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/* ----------------------------------------------------------------------- *
*
* Copyright 1996-2010 The NASM Authors - All Rights Reserved
* See the file AUTHORS included with the NASM distribution for
* the specific copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following
* conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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 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 OWNER 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 "compiler.h"
#include "nasmlib.h"
#define ROUND(v, a, w) \
do { \
if (v & (((1 << w) - 1) << w)) { \
a += w; \
v >>= w; \
} \
} while (0)
#if defined(__GNUC__) && defined(__x86_64__)
int ilog2_32(uint32_t v)
{
int n;
__asm__("bsrl %1,%0"
: "=r" (n)
: "rm" (v), "0" (0));
return n;
}
#elif defined(__GNUC__) && defined(__i386__)
int ilog2_32(uint32_t v)
{
int n;
__asm__("bsrl %1,%0 ; jnz 1f ; xorl %0,%0\n"
"1:"
: "=&r" (n)
: "rm" (v));
return n;
}
#elif defined(HAVE_GNUC_4)
int ilog2_32(uint32_t v)
{
if (!v)
return 0;
return __builtin_clz(v) ^ 31;
}
#else
int ilog2_32(uint32_t v)
{
int p = 0;
ROUND(v, p, 16);
ROUND(v, p, 8);
ROUND(v, p, 4);
ROUND(v, p, 2);
ROUND(v, p, 1);
return p;
}
#endif
#if defined(__GNUC__) && defined(__x86_64__)
int ilog2_64(uint64_t v)
{
uint64_t n;
__asm__("bsrq %1,%0"
: "=r" (n)
: "rm" (v), "0" (UINT64_C(0)));
return n;
}
#elif defined(HAVE_GNUC_4)
int ilog2_64(uint64_t v)
{
if (!v)
return 0;
return __builtin_clzll(v) ^ 63;
}
#else
int ilog2_64(uint64_t vv)
{
int p = 0;
uint32_t v;
v = vv >> 32;
if (v)
p += 32;
else
v = vv;
ROUND(v, p, 16);
ROUND(v, p, 8);
ROUND(v, p, 4);
ROUND(v, p, 2);
ROUND(v, p, 1);
return p;
}
#endif
/*
* v == 0 ? 0 : is_power2(x) ? ilog2_X(v) : -1
*/
int alignlog2_32(uint32_t v)
{
if (unlikely(v & (v-1)))
return -1; /* invalid alignment */
return ilog2_32(v);
}
int alignlog2_64(uint64_t v)
{
if (unlikely(v & (v-1)))
return -1; /* invalid alignment */
return ilog2_64(v);
}
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