mirror of
https://github.com/projectacrn/acrn-hypervisor.git
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91337da5a1
Added brackets for expression to make it easy to understand and reduce the mistake of precedence. The rule is applied to the mixed same level of prevedence opeartors, high level presedence operators and logical expression. Signed-off-by: Yang, Yu-chu <yu-chu.yang@intel.com> Acked-by: Anthony Xu <anthony.xu@intel.com>
117 lines
2.7 KiB
C
117 lines
2.7 KiB
C
/*
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* Copyright (C) 2018 Intel Corporation. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <hv_lib.h>
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static int do_udiv32(uint32_t dividend, uint32_t divisor,
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struct udiv_result *res)
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{
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uint32_t mask;
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/* dividend is always greater than or equal to the divisor. Neither
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* divisor nor dividend are 0. Thus: * clz(dividend) and clz(divisor)
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* are valid * clz(dividend)<=clz(divisor)
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*/
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mask = (uint32_t)(clz(divisor) - clz(dividend));
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/* align divisor and dividend */
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divisor <<= mask;
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mask = 1U << mask;
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/* division loop */
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do {
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if (dividend >= divisor) {
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dividend -= divisor;
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res->q.dwords.low |= mask;
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}
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divisor >>= 1U;
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mask >>= 1U;
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} while ((mask != 0U) && (dividend != 0U));
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/* dividend now contains the reminder */
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res->r.dwords.low = dividend;
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return 0;
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}
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int udiv32(uint32_t dividend, uint32_t divisor, struct udiv_result *res)
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{
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/* initialize the result */
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res->q.dwords.low = 0U;
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res->r.dwords.low = 0U;
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/* test for "division by 0" condition */
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if (divisor == 0U) {
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res->q.dwords.low = 0xffffffffU;
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return 1;
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}
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/* trivial case: divisor==dividend */
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if (divisor == dividend) {
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res->q.dwords.low = 1U;
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return 0;
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}
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/* trivial case: divisor>dividend */
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if (divisor > dividend) {
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res->r.dwords.low = dividend;
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return 0;
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}
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/* now that the trivial cases are eliminated we can call the generic
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* function.
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*/
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return do_udiv32(dividend, divisor, res);
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}
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int udiv64(uint64_t dividend, uint64_t divisor, struct udiv_result *res)
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{
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uint64_t mask;
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uint64_t bits;
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/* initialize the result */
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res->q.qword = 0UL;
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res->r.qword = 0UL;
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/* test for "division by 0" condition */
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if (divisor == 0UL) {
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res->q.qword = 0xffffffffffffffffUL;
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return -1;
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}
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/* trivial case: divisor==dividend */
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if (divisor == dividend) {
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res->q.qword = 1UL;
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return 0;
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}
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/* trivial case: divisor>dividend */
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if (divisor > dividend) {
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res->r.qword = dividend;
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return 0;
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}
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/* simplified case: only 32 bit operands Note that the preconditions
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* for do_udiv32() are fulfilled, since the tests were made above.
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*/
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if (((divisor >> 32UL) == 0UL) && ((dividend >> 32UL) == 0UL)) {
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return do_udiv32((uint32_t) dividend, (uint32_t) divisor, res);
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}
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/* dividend is always greater than or equal to the divisor. Neither
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* divisor nor dividend are 0. Thus: * clz(dividend) and clz(divisor)
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* are valid * clz(dividend)<=clz(divisor)
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*/
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/* align divisor and dividend. */
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bits = (uint64_t)(clz64(divisor) - clz64(dividend));
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divisor <<= bits;
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mask = 1UL << bits;
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/* division loop */
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do {
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if (dividend >= divisor) {
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dividend -= divisor;
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res->q.qword |= mask;
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}
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divisor >>= 1UL;
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mask >>= 1UL;
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} while (((bits--) != 0UL) && (dividend != 0UL));
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res->r.qword = dividend;
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return 0;
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}
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