137 lines
4.1 KiB
C
137 lines
4.1 KiB
C
/*
|
|
* Copyright (C) 2018 Intel Corporation. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* * Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* * Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* * Neither the name of Intel Corporation nor the names of its
|
|
* contributors may be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <hv_lib.h>
|
|
|
|
static int do_udiv32(uint32_t dividend, uint32_t divisor,
|
|
struct udiv_result *res)
|
|
{
|
|
|
|
uint32_t mask;
|
|
/* dividend is always greater than or equal to the divisor. Neither
|
|
* divisor nor dividend are 0. Thus: * clz(dividend) and clz(divisor)
|
|
* are valid * clz(dividend)<=clz(divisor)
|
|
*/
|
|
|
|
mask = clz(divisor) - clz(dividend);
|
|
/* align divisor and dividend */
|
|
divisor <<= mask;
|
|
mask = 1U << mask;
|
|
/* division loop */
|
|
do {
|
|
if (dividend >= divisor) {
|
|
dividend -= divisor;
|
|
res->q.dwords.low |= mask;
|
|
}
|
|
divisor >>= 1;
|
|
} while (((mask >>= 1) != 0) && (dividend != 0));
|
|
/* dividend now contains the reminder */
|
|
res->r.dwords.low = dividend;
|
|
return 0;
|
|
}
|
|
|
|
int udiv32(uint32_t dividend, uint32_t divisor, struct udiv_result *res)
|
|
{
|
|
|
|
/* initialize the result */
|
|
res->q.dwords.low = res->r.dwords.low = 0;
|
|
/* test for "division by 0" condition */
|
|
if (divisor == 0) {
|
|
res->q.dwords.low = 0xffffffff;
|
|
return !0;
|
|
}
|
|
/* trivial case: divisor==dividend */
|
|
if (divisor == dividend) {
|
|
res->q.dwords.low = 1;
|
|
return 0;
|
|
}
|
|
/* trivial case: divisor>dividend */
|
|
if (divisor > dividend) {
|
|
res->r.dwords.low = dividend;
|
|
return 0;
|
|
}
|
|
/* now that the trivial cases are eliminated we can call the generic
|
|
* function.
|
|
*/
|
|
return do_udiv32(dividend, divisor, res);
|
|
}
|
|
|
|
int udiv64(uint64_t dividend, uint64_t divisor, struct udiv_result *res)
|
|
{
|
|
|
|
uint64_t mask;
|
|
uint64_t bits;
|
|
|
|
/* initialize the result */
|
|
res->q.qword = res->r.qword = 0;
|
|
/* test for "division by 0" condition */
|
|
if (divisor == 0) {
|
|
res->q.qword = 0xffffffffffffffffull;
|
|
return -1;
|
|
}
|
|
/* trivial case: divisor==dividend */
|
|
if (divisor == dividend) {
|
|
res->q.qword = 1;
|
|
return 0;
|
|
}
|
|
/* trivial case: divisor>dividend */
|
|
if (divisor > dividend) {
|
|
res->r.qword = dividend;
|
|
return 0;
|
|
}
|
|
/* simplified case: only 32 bit operands Note that the preconditions
|
|
* for do_udiv32() are fulfilled, since the tests were made above.
|
|
*/
|
|
if (((divisor >> 32) == 0) && ((dividend >> 32) == 0))
|
|
return do_udiv32((uint32_t) dividend, (uint32_t) divisor, res);
|
|
|
|
/* dividend is always greater than or equal to the divisor. Neither
|
|
* divisor nor dividend are 0. Thus: * clz(dividend) and clz(divisor)
|
|
* are valid * clz(dividend)<=clz(divisor)
|
|
*/
|
|
|
|
/* align divisor and dividend. */
|
|
bits = clz64(divisor) - clz64(dividend);
|
|
divisor <<= bits;
|
|
mask = 1ULL << bits;
|
|
/* division loop */
|
|
do {
|
|
if (dividend >= divisor) {
|
|
dividend -= divisor;
|
|
res->q.qword |= mask;
|
|
}
|
|
divisor >>= 1;
|
|
mask >>= 1;
|
|
} while ((bits-- != 0) && (dividend != 0));
|
|
|
|
res->r.qword = dividend;
|
|
return 0;
|
|
}
|