* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
*/
-FILE_LICENCE ( GPL2_OR_LATER );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** @file
*
*
*/
-#define __HAVE_ARCH_MEMCPY
-
extern void * __memcpy ( void *dest, const void *src, size_t len );
extern void * __memcpy_reverse ( void *dest, const void *src, size_t len );
}
}
-#define __HAVE_ARCH_MEMMOVE
-
extern void * __memmove ( void *dest, const void *src, size_t len );
/**
}
}
-#define __HAVE_ARCH_MEMSET
-
/**
* Fill memory region
*
* @v len Length
* @ret dest Destination address
*/
-static inline void * memset ( void *dest, int fill, size_t len ) {
+static inline __attribute__ (( always_inline )) void *
+__memset ( void *dest, int fill, size_t len ) {
void *discard_D;
size_t discard_c;
return dest;
}
-#define __HAVE_ARCH_MEMSWAP
+/**
+ * Fill memory region with zero (where length is a compile-time constant)
+ *
+ * @v dest Destination address
+ * @v len Length
+ * @ret dest Destination address
+ */
+static inline __attribute__ (( always_inline )) void *
+__constant_memset_zero ( void *dest, size_t len ) {
+ union {
+ uint32_t u32[2];
+ uint16_t u16[4];
+ uint8_t u8[8];
+ } __attribute__ (( __may_alias__ )) *dest_u = dest;
+ void *edi;
+ uint32_t eax;
+
+ switch ( len ) {
+ case 0 : /* 0 bytes */
+ return dest;
+
+ /* Single-register moves. Almost certainly better than a
+ * string operation. We can avoid clobbering any registers,
+ * we can reuse a zero that happens to already be in a
+ * register, and we can optimise away the code entirely if the
+ * memset() is used to clear a region which then gets
+ * immediately overwritten.
+ */
+ case 1 : /* 3 bytes */
+ dest_u->u8[0] = 0;
+ return dest;
+ case 2: /* 5 bytes */
+ dest_u->u16[0] = 0;
+ return dest;
+ case 4: /* 6 bytes */
+ dest_u->u32[0] = 0;
+ return dest;
+
+ /* Double-register moves. Very probably better than a string
+ * operation.
+ */
+ case 3 : /* 9 bytes */
+ dest_u->u16[0] = 0;
+ dest_u->u8[2] = 0;
+ return dest;
+ case 5 : /* 10 bytes */
+ dest_u->u32[0] = 0;
+ dest_u->u8[4] = 0;
+ return dest;
+ case 6 : /* 12 bytes */
+ dest_u->u32[0] = 0;
+ dest_u->u16[2] = 0;
+ return dest;
+ case 8 : /* 13 bytes */
+ dest_u->u32[0] = 0;
+ dest_u->u32[1] = 0;
+ return dest;
+ }
+
+ /* As with memcpy(), we can potentially save space by using
+ * multiple single-byte "stos" instructions instead of loading
+ * up ecx and using "rep stosb".
+ *
+ * "load ecx, rep movsb" is 7 bytes, plus an average of 1 byte
+ * to allow for saving/restoring ecx 50% of the time.
+ *
+ * "stosl" and "stosb" are 1 byte each, "stosw" is two bytes.
+ *
+ * The calculations are therefore the same as for memcpy(),
+ * giving a cutoff point of around 26 bytes.
+ */
-extern void * memswap ( void *dest, void *src, size_t len );
+ edi = dest;
+ eax = 0;
+
+ if ( len >= 26 )
+ return __memset ( dest, 0, len );
-#define __HAVE_ARCH_STRNCMP
+ if ( len >= 6*4 )
+ __asm__ __volatile__ ( "stosl" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( len >= 5*4 )
+ __asm__ __volatile__ ( "stosl" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( len >= 4*4 )
+ __asm__ __volatile__ ( "stosl" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( len >= 3*4 )
+ __asm__ __volatile__ ( "stosl" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( len >= 2*4 )
+ __asm__ __volatile__ ( "stosl" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( len >= 1*4 )
+ __asm__ __volatile__ ( "stosl" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( ( len % 4 ) >= 2 )
+ __asm__ __volatile__ ( "stosw" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
+ if ( ( len % 2 ) >= 1 )
+ __asm__ __volatile__ ( "stosb" : "=&D" ( edi ), "=&a" ( eax )
+ : "0" ( edi ), "1" ( eax ) : "memory" );
-extern int strncmp ( const char *str1, const char *str2, size_t len );
+ return dest;
+}
-#define __HAVE_ARCH_STRLEN
+/**
+ * Fill memory region
+ *
+ * @v dest Destination address
+ * @v fill Fill pattern
+ * @v len Length
+ * @ret dest Destination address
+ */
+static inline __attribute__ (( always_inline )) void *
+memset ( void *dest, int fill, size_t len ) {
-extern size_t strlen ( const char *string );
+ if ( __builtin_constant_p ( fill ) && ( fill == 0 ) &&
+ __builtin_constant_p ( len ) ) {
+ return __constant_memset_zero ( dest, len );
+ } else {
+ return __memset ( dest, fill, len );
+ }
+}
#endif /* X86_BITS_STRING_H */
Code Review / kvmfornfv.git / blobdiff