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Added __constant_memcpy() based on version in Linux's string.h.
Added memswap().
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@ -3,6 +3,9 @@
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/*
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* Taken from Linux /usr/include/asm/string.h
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* All except memcpy, memmove, memset and memcmp removed.
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*
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* Non-standard memswap() function added because it saves quite a bit
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* of code (mbrown@fensystems.co.uk).
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*/
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/*
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@ -19,19 +22,122 @@
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*/
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#define __HAVE_ARCH_MEMCPY
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static inline void * memcpy(void *dest, const void *src, size_t n)
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{
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int d0, d1, d2;
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__asm__ __volatile__ (
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"cld\n\t"
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"rep\n\t"
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"movsb"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2)
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:"0" (n), "1" (src), "2" (dest)
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: "memory");
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return dest;
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static inline __attribute__ (( always_inline )) void *
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__memcpy ( void *dest, const void *src, size_t len ) {
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int d0, d1, d2;
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__asm__ __volatile__ ( "rep ; movsb"
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: "=&c" ( d0 ), "=&S" ( d1 ), "=&D" ( d2 )
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: "0" ( len ), "1" ( src ), "2" ( dest )
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: "memory" );
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return dest;
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}
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static inline __attribute__ (( always_inline )) void *
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__constant_memcpy ( void *dest, const void *src, size_t len ) {
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const void *esi;
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void *edi;
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switch ( len ) {
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case 0 : /* 0 bytes */
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return dest;
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/*
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* Single-register moves; these are always better than a
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* string operation. We can clobber an arbitrary two
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* registers (data, source, dest can re-use source register)
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* instead of being restricted to esi and edi. There's also a
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* much greater potential for optimising with nearby code.
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*
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*/
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case 1 : /* 4 bytes */
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* ( uint8_t * ) ( dest + 0 ) = * ( uint8_t * ) ( src + 0 );
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return dest;
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case 2 : /* 6 bytes */
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* ( uint16_t * ) ( dest + 0 ) = * ( uint16_t * ) ( src + 0 );
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return dest;
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case 4 : /* 4 bytes */
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* ( uint32_t * ) ( dest + 0 ) = * ( uint32_t * ) ( src + 0 );
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return dest;
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/*
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* Double-register moves; these are probably still a win.
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*
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*/
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case 3 : /* 12 bytes */
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* ( uint16_t * ) ( dest + 0 ) = * ( uint16_t * ) ( src + 0 );
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* ( uint8_t * ) ( dest + 2 ) = * ( uint8_t * ) ( src + 2 );
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return dest;
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case 5 : /* 10 bytes */
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* ( uint32_t * ) ( dest + 0 ) = * ( uint32_t * ) ( src + 0 );
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* ( uint8_t * ) ( dest + 4 ) = * ( uint8_t * ) ( src + 4 );
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return dest;
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case 6 : /* 12 bytes */
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* ( uint32_t * ) ( dest + 0 ) = * ( uint32_t * ) ( src + 0 );
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* ( uint16_t * ) ( dest + 4 ) = * ( uint16_t * ) ( src + 4 );
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return dest;
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case 8 : /* 10 bytes */
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* ( uint32_t * ) ( dest + 0 ) = * ( uint32_t * ) ( src + 0 );
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* ( uint32_t * ) ( dest + 4 ) = * ( uint32_t * ) ( src + 4 );
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return dest;
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}
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/* Even if we have to load up esi and edi ready for a string
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* operation, we can sometimes save space by using multiple
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* single-byte "movs" operations instead of loading up ecx and
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* using "rep movsb".
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*
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* "load ecx, rep movsb" is 7 bytes, plus an average of 1 byte
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* to allow for saving/restoring ecx 50% of the time.
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*
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* "movsl" and "movsb" are 1 byte each, "movsw" is two bytes.
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* (In 16-bit mode, "movsl" is 2 bytes and "movsw" is 1 byte,
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* but "movsl" moves twice as much data, so it balances out).
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*
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* The cutoff point therefore occurs around 26 bytes; the byte
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* requirements for each method are:
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*
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* len 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
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* #bytes (ecx) 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
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* #bytes (no ecx) 4 5 6 7 5 6 7 8 6 7 8 9 7 8 9 10
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*/
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esi = src;
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edi = dest;
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if ( len >= 26 )
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return __memcpy ( dest, src, len );
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if ( len >= 6*4 )
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__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( len >= 5*4 )
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__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( len >= 4*4 )
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__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( len >= 3*4 )
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__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( len >= 2*4 )
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__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( len >= 1*4 )
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__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( ( len % 4 ) >= 2 )
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__asm__ __volatile__ ( "movsw" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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if ( ( len % 2 ) >= 1 )
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__asm__ __volatile__ ( "movsb" : "=&D" ( edi ), "=&S" ( esi )
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: "0" ( edi ), "1" ( esi ) : "memory" );
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return dest;
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}
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#define memcpy( dest, src, len ) \
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( __builtin_constant_p ( (len) ) ? \
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__constant_memcpy ( (dest), (src), (len) ) : \
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__memcpy ( (dest), (src), (len) ) )
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#define __HAVE_ARCH_MEMMOVE
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static inline void * memmove(void * dest,const void * src, size_t n)
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{
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@ -59,7 +165,7 @@ return dest;
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}
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#define __HAVE_ARCH_MEMSET
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static inline void *memset(void *s, int c,size_t count)
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static inline void * memset(void *s, int c,size_t count)
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{
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int d0, d1;
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__asm__ __volatile__(
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@ -72,6 +178,23 @@ __asm__ __volatile__(
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return s;
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}
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#define __HAVE_ARCH_MEMSWAP
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static inline void * memswap(void *dest, void *src, size_t n)
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{
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int d0, d1, d2, d3;
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__asm__ __volatile__(
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"\n1:\t"
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"movb (%%edi),%%al\n\t"
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"xchgb (%%esi),%%al\n\t"
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"incl %%esi\n\t"
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"stosb\n\t"
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"loop 1b"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2), "=&a" (d3)
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: "0" (n), "1" (src), "2" (dest)
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: "memory" );
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return dest;
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}
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#define __HAVE_ARCH_STRNCMP
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static inline int strncmp(const char * cs,const char * ct,size_t count)
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{
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