mirror of
https://github.com/xemu-project/xemu.git
synced 2024-11-27 05:20:50 +00:00
e9d07601f6
Addition of div and rem on 128-bit integers, using the 128/64->128 divu and 64x64->128 mulu in host-utils. These operations will be used within div/rem helpers in the 128-bit riscv target. Signed-off-by: Frédéric Pétrot <frederic.petrot@univ-grenoble-alpes.fr> Co-authored-by: Fabien Portas <fabien.portas@grenoble-inp.org> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Message-id: 20220106210108.138226-4-frederic.petrot@univ-grenoble-alpes.fr Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
148 lines
3.7 KiB
C
148 lines
3.7 KiB
C
/*
|
|
* 128-bit division and remainder for compilers not supporting __int128
|
|
*
|
|
* Copyright (c) 2021 Frédéric Pétrot <frederic.petrot@univ-grenoble-alpes.fr>
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include "qemu/host-utils.h"
|
|
#include "qemu/int128.h"
|
|
|
|
#ifndef CONFIG_INT128
|
|
|
|
/*
|
|
* Division and remainder algorithms for 128-bit due to Stefan Kanthak,
|
|
* https://skanthak.homepage.t-online.de/integer.html#udivmodti4
|
|
* Preconditions:
|
|
* - function should never be called with v equals to 0, it has to
|
|
* be dealt with beforehand
|
|
* - quotien pointer must be valid
|
|
*/
|
|
static Int128 divrem128(Int128 u, Int128 v, Int128 *q)
|
|
{
|
|
Int128 qq;
|
|
uint64_t hi, lo, tmp;
|
|
int s = clz64(v.hi);
|
|
|
|
if (s == 64) {
|
|
/* we have uu÷0v => let's use divu128 */
|
|
hi = u.hi;
|
|
lo = u.lo;
|
|
tmp = divu128(&lo, &hi, v.lo);
|
|
*q = int128_make128(lo, hi);
|
|
return int128_make128(tmp, 0);
|
|
} else {
|
|
hi = int128_gethi(int128_lshift(v, s));
|
|
|
|
if (hi > u.hi) {
|
|
lo = u.lo;
|
|
tmp = u.hi;
|
|
divu128(&lo, &tmp, hi);
|
|
lo = int128_gethi(int128_lshift(int128_make128(lo, 0), s));
|
|
} else { /* prevent overflow */
|
|
lo = u.lo;
|
|
tmp = u.hi - hi;
|
|
divu128(&lo, &tmp, hi);
|
|
lo = int128_gethi(int128_lshift(int128_make128(lo, 1), s));
|
|
}
|
|
|
|
qq = int128_make64(lo);
|
|
|
|
tmp = lo * v.hi;
|
|
mulu64(&lo, &hi, lo, v.lo);
|
|
hi += tmp;
|
|
|
|
if (hi < tmp /* quotient * divisor >= 2**128 > dividend */
|
|
|| hi > u.hi /* quotient * divisor > dividend */
|
|
|| (hi == u.hi && lo > u.lo)) {
|
|
qq.lo -= 1;
|
|
mulu64(&lo, &hi, qq.lo, v.lo);
|
|
hi += qq.lo * v.hi;
|
|
}
|
|
|
|
*q = qq;
|
|
u.hi -= hi + (u.lo < lo);
|
|
u.lo -= lo;
|
|
return u;
|
|
}
|
|
}
|
|
|
|
Int128 int128_divu(Int128 a, Int128 b)
|
|
{
|
|
Int128 q;
|
|
divrem128(a, b, &q);
|
|
return q;
|
|
}
|
|
|
|
Int128 int128_remu(Int128 a, Int128 b)
|
|
{
|
|
Int128 q;
|
|
return divrem128(a, b, &q);
|
|
}
|
|
|
|
Int128 int128_divs(Int128 a, Int128 b)
|
|
{
|
|
Int128 q;
|
|
bool sgna = !int128_nonneg(a);
|
|
bool sgnb = !int128_nonneg(b);
|
|
|
|
if (sgna) {
|
|
a = int128_neg(a);
|
|
}
|
|
|
|
if (sgnb) {
|
|
b = int128_neg(b);
|
|
}
|
|
|
|
divrem128(a, b, &q);
|
|
|
|
if (sgna != sgnb) {
|
|
q = int128_neg(q);
|
|
}
|
|
|
|
return q;
|
|
}
|
|
|
|
Int128 int128_rems(Int128 a, Int128 b)
|
|
{
|
|
Int128 q, r;
|
|
bool sgna = !int128_nonneg(a);
|
|
bool sgnb = !int128_nonneg(b);
|
|
|
|
if (sgna) {
|
|
a = int128_neg(a);
|
|
}
|
|
|
|
if (sgnb) {
|
|
b = int128_neg(b);
|
|
}
|
|
|
|
r = divrem128(a, b, &q);
|
|
|
|
if (sgna) {
|
|
r = int128_neg(r);
|
|
}
|
|
|
|
return r;
|
|
}
|
|
|
|
#endif
|