C Saturating Signed and Unsigned Functions

satlib.h

/**
* Copyright 2021 Lucas Orsi (lorsi)
* 
* Redistribution and use in source and binary forms, with or without modification, 
* are permitted provided that the following conditions are met:
* 
* 1. Redistributions of source code must retain the above copyright notice, this 
*    list of conditions and the following disclaimer.
* 
* 2. 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.
* 
* 3. Neither the name of the copyright holder 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 HOLDER 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 <stdint.h>

#define DECL_ADD(XX) uint##XX##_t add##XX (uint##XX##_t a, uint##XX##_t b) {\
                        uint##XX##_t c = a + b; \
                        return c < a ? UINT##XX##_MAX : c;};

#define DECL_SUB(XX) uint##XX## _t sub##XX (uint##XX##_t a, uint##XX##_t b) {\
                        uint##XX##_t c = a - b; \
                        return c > a ? 0 : c;};

#define DECL_SADD(XX) int ##XX##_t sadd##XX (int ##XX##_t a, int ##XX##_t b) { \
    int##XX##_t c = a + b; \
    return ((a ^ b) & INT##XX##_MIN) == 0 ? (c ^ a) & INT##XX##_MIN ? (a < 0) ? INT##XX##_MIN : INT##XX##_MAX : c : c; \
}

#define DECL_SSUB(XX) int ##XX##_t ssub##XX (int##XX##_t a, int##XX##_t b) { \
    int##XX## _t c = a - b; \
    return ((a ^ b) & INT##XX##_MIN) == 0 ? (c ^ a) & INT##XX##_MIN ? (a < 0) ? INT##XX##_MIN : INT##XX##_MAX : c : c; \
}


DECL_ADD(8);  // uint8_t add8(uint8_t, uint8_t);
DECL_ADD(16); // uint16_t add8(uint16_t, uint16_t);
DECL_ADD(32);

DECL_SUB(8);
DECL_SUB(16);
DECL_SUB(32);

DECL_SADD(8); // int8_t sadd8(int8_t, int8_t);
DECL_SADD(16);
DECL_SADD(32);

DECL_SSUB(8);
DECL_SSUB(16); // int16_t ssub16(int16_t, int16_t);
DECL_SSUB(32);