diff options
author | chai <chaifix@163.com> | 2019-08-14 22:50:43 +0800 |
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committer | chai <chaifix@163.com> | 2019-08-14 22:50:43 +0800 |
commit | 15740faf9fe9fe4be08965098bbf2947e096aeeb (patch) | |
tree | a730ec236656cc8cab5b13f088adfaed6bb218fb /Runtime/Allocator/tlsf/tlsfbits.h |
Diffstat (limited to 'Runtime/Allocator/tlsf/tlsfbits.h')
-rw-r--r-- | Runtime/Allocator/tlsf/tlsfbits.h | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/Runtime/Allocator/tlsf/tlsfbits.h b/Runtime/Allocator/tlsf/tlsfbits.h new file mode 100644 index 0000000..a41a959 --- /dev/null +++ b/Runtime/Allocator/tlsf/tlsfbits.h @@ -0,0 +1,184 @@ +#ifndef INCLUDED_tlsfbits +#define INCLUDED_tlsfbits + +#if defined(__cplusplus) +#define tlsf_decl inline +#else +#define tlsf_decl static +#endif + +/* +** Architecture-specific bit manipulation routines. +** +** TLSF achieves O(1) cost for malloc and free operations by limiting +** the search for a free block to a free list of guaranteed size +** adequate to fulfill the request, combined with efficient free list +** queries using bitmasks and architecture-specific bit-manipulation +** routines. +** +** Most modern processors provide instructions to count leading zeroes +** in a word, find the lowest and highest set bit, etc. These +** specific implementations will be used when available, falling back +** to a reasonably efficient generic implementation. +** +** NOTE: TLSF spec relies on ffs/fls returning value 0..31. +** ffs/fls return 1-32 by default, returning 0 for error. +*/ + +/* +** Detect whether or not we are building for a 32- or 64-bit (LP/LLP) +** architecture. There is no reliable portable method at compile-time. +*/ + +// native client uses ILP32, even when building for x86_64, so make sure +// that pointer sizes are treated as 32 bits. +#if !defined(__native_client__) +#if defined (__alpha__) || defined (__ia64__) || defined (__x86_64__) \ + || defined (_WIN64) || defined (__LP64__) || defined (__LLP64__) +#define TLSF_64BIT +#endif +#endif +/* +** gcc 3.4 and above have builtin support, specialized for architecture. +** Some compilers masquerade as gcc; patchlevel test filters them out. +*/ +#if defined (__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) \ + && defined (__GNUC_PATCHLEVEL__) + +tlsf_decl int tlsf_ffs(unsigned int word) +{ + return __builtin_ffs(word) - 1; +} + +tlsf_decl int tlsf_fls(unsigned int word) +{ + const int bit = word ? 32 - __builtin_clz(word) : 0; + return bit - 1; +} + +#elif defined (_MSC_VER) && defined (_M_IX86) && (_MSC_VER >= 1400) +/* Microsoft Visual C++ 2005 support on x86 architectures. */ + +#include <intrin.h> + +#pragma intrinsic(_BitScanReverse) +#pragma intrinsic(_BitScanForward) + +tlsf_decl int tlsf_fls(unsigned int word) +{ + unsigned long index; + return _BitScanReverse(&index, word) ? index : -1; +} + +tlsf_decl int tlsf_ffs(unsigned int word) +{ + unsigned long index; + return _BitScanForward(&index, word) ? index : -1; +} + +#elif defined (_MSC_VER) && defined (_M_PPC) +/* Microsoft Visual C++ support on PowerPC architectures. */ + +#include <ppcintrinsics.h> + +tlsf_decl int tlsf_fls(unsigned int word) +{ + const int bit = 32 - _CountLeadingZeros(word); + return bit - 1; +} + +tlsf_decl int tlsf_ffs(unsigned int word) +{ + const unsigned int reverse = word & (~word + 1); + const int bit = 32 - _CountLeadingZeros(reverse); + return bit - 1; +} + +#elif defined (__ARMCC_VERSION) +/* RealView Compilation Tools for ARM */ + +tlsf_decl int tlsf_ffs(unsigned int word) +{ + const unsigned int reverse = word & (~word + 1); + const int bit = 32 - __clz(reverse); + return bit - 1; +} + +tlsf_decl int tlsf_fls(unsigned int word) +{ + const int bit = word ? 32 - __clz(word) : 0; + return bit - 1; +} + +#elif defined (__ghs__) +/* Green Hills support for PowerPC */ + +#include <ppc_ghs.h> + +tlsf_decl int tlsf_ffs(unsigned int word) +{ + const unsigned int reverse = word & (~word + 1); + const int bit = 32 - __CLZ32(reverse); + return bit - 1; +} + +tlsf_decl int tlsf_fls(unsigned int word) +{ + const int bit = word ? 32 - __CLZ32(word) : 0; + return bit - 1; +} + +#else +/* Fall back to generic implementation. */ + +tlsf_decl int tlsf_fls_generic(unsigned int word) +{ + int bit = 32; + + if (!word) bit -= 1; + if (!(word & 0xffff0000)) { word <<= 16; bit -= 16; } + if (!(word & 0xff000000)) { word <<= 8; bit -= 8; } + if (!(word & 0xf0000000)) { word <<= 4; bit -= 4; } + if (!(word & 0xc0000000)) { word <<= 2; bit -= 2; } + if (!(word & 0x80000000)) { word <<= 1; bit -= 1; } + + return bit; +} + +/* Implement ffs in terms of fls. */ +tlsf_decl int tlsf_ffs(unsigned int word) +{ + return tlsf_fls_generic(word & (~word + 1)) - 1; +} + +tlsf_decl int tlsf_fls(unsigned int word) +{ + return tlsf_fls_generic(word) - 1; +} + +#endif + +/* Possibly 64-bit version of tlsf_fls. */ +#if defined (TLSF_64BIT) +tlsf_decl int tlsf_fls_sizet(size_t size) +{ + int high = (int)(size >> 32); + int bits = 0; + if (high) + { + bits = 32 + tlsf_fls(high); + } + else + { + bits = tlsf_fls((int)size & 0xffffffff); + + } + return bits; +} +#else +#define tlsf_fls_sizet tlsf_fls +#endif + +#undef tlsf_decl + +#endif |