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mbin_swm.c
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mbin_swm.c
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/*-
* Copyright (c) 2010 Hans Petter Selasky
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
/*
* mbin_swm_xxx() - shift with mask functions.
*/
#include <stdint.h>
#include "math_bin.h"
uint32_t
mbin_swm32(uint32_t x, uint32_t m, int8_t count)
{
if (count < 0) {
/* unfortunately there is no reverse addition */
x = mbin_bitrev32(x);
m = mbin_bitrev32(m);
while (count < 0) {
x = ((~m & x) | (m & ((~m) + (2 * (m & x)))));
count++;
}
x = mbin_bitrev32(x);
} else {
while (count > 0) {
x = ((~m & x) | (m & ((~m) + (2 * (m & x)))));
count--;
}
}
return (x);
}