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/*
* Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball
*/
#if !defined _STRING_H
#error "Never use <libc-string_i386.h> directly; include <string.h> instead"
#endif
#ifndef _LIBC_STRING_i386_H
#define _LIBC_STRING_i386_H 1
static __always_inline
void *inlined_memset_const_c_count4(void *s, unsigned eax, unsigned count)
{
int ecx, edi;
if (count == 0)
return s;
/* Very small (2 stores or less) are best done with direct
* mov <const>,<mem> instructions (they do not clobber registers) */
if (count == 1) {
*(char *)(s + 0) = eax;
return s;
}
/* You wonder why & 0xff is needed? Try memset(p, '\xff', size).
* If char is signed, '\xff' == -1! */
eax = (eax & 0xff) * 0x01010101; /* done at compile time */
if (count == 2) {
*(short *)(s + 0) = eax;
return s;
}
if (count == 3) {
*(short *)(s + 0) = eax;
*(char *) (s + 2) = eax;
return s;
}
if (count == 1*4 + 0) {
*(int *)(s + 0) = eax;
return s;
}
if (count == 1*4 + 1) {
*(int *) (s + 0) = eax;
*(char *)(s + 4) = eax;
return s;
}
if (count == 1*4 + 2) {
*(int *) (s + 0) = eax;
*(short *)(s + 4) = eax;
return s;
}
/* Small string stores: don't clobber ecx
* (clobbers only eax and edi) */
#define small_store(arg) { \
__asm__ __volatile__( \
arg \
: "=&D" (edi) \
: "a" (eax), "0" (s) \
: "memory" \
); \
return s; \
}
if (count == 1*4 + 3) small_store("stosl; stosw; stosb");
if (count == 2*4 + 0) {
((int *)s)[0] = eax;
((int *)s)[1] = eax;
return s;
}
if (count == 2*4 + 1) small_store("stosl; stosl; stosb");
if (count == 2*4 + 2) small_store("stosl; stosl; stosw");
if (count == 2*4 + 3) small_store("stosl; stosl; stosw; stosb");
if (count == 3*4 + 0) small_store("stosl; stosl; stosl");
if (count == 3*4 + 1) small_store("stosl; stosl; stosl; stosb");
if (count == 3*4 + 2) small_store("stosl; stosl; stosl; stosw");
if (count == 3*4 + 3) small_store("stosl; stosl; stosl; stosw; stosb");
if (count == 4*4 + 0) small_store("stosl; stosl; stosl; stosl");
if (count == 4*4 + 1) small_store("stosl; stosl; stosl; stosl; stosb");
/* going over 7 bytes is suboptimal */
/* stosw is 2-byte insn, so this one takes 6 bytes: */
if (count == 4*4 + 2) small_store("stosl; stosl; stosl; stosl; stosw");
/* 7 bytes */
if (count == 4*4 + 3) small_store("stosl; stosl; stosl; stosl; stosw; stosb");
/* 5 bytes */
if (count == 5*4 + 0) small_store("stosl; stosl; stosl; stosl; stosl");
/* 6 bytes */
if (count == 5*4 + 1) small_store("stosl; stosl; stosl; stosl; stosl; stosb");
/* 7 bytes */
if (count == 5*4 + 2) small_store("stosl; stosl; stosl; stosl; stosl; stosw");
/* 8 bytes, but oh well... */
if (count == 5*4 + 3) small_store("stosl; stosl; stosl; stosl; stosl; stosw; stosb");
/* 6 bytes */
if (count == 6*4 + 0) small_store("stosl; stosl; stosl; stosl; stosl; stosl");
/* the rest would be 7+ bytes and is handled below instead */
#undef small_store
/* Not small, but multiple-of-4 store.
* "mov <const>,%ecx; rep; stosl" sequence is 7 bytes */
__asm__ __volatile__(
" rep; stosl\n"
: "=&c" (ecx), "=&D" (edi)
: "a" (eax), "0" (count / 4), "1" (s)
: "memory"
);
return s;
}
#if 1 /* -51 bytes on shared i386 build with gcc 4.3.0 */
#define memset(s, c, count) ( \
( !(__builtin_constant_p(c) && __builtin_constant_p(count)) \
|| ((count) > (6*4 + 0) && ((count) % 4) != 0) \
) \
? memset((s), (c), (count)) \
: inlined_memset_const_c_count4((s), (c), (count)) \
)
#endif
static __always_inline
void *inlined_mempcpy_const_count4(void *d, const void *s, unsigned count)
{
int ecx;
char *esi, *edi;
if (count == 0)
return d;
if (count == 1) {
*(char *)d = *(char *)s;
return d + 1;
}
if (count == 2) {
*(short *)d = *(short *)s;
return d + 2;
}
/* Small string moves: don't clobber ecx
* (clobbers only esi and edi) */
#define small_move(arg) { \
__asm__ __volatile__( \
arg \
: "=&S" (esi), "=&D" (edi) \
: "0" (s), "1" (d) \
: "memory" \
); \
return edi; \
}
if (count == 3) small_move("movsw; movsb");
if (count == 1*4 + 0) {
*(int *)d = *(int *)s;
return d + 4;
}
if (count == 1*4 + 1) small_move("movsl; movsb");
if (count == 1*4 + 2) small_move("movsl; movsw");
if (count == 1*4 + 3) small_move("movsl; movsw; movsb");
if (count == 2*4 + 0) small_move("movsl; movsl");
if (count == 2*4 + 1) small_move("movsl; movsl; movsb");
if (count == 2*4 + 2) small_move("movsl; movsl; movsw");
if (count == 2*4 + 3) small_move("movsl; movsl; movsw; movsb");
if (count == 3*4 + 0) small_move("movsl; movsl; movsl");
if (count == 3*4 + 1) small_move("movsl; movsl; movsl; movsb");
if (count == 3*4 + 2) small_move("movsl; movsl; movsl; movsw");
if (count == 3*4 + 3) small_move("movsl; movsl; movsl; movsw; movsb");
if (count == 4*4 + 0) small_move("movsl; movsl; movsl; movsl");
if (count == 4*4 + 1) small_move("movsl; movsl; movsl; movsl; movsb");
/* going over 7 bytes is suboptimal */
/* movsw is 2-byte insn, so this one takes 6 bytes: */
if (count == 4*4 + 2) small_move("movsl; movsl; movsl; movsl; movsw");
/* 7 bytes */
if (count == 4*4 + 3) small_move("movsl; movsl; movsl; movsl; movsw; movsb");
/* 5 bytes */
if (count == 5*4 + 0) small_move("movsl; movsl; movsl; movsl; movsl");
/* 6 bytes */
if (count == 5*4 + 1) small_move("movsl; movsl; movsl; movsl; movsl; movsb");
/* 7 bytes */
if (count == 5*4 + 2) small_move("movsl; movsl; movsl; movsl; movsl; movsw");
/* 8 bytes, but oh well... */
if (count == 5*4 + 3) small_move("movsl; movsl; movsl; movsl; movsl; movsw; movsb");
/* 6 bytes */
if (count == 6*4 + 0) small_move("movsl; movsl; movsl; movsl; movsl; movsl");
/* the rest would be 7+ bytes and is handled below instead */
#undef small_move
/* Not small, but multiple-of-4 move.
* "mov <const>,%ecx; rep; movsl" sequence is 7 bytes */
__asm__ __volatile__(
" rep; movsl\n"
: "=&c" (ecx), "=&S" (esi), "=&D" (edi)
: "0" (count / 4), "1" (s), "2" (d)
: "memory"
);
return edi;
}
static __always_inline
void *inlined_memcpy_const_count4(void *d, const void *s, unsigned count)
{
inlined_mempcpy_const_count4(d, s, count);
return d;
}
#if 1 /* +34 bytes on shared i386 build with gcc 4.3.0 */
#define mempcpy(d, s, count) ( \
( !(__builtin_constant_p(count)) \
|| ((count) > (6*4 + 0) && ((count) % 4) != 0) \
) \
? mempcpy((d), (s), (count)) \
: inlined_mempcpy_const_count4((d), (s), (count)) \
)
#define memcpy(d, s, count) ( \
( !(__builtin_constant_p(count)) \
|| ((count) > (6*4 + 0) && ((count) % 4) != 0) \
) \
? memcpy((d), (s), (count)) \
: inlined_memcpy_const_count4((d), (s), (count)) \
)
#endif
static __always_inline
size_t inlined_strlen(const char *s)
{
int edi;
int ecx;
__asm__ __volatile__(
" repne; scasb\n"
/* " notl %0\n" */
/* " decl %0\n" */
: "=c" (ecx), "=&D" (edi)
: "1" (s), "a" (0), "0" (0xffffffffu)
/* : no clobbers */
);
return -ecx - 1;
}
#if 0 /* +1108 bytes on shared i386 build with gcc 4.3.0 */
#define strlen(s) inlined_strlen(s)
#endif
static __always_inline
char *inlined_stpcpy(char *dest, const char *src)
{
char *esi, *edi;
int eax;
__asm__ __volatile__(
"1: lodsb\n"
" stosb\n"
" testb %%al, %%al\n"
" jnz 1b\n"
: "=&S" (esi), "=&D" (edi), "=&a" (eax)
: "0" (src), "1" (dest)
: "memory"
);
return edi - 1;
}
static __always_inline
char *inlined_strcpy(char *dest, const char *src)
{
inlined_stpcpy(dest, src);
return dest;
}
#if 0 /* +562 bytes on shared i386 build with gcc 4.3.0 */
#define stpcpy(dest, src) inlined_stpcpy(dest, src)
#define strcpy(dest, src) inlined_strcpy(dest, src)
#endif
static __always_inline
void *inlined_memchr(const void *s, int c, size_t count)
{
void *edi;
int ecx;
/* Unfortunately, c gets loaded to %eax (wide insn), not %al */
__asm__ __volatile__(
" jecxz 1f\n"
" repne; scasb\n"
" leal -1(%%edi), %%edi\n"
" je 2f\n"
"1:\n"
" xorl %%edi, %%edi\n"
"2:\n"
: "=&D" (edi), "=&c" (ecx)
: "a" (c), "0" (s), "1" (count)
/* : no clobbers */
);
return edi;
}
static __always_inline
void *inlined_memchr_const_c(const void *s, int c, size_t count)
{
#if defined __OPTIMIZE__
void *edi;
int ecx, eax;
__asm__ __volatile__(
" jecxz 1f\n"
" movb %4, %%al\n" /* const c to %%al */
" repne; scasb\n"
" leal -1(%%edi), %%edi\n"
" je 2f\n"
"1:\n"
" xorl %%edi, %%edi\n"
"2:\n"
: "=&D" (edi), "=&c" (ecx), "=&a" (eax)
: "0" (s), "i" (c), "1" (count)
/* : no clobbers */
);
return edi;
#else
/* With -O0, gcc can't figure out how to encode CONST c
* as an immediate operand. Generating slightly bigger code
* (usually "movl CONST,%eax", 3 bytes bigger than needed):
*/
void *edi;
int ecx, eax;
__asm__ __volatile__(
" jecxz 1f\n"
" repne; scasb\n"
" leal -1(%%edi), %%edi\n"
" je 2f\n"
"1:\n"
" xorl %%edi, %%edi\n"
"2:\n"
: "=&D" (edi), "=&c" (ecx), "=&a" (eax)
: "0" (s), "2" (c), "1" (count)
/* : no clobbers */
);
return edi;
#endif
}
#if 1 /* +2 bytes on shared i386 build with gcc 4.3.0 */
#define memchr(s, c, count) ( \
__builtin_constant_p(c) \
? inlined_memchr_const_c(s, (c) & 0xff, count) \
: inlined_memchr(s, c, count) \
)
#endif
#endif /* _LIBC_STRING_i386_H */
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