div64.c

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#include <xwos/standard.h>
#include <xwos/lib/div64.h>
 
static __xwlib_code
xwu32_t xwdiv64_32(xwu64_t * dividend, xwu32_t divisor);
 
__xwlib_code
xwu32_t xwdiv64(xwu64_t * n, xwu32_t divisor)
{
        xwu32_t rem;
        if (((*n) >> (xwu32_t)32) == (xwu32_t)0) {
                rem = (xwu32_t)(*n) % divisor;
                *n = (*n) / (xwu64_t)divisor;
        } else {
                rem = xwdiv64_32(n, divisor);
        }
        return rem;
}
 
static __xwlib_code
xwu32_t xwdiv64_32(xwu64_t * n, xwu32_t divisor)
{
        xwu64_t rem = *n;
        xwu64_t b = divisor;
        xwu64_t res;
        xwu64_t d = (xwu64_t)1;
        xwu32_t high = (xwu32_t)(rem >> (xwu32_t)32);
 
        res = 0;
        if (high >= divisor) {
                high /= divisor;
                res = (xwu64_t)high << (xwu64_t)32;
                rem -= (((xwu64_t)high * (xwu64_t)divisor) << (xwu64_t)32);
        }
 
        while (((xws64_t)b > (xws64_t)0) && (b < rem)) {
                b = b + b;
                d = d + d;
        }
 
        do {
                if (rem >= b) {
                        rem -= b;
                        res += d;
                }
                b >>= (xwu64_t)1;
                d >>= (xwu64_t)1;
        } while ((xwu64_t)0 != d);
 
        *n = res;
        return (xwu32_t)rem;
}