// SPDX-License-Identifier: GPL-2.0-or-later
/*
 */

#include <linux/export.h>
#include <linux/libgcc.h>

#define W_TYPE_SIZE 32

#define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
#define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
#define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))

/* If we still don't have umul_ppmm, define it using plain C.  */
#if !defined(umul_ppmm)
#define umul_ppmm(w1, w0, u, v)                                         \
        do {                                                            \
                unsigned long __x0, __x1, __x2, __x3;                   \
                unsigned short __ul, __vl, __uh, __vh;                  \
                                                                        \
                __ul = __ll_lowpart(u);                                 \
                __uh = __ll_highpart(u);                                \
                __vl = __ll_lowpart(v);                                 \
                __vh = __ll_highpart(v);                                \
                                                                        \
                __x0 = (unsigned long) __ul * __vl;                     \
                __x1 = (unsigned long) __ul * __vh;                     \
                __x2 = (unsigned long) __uh * __vl;                     \
                __x3 = (unsigned long) __uh * __vh;                     \
                                                                        \
                __x1 += __ll_highpart(__x0); /* this can't give carry */\
                __x1 += __x2; /* but this indeed can */                 \
                if (__x1 < __x2) /* did we get it? */                   \
                __x3 += __ll_B; /* yes, add it in the proper pos */     \
                                                                        \
                (w1) = __x3 + __ll_highpart(__x1);                      \
                (w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
        } while (0)
#endif

#if !defined(__umulsidi3)
#define __umulsidi3(u, v) ({                            \
        DWunion __w;                                    \
        umul_ppmm(__w.s.high, __w.s.low, u, v);         \
        __w.ll;                                         \
        })
#endif

long long notrace __muldi3(long long u, long long v)
{
        const DWunion uu = {.ll = u};
        const DWunion vv = {.ll = v};
        DWunion w = {.ll = __umulsidi3(uu.s.low, vv.s.low)};

        w.s.high += ((unsigned long) uu.s.low * (unsigned long) vv.s.high
                + (unsigned long) uu.s.high * (unsigned long) vv.s.low);

        return w.ll;
}
EXPORT_SYMBOL(__muldi3);