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/*
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* This program is free software and is provided to you under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation, and any use by you of this program is subject to the terms of such GNU licence.
*
* A copy of the licence is included with the program, and can also be obtained from Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/**
* @file mali_osk_bitops.h
* Implementation of the OS abstraction layer for the kernel device driver
*/
#ifndef __MALI_OSK_BITOPS_H__
#define __MALI_OSK_BITOPS_H__
#ifdef __cplusplus
extern "C"
{
#endif
MALI_STATIC_INLINE void _mali_internal_clear_bit( u32 bit, u32 *addr )
{
MALI_DEBUG_ASSERT( bit < 32 );
MALI_DEBUG_ASSERT( NULL != addr );
(*addr) &= ~(1 << bit);
}
MALI_STATIC_INLINE void _mali_internal_set_bit( u32 bit, u32 *addr )
{
MALI_DEBUG_ASSERT( bit < 32 );
MALI_DEBUG_ASSERT( NULL != addr );
(*addr) |= (1 << bit);
}
MALI_STATIC_INLINE u32 _mali_internal_test_bit( u32 bit, u32 value )
{
MALI_DEBUG_ASSERT( bit < 32 );
return value & (1 << bit);
}
MALI_STATIC_INLINE int _mali_internal_find_first_zero_bit( u32 value )
{
u32 inverted;
u32 negated;
u32 isolated;
u32 leading_zeros;
/* Begin with xxx...x0yyy...y, where ys are 1, number of ys is in range 0..31 */
inverted = ~value; /* zzz...z1000...0 */
/* Using count_trailing_zeros on inverted value -
* See ARM System Developers Guide for details of count_trailing_zeros */
/* Isolate the zero: it is preceeded by a run of 1s, so add 1 to it */
negated = (u32)-inverted ; /* -a == ~a + 1 (mod 2^n) for n-bit numbers */
/* negated = xxx...x1000...0 */
isolated = negated & inverted ; /* xxx...x1000...0 & zzz...z1000...0, zs are ~xs */
/* And so the first zero bit is in the same position as the 1 == number of 1s that preceeded it
* Note that the output is zero if value was all 1s */
leading_zeros = _mali_osk_clz( isolated );
return 31 - leading_zeros;
}
/** @defgroup _mali_osk_bitops OSK Non-atomic Bit-operations
* @{ */
/**
* These bit-operations do not work atomically, and so locks must be used if
* atomicity is required.
*
* Reference implementations for Little Endian are provided, and so it should
* not normally be necessary to re-implement these. Efficient bit-twiddling
* techniques are used where possible, implemented in portable C.
*
* Note that these reference implementations rely on _mali_osk_clz() being
* implemented.
*/
/** @brief Clear a bit in a sequence of 32-bit words
* @param nr bit number to clear, starting from the (Little-endian) least
* significant bit
* @param addr starting point for counting.
*/
MALI_STATIC_INLINE void _mali_osk_clear_nonatomic_bit( u32 nr, u32 *addr )
{
addr += nr >> 5; /* find the correct word */
nr = nr & ((1 << 5)-1); /* The bit number within the word */
_mali_internal_clear_bit( nr, addr );
}
/** @brief Set a bit in a sequence of 32-bit words
* @param nr bit number to set, starting from the (Little-endian) least
* significant bit
* @param addr starting point for counting.
*/
MALI_STATIC_INLINE void _mali_osk_set_nonatomic_bit( u32 nr, u32 *addr )
{
addr += nr >> 5; /* find the correct word */
nr = nr & ((1 << 5)-1); /* The bit number within the word */
_mali_internal_set_bit( nr, addr );
}
/** @brief Test a bit in a sequence of 32-bit words
* @param nr bit number to test, starting from the (Little-endian) least
* significant bit
* @param addr starting point for counting.
* @return zero if bit was clear, non-zero if set. Do not rely on the return
* value being related to the actual word under test.
*/
MALI_STATIC_INLINE u32 _mali_osk_test_bit( u32 nr, u32 *addr )
{
addr += nr >> 5; /* find the correct word */
nr = nr & ((1 << 5)-1); /* The bit number within the word */
return _mali_internal_test_bit( nr, *addr );
}
/* Return maxbit if not found */
/** @brief Find the first zero bit in a sequence of 32-bit words
* @param addr starting point for search.
* @param maxbit the maximum number of bits to search
* @return the number of the first zero bit found, or maxbit if none were found
* in the specified range.
*/
MALI_STATIC_INLINE u32 _mali_osk_find_first_zero_bit( const u32 *addr, u32 maxbit )
{
u32 total;
for ( total = 0; total < maxbit; total += 32, ++addr )
{
int result;
result = _mali_internal_find_first_zero_bit( *addr );
/* non-negative signifies the bit was found */
if ( result >= 0 )
{
total += (u32)result;
break;
}
}
/* Now check if we reached maxbit or above */
if ( total >= maxbit )
{
total = maxbit;
}
return total; /* either the found bit nr, or maxbit if not found */
}
/** @} */ /* end group _mali_osk_bitops */
#ifdef __cplusplus
}
#endif
#endif /* __MALI_OSK_BITOPS_H__ */
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