__udivmoddi4.c

来自「linux内核」· C语言 代码 · 共 32 行

#include <stdint.h>

uint64_t __udivmoddi4(uint64_t num, uint64_t den, uint64_t *rem_p)
{
  uint64_t quot = 0, qbit = 1;
  
  if ( den == 0 ) {
    asm volatile("int $0");
    return 0;			/* If trap returns... */
  }

  /* Left-justify denominator and count shift */
  while ( (int64_t)den >= 0 ) {
    den <<= 1;
    qbit <<= 1;
  }

  while ( qbit ) {
    if ( den <= num ) {
      num -= den;
      quot += qbit;
    }
    den >>= 1;
    qbit >>= 1;
  }

  if ( rem_p )
    *rem_p = num;

  return quot;
}