diff options
Diffstat (limited to 'sysdeps/alpha')
| -rw-r--r-- | sysdeps/alpha/memchr.S | 163 | ||||
| -rw-r--r-- | sysdeps/alpha/memchr.c | 86 |
2 files changed, 163 insertions, 86 deletions
diff --git a/sysdeps/alpha/memchr.S b/sysdeps/alpha/memchr.S new file mode 100644 index 0000000000..118a1f13d1 --- /dev/null +++ b/sysdeps/alpha/memchr.S @@ -0,0 +1,163 @@ +/* Copyright (C) 1996 Free Software Foundation, Inc. + Contributed by David Mosberger (davidm@cs.arizona.edu). + +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +/* Finds characters in a memory area. Optimized for the Alpha +architecture: + + - memory accessed as aligned quadwords only + - uses cmpbge to compare 8 bytes in parallel + - does binary search to find 0 byte in last + quadword (HAKMEM needed 12 instructions to + do this instead of the 9 instructions that + binary search needs). + +For correctness consider that: + + - only minimum number of quadwords may be accessed + - the third argument is an unsigned long +*/ + +#include <sysdep.h> +#ifdef __linux__ +# include <alpha/regdef.h> +#else +#include <regdef.h> +#endif + + .set noreorder + .set noat + +ENTRY(memchr) + beq a2, not_found + ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned) + addq a0, a2, t4 + and a1, 0xff, a1 # a1 = 00000000000000ch + ldq_u t5, -1(t4) + sll a1, 8, t1 # t1 = 000000000000ch00 + cmpult a2, 9, t3 + or t1, a1, a1 # a1 = 000000000000chch + sll a1, 16, t1 # t1 = 00000000chch0000 + lda t2, -1(zero) + or t1, a1, a1 # a1 = 00000000chchchch + sll a1, 32, t1 # t1 = chchchch00000000 + extql t0, a0, t6 + or t1, a1, a1 # a1 = chchchchchchchch + + beq t3, first_quad + + extqh t5, a0, t5 + mov a0, v0 + or t6, t5, t0 # t0 = quadword starting at a0 + + # + # Deal with the case where at most 8 bytes remain to be searched + # in t0. E.g.: + # a2 = 6 + # t0 = ????c6c5c4c3c2c1 +last_quad: + negq a2, t5 + srl t2, t5, t5 # t5 = mask of a2 bits set + xor a1, t0, t0 + cmpbge zero, t0, t1 + and t1, t5, t1 + beq t1, not_found + +found_it: + # now, determine which byte matched: + negq t1, t2 + and t1, t2, t1 + + and t1, 0x0f, t0 + addq v0, 4, t2 + cmoveq t0, t2, v0 + + and t1, 0x33, t0 + addq v0, 2, t2 + cmoveq t0, t2, v0 + + and t1, 0x55, t0 + addq v0, 1, t2 + cmoveq t0, t2, v0 + +done: ret + + + # + # Deal with the case where a2 > 8 bytes remain to be + # searched. a0 may not be aligned. + # +first_quad: + andnot a0, 0x7, v0 + insqh t2, a0, t1 # t1 = 0000ffffffffffff (a0<0:2> ff bytes) + xor t0, a1, t0 + or t0, t1, t0 # t0 = ====ffffffffffff + cmpbge zero, t0, t1 + bne t1, found_it + + /* at least one byte left to process */ + + ldq t0, 8(v0) + addq v0, 8, v0 + /* + * Make a2 point to last quad to be accessed (the + * last quad may or may not be partial). + */ + subq t4, 1, a2 + andnot a2, 0x7, a2 + cmpult v0, a2, t1 + beq t1, final + + /* at least two quads remain to be accessed */ + + subq a2, v0, t3 # t3 <- number of quads to be processed in loop + and t3, 8, t3 # odd number of quads? + bne t3, odd_quad_count + + /* at least three quads remain to be accessed */ + + mov t0, t3 # move prefetched value into correct register + + .align 3 +unrolled_loop: + ldq t0, 8(v0) # prefetch t0 + xor a1, t3, t1 + cmpbge zero, t1, t1 + bne t1, found_it + + addq v0, 8, v0 +odd_quad_count: + xor a1, t0, t1 + ldq t3, 8(v0) # prefetch t3 + cmpbge zero, t1, t1 + bne t1, found_it + + addq v0, 8, v0 + cmpult v0, a2, t5 + bne t5, unrolled_loop + + mov t3, t0 # move prefetched value into t0 +final: subq t4, v0, a2 # a2 <- number of bytes left to do + bne a2, last_quad + +not_found: + mov zero, v0 + ret + + .end memchr diff --git a/sysdeps/alpha/memchr.c b/sysdeps/alpha/memchr.c deleted file mode 100644 index a911302ea6..0000000000 --- a/sysdeps/alpha/memchr.c +++ /dev/null @@ -1,86 +0,0 @@ -/* Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc. - -The GNU C Library is free software; you can redistribute it and/or -modify it under the terms of the GNU Library General Public License as -published by the Free Software Foundation; either version 2 of the -License, or (at your option) any later version. - -The GNU C Library is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU -Library General Public License for more details. - -You should have received a copy of the GNU Library General Public -License along with the GNU C Library; see the file COPYING.LIB. If -not, write to the Free Software Foundation, Inc., 675 Mass Ave, -Cambridge, MA 02139, USA. */ - -#include <string.h> - -/* Search no more than N bytes of S for C. */ - -void * -memchr (const void *s, int c, size_t n) -{ - const char *char_ptr; - const unsigned long int *longword_ptr; - unsigned long int charmask; - size_t x; - - c = (unsigned char) c; - - /* Handle the first few characters by reading one character at a time. - Do this until STR is aligned on a 8-byte border. */ - for (char_ptr = s; n > 0 && ((unsigned long int) char_ptr & 7) != 0; - --n, ++char_ptr) - if (*char_ptr == c) - return (void *) char_ptr; - - if (n == (size_t)0) - return NULL; - - x = n; - - longword_ptr = (unsigned long int *) char_ptr; - - /* Set up a longword, each of whose bytes is C. */ - charmask = c | (c << 8); - charmask |= charmask << 16; - charmask |= charmask << 32; - - for (;;) - { - const unsigned long int longword = *longword_ptr++; - int ge, le; - - if (x < 4) - x = (size_t) 0; - else - x -= 4; - - /* Set bits in GE if bytes in CHARMASK are >= bytes in LONGWORD. */ - asm ("cmpbge %1, %2, %0" : "=r" (ge) : "r" (charmask), "r" (longword)); - - /* Set bits in LE if bytes in CHARMASK are <= bytes in LONGWORD. */ - asm ("cmpbge %2, %1, %0" : "=r" (le) : "r" (charmask), "r" (longword)); - - /* Bytes that are both <= and >= are == to C. */ - if (ge & le) - { - /* Which of the bytes was the C? */ - - unsigned char *cp = (unsigned char *) (longword_ptr - 1); - int i; - - for (i = 0; i < 7; i++) - if (cp[i] == c) - return &cp[i]; - return &cp[7]; - } - - if (x == (size_t)0) - break; - } - - return NULL; -} |