common/static_assert.h

/******************************************************************************
 * @file     static_assert.h
 *
 * @brief    for TLSR chips
 *
 * @author   public@telink-semi.com;
 * @date     Sep. 30, 2010
 *
 * @attention
 *
 *  Copyright (C) 2019-2020 Telink Semiconductor (Shanghai) Co., Ltd.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *****************************************************************************/

#pragma once

// static assertion. evaluate at compile time. It is very useful like,  STATIC_ASSERT(sizeof(a) == 5);

// #define STATIC_ASSERT(expr)               { char static_assertion[(expr) ? 1 : -1]; ((void) static_assertion); }    // (void) array;  to remove compiler unused variable warning

// more complicated version canbe used anywhere in the source
#define STATIC_ASSERT_M(COND,MSG) typedef char static_assertion_##MSG[(!!(COND))*2-1]
// token pasting madness:
#define STATIC_ASSERT3(X,L)     STATIC_ASSERT_M(X,static_assertion_at_line_##L)
#define STATIC_ASSERT2(X,L)     STATIC_ASSERT3(X,L)

#define STATIC_ASSERT(X)        STATIC_ASSERT2(X,__LINE__)

#define STATIC_ASSERT_POW2(expr)        STATIC_ASSERT(!((expr) & ((expr)-1)))                    //  assert  expr  is  2**N
#define STATIC_ASSERT_EVEN(expr)        STATIC_ASSERT(!((expr) & 1))
#define STATIC_ASSERT_ODD(expr)         STATIC_ASSERT(((expr) & 1))
#define STATIC_ASSERT_INT_DIV(a, b)     STATIC_ASSERT((a) / (b) * (b) == (a))