (unsigned long) vv.s.high
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+ (unsigned long) uu.s.high * (unsigned long) vv.s.low);
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return w.ll;
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}
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EXPORT_SYMBOL(__muldi3);
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