56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
#ifndef INCLUDED_tlsfbits
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#define INCLUDED_tlsfbits
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#include <linux/bitops.h>
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/*
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** Architecture-specific bit manipulation routines.
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**
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** TLSF achieves O(1) cost for malloc and free operations by limiting
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** the search for a free block to a free list of guaranteed size
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** adequate to fulfill the request, combined with efficient free list
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** queries using bitmasks and architecture-specific bit-manipulation
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** routines.
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**
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** Most modern processors provide instructions to count leading zeroes
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** in a word, find the lowest and highest set bit, etc. These
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** specific implementations will be used when available, falling back
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** to a reasonably efficient generic implementation.
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**
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** NOTE: TLSF spec relies on ffs/fls returning value 0..31.
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** ffs/fls return 1-32 by default, returning 0 for error.
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*/
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static int tlsf_ffs(unsigned int word)
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{
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return ffs(word) - 1;
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}
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static int tlsf_fls(unsigned int word)
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{
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return fls(word) - 1;
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}
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/* Possibly 64-bit version of tlsf_fls. */
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#if defined (TLSF_64BIT)
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tlsf_decl int tlsf_fls_sizet(size_t size)
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{
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int high = (int)(size >> 32);
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int bits = 0;
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if (high)
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{
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bits = 32 + tlsf_fls(high);
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}
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else
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{
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bits = tlsf_fls((int)size & 0xffffffff);
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}
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return bits;
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}
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#else
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#define tlsf_fls_sizet tlsf_fls
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#endif
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#endif
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