#ifndef ETHERBOOT_BITS_STRING_H
#define ETHERBOOT_BITS_STRING_H
/*
* Taken from Linux /usr/include/asm/string.h
* All except memcpy, memmove, memset and memcmp removed.
*
* Non-standard memswap() function added because it saves quite a bit
* of code (mbrown@fensystems.co.uk).
*/
/*
* This string-include defines all string functions as inline
* functions. Use gcc. It also assumes ds=es=data space, this should be
* normal. Most of the string-functions are rather heavily hand-optimized,
* see especially strtok,strstr,str[c]spn. They should work, but are not
* very easy to understand. Everything is done entirely within the register
* set, making the functions fast and clean. String instructions have been
* used through-out, making for "slightly" unclear code :-)
*
* NO Copyright (C) 1991, 1992 Linus Torvalds,
* consider these trivial functions to be PD.
*/
FILE_LICENCE ( PUBLIC_DOMAIN );
#define __HAVE_ARCH_MEMCPY
extern void * __memcpy ( void *dest, const void *src, size_t len );
#if 0
static inline __attribute__ (( always_inline )) void *
__memcpy ( void *dest, const void *src, size_t len ) {
int d0, d1, d2;
__asm__ __volatile__ ( "rep ; movsb"
: "=&c" ( d0 ), "=&S" ( d1 ), "=&D" ( d2 )
: "0" ( len ), "1" ( src ), "2" ( dest )
: "memory" );
return dest;
}
#endif
static inline __attribute__ (( always_inline )) void *
__constant_memcpy ( void *dest, const void *src, size_t len ) {
union {
uint32_t u32[2];
uint16_t u16[4];
uint8_t u8[8];
} __attribute__ (( __may_alias__ )) *dest_u = dest;
const union {
uint32_t u32[2];
uint16_t u16[4];
uint8_t u8[8];
} __attribute__ (( __may_alias__ )) *src_u = src;
const void *esi;
void *edi;
switch ( len ) {
case 0 : /* 0 bytes */
return dest;
/*
* Single-register moves; these are always better than a
* string operation. We can clobber an arbitrary two
* registers (data, source, dest can re-use source register)
* instead of being restricted to esi and edi. There's also a
* much greater potential for optimising with nearby code.
*
*/
case 1 : /* 4 bytes */
dest_u->u8[0] = src_u->u8[0];
return dest;
case 2 : /* 6 bytes */
dest_u->u16[0] = src_u->u16[0];
return dest;
case 4 : /* 4 bytes */
dest_u->u32[0] = src_u->u32[0];
return dest;
/*
* Double-register moves; these are probably still a win.
*
*/
case 3 : /* 12 bytes */
dest_u->u16[0] = src_u->u16[0];
dest_u->u8[2] = src_u->u8[2];
return dest;
case 5 : /* 10 bytes */
dest_u->u32[0] = src_u->u32[0];
dest_u->u8[4] = src_u->u8[4];
return dest;
case 6 : /* 12 bytes */
dest_u->u32[0] = src_u->u32[0];
dest_u->u16[2] = src_u->u16[2];
return dest;
case 8 : /* 10 bytes */
dest_u->u32[0] = src_u->u32[0];
dest_u->u32[1] = src_u->u32[1];
return dest;
}
/* Even if we have to load up esi and edi ready for a string
* operation, we can sometimes save space by using multiple
* single-byte "movs" operations instead of loading up ecx and
* using "rep movsb".
*
* "load ecx, rep movsb" is 7 bytes, plus an average of 1 byte
* to allow for saving/restoring ecx 50% of the time.
*
* "movsl" and "movsb" are 1 byte each, "movsw" is two bytes.
* (In 16-bit mode, "movsl" is 2 bytes and "movsw" is 1 byte,
* but "movsl" moves twice as much data, so it balances out).
*
* The cutoff point therefore occurs around 26 bytes; the byte
* requirements for each method are:
*
* len 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
* #bytes (ecx) 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
* #bytes (no ecx) 4 5 6 7 5 6 7 8 6 7 8 9 7 8 9 10
*/
esi = src;
edi = dest;
if ( len >= 26 )
return __memcpy ( dest, src, len );
if ( len >= 6*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 5*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 4*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 3*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 2*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 1*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( ( len % 4 ) >= 2 )
__asm__ __volatile__ ( "movsw" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( ( len % 2 ) >= 1 )
__asm__ __volatile__ ( "movsb" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
return dest;
}
#define memcpy( dest, src, len ) \
( __builtin_constant_p ( (len) ) ? \
__constant_memcpy ( (dest), (src), (len) ) : \
__memcpy ( (dest), (src), (len) ) )
#define __HAVE_ARCH_MEMMOVE
static inline void * memmove(void * dest,const void * src, size_t n)
{
int d0, d1, d2;
if (dest<src)
__asm__ __volatile__(
"cld\n\t"
"rep\n\t"
"movsb"
: "=&c" (d0), "=&S" (d1), "=&D" (d2)
:"0" (n),"1" (src),"2" (dest)
: "memory");
else
__asm__ __volatile__(
"std\n\t"
"rep\n\t"
"movsb\n\t"
"cld"
: "=&c" (d0), "=&S" (d1), "=&D" (d2)
:"0" (n),
"1" (n-1+(const char *)src),
"2" (n-1+(char *)dest)
:"memory");
return dest;
}
#define __HAVE_ARCH_MEMSET
static inline void * memset(void *s, int c,size_t count)
{
int d0, d1;
__asm__ __volatile__(
"cld\n\t"
"rep\n\t"
"stosb"
: "=&c" (d0), "=&D" (d1)
:"a" (c),"1" (s),"0" (count)
:"memory");
return s;
}
#define __HAVE_ARCH_MEMSWAP
static inline void * memswap(void *dest, void *src, size_t n)
{
int d0, d1, d2, d3;
__asm__ __volatile__(
"\n1:\t"
"movb (%%edi),%%al\n\t"
"xchgb (%%esi),%%al\n\t"
"incl %%esi\n\t"
"stosb\n\t"
"loop 1b"
: "=&c" (d0), "=&S" (d1), "=&D" (d2), "=&a" (d3)
: "0" (n), "1" (src), "2" (dest)
: "memory" );
return dest;
}
#define __HAVE_ARCH_STRNCMP
static inline int strncmp(const char * cs,const char * ct,size_t count)
{
register int __res;
int d0, d1, d2;
__asm__ __volatile__(
"1:\tdecl %3\n\t"
"js 2f\n\t"
"lodsb\n\t"
"scasb\n\t"
"jne 3f\n\t"
"testb %%al,%%al\n\t"
"jne 1b\n"
"2:\txorl %%eax,%%eax\n\t"
"jmp 4f\n"
"3:\tsbbl %%eax,%%eax\n\t"
"orb $1,%%al\n"
"4:"
:"=a" (__res), "=&S" (d0), "=&D" (d1), "=&c" (d2)
:"1" (cs),"2" (ct),"3" (count));
return __res;
}
#define __HAVE_ARCH_STRLEN
static inline size_t strlen(const char * s)
{
int d0;
register int __res;
__asm__ __volatile__(
"repne\n\t"
"scasb\n\t"
"notl %0\n\t"
"decl %0"
:"=c" (__res), "=&D" (d0) :"1" (s),"a" (0), "0" (0xffffffff));
return __res;
}
#endif /* ETHERBOOT_BITS_STRING_H */
