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Experimental optimization of the bit copy algorithm with special cases

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This commit is contained in:
Pavel Kirienko
2015-01-11 04:35:03 +03:00
parent 21c07b90a5
commit 20439bb397
2 changed files with 181 additions and 5 deletions
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libuavcan/include/uavcan/marshal/bit_stream.hpp
+28
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@@ -12,6 +12,8 @@
namespace uavcan
{
#if UAVCAN_TINY
/**
* This function implements fast copy of unaligned bit arrays. It isn't part of the library API, so it is not exported.
* @param src_org Source array
@@ -22,6 +24,16 @@ namespace uavcan
*/
void bitarrayCopy(const unsigned char* src_org, unsigned src_offset, unsigned src_len,
unsigned char* dst_org, unsigned dst_offset);
#else
/**
* Special cases of @ref bitarrayCopy() - either source or destination must be aligned.
* These functions aren't part of the library API, so they are not exported.
*/
void bitarrayCopyAlignedToUnaligned(const unsigned char* src_org, unsigned src_len,
unsigned char* dst_org, unsigned dst_offset);
void bitarrayCopyUnalignedToAligned(const unsigned char* src_org, unsigned src_offset, unsigned src_len,
unsigned char* dst_org);
#endif
/**
* This class treats a chunk of memory as an array of bits.
@@ -37,6 +49,7 @@ class UAVCAN_EXPORT BitStream
static inline unsigned bitlenToBytelen(unsigned bits) { return (bits + 7) / 8; }
#if UAVCAN_TINY
static inline void copyBitArrayAlignedToUnaligned(const uint8_t* src_org, unsigned src_len,
uint8_t* dst_org, unsigned dst_offset)
{
@@ -50,6 +63,21 @@ class UAVCAN_EXPORT BitStream
bitarrayCopy(reinterpret_cast<const unsigned char*>(src_org), src_offset, src_len,
reinterpret_cast<unsigned char*>(dst_org), 0);
}
#else
static inline void copyBitArrayAlignedToUnaligned(const uint8_t* src_org, unsigned src_len,
uint8_t* dst_org, unsigned dst_offset)
{
bitarrayCopyAlignedToUnaligned(reinterpret_cast<const unsigned char*>(src_org), src_len,
reinterpret_cast<unsigned char*>(dst_org), dst_offset);
}
static inline void copyBitArrayUnalignedToAligned(const uint8_t* src_org, unsigned src_offset, unsigned src_len,
uint8_t* dst_org)
{
bitarrayCopyUnalignedToAligned(reinterpret_cast<const unsigned char*>(src_org), src_offset, src_len,
reinterpret_cast<unsigned char*>(dst_org));
}
#endif
public:
static const unsigned MaxBitsPerRW = MaxBytesPerRW * 8;