bits.h

// vim: ts=4:sw=4:expandtab:
/*
 * Copyright (c) 2013-2014 Travis Geiselbrecht
 *
 * 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.
 */
#pragma once

/* bit manipulation macros */
#define BIT(x, bit) ((x) & (1 << (bit)))
#define BIT_SHIFT(x, bit) (((x) >> (bit)) & 1)
#define BITS(x, high, low) ((x) & (((1<<((high)+1))-1) & ~((1<<(low))-1)))
#define BITS_SHIFT(x, high, low) (((x) >> (low)) & ((1<<((high)-(low)+1))-1))
#define BIT_SET(x, bit) (((x) & (1 << (bit))) ? 1 : 0)

#define ISNEG(x) BIT((x), 31)
#define ISPOS(x) (!(BIT(x, 31)))

static inline int SignExtend(uint32_t in, unsigned int pos) {
    if (!BIT(in, pos)) {
        return in;
    } else {
        return ((int)in << (31 - pos)) >> (31 - pos);
    }
}

static inline int SignExtend(uint8_t in) {
    return SignExtend((uint32_t)in, 7);
}

static inline int SignExtend(uint16_t in) {
    return SignExtend((uint32_t)in, 15);
}