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/* ===-- udivsi3.c - Implement __udivsi3 -----------------------------------===
*
* The LLVM Compiler Infrastructure
*
* This file is dual licensed under the MIT and the University of Illinois Open
* Source Licenses. See LICENSE.TXT for details.
*
* ===----------------------------------------------------------------------===
*
* This file implements __udivsi3 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "int_lib.h"
/* Returns: a / b */
/* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */
ARM_EABI_FNALIAS(uidiv, udivsi3)
/* This function should not call __divsi3! */
COMPILER_RT_ABI su_int
__udivsi3(su_int n, su_int d)
{
const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
su_int q;
su_int r;
unsigned sr;
/* special cases */
if (d == 0)
return 0; /* ?! */
if (n == 0)
return 0;
sr = __builtin_clz(d) - __builtin_clz(n);
/* 0 <= sr <= n_uword_bits - 1 or sr large */
if (sr > n_uword_bits - 1) /* d > r */
return 0;
if (sr == n_uword_bits - 1) /* d == 1 */
return n;
++sr;
/* 1 <= sr <= n_uword_bits - 1 */
/* Not a special case */
q = n << (n_uword_bits - sr);
r = n >> sr;
su_int carry = 0;
for (; sr > 0; --sr)
{
/* r:q = ((r:q) << 1) | carry */
r = (r << 1) | (q >> (n_uword_bits - 1));
q = (q << 1) | carry;
/* carry = 0;
* if (r.all >= d.all)
* {
* r.all -= d.all;
* carry = 1;
* }
*/
const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1);
carry = s & 1;
r -= d & s;
}
q = (q << 1) | carry;
return q;
}
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