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+/* Optimized memchr implementation for PowerPC64/POWER7 using cmpb insn.
+ Copyright (C) 2010 Free Software Foundation, Inc.
+ Contributed by Luis Machado <luisgpm@br.ibm.com>.
+ 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 Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA
+ 02110-1301 USA. */
+
+#include <sysdep.h>
+#include <bp-sym.h>
+#include <bp-asm.h>
+
+/* int [r3] memchr (char *s [r3], int byte [r4], int size [r5]) */
+ .machine power7
+ENTRY (BP_SYM (__memchr))
+ CALL_MCOUNT 2
+ dcbt 0,r3
+ clrrdi r8,r3,3
+ rlwimi r4,r4,8,16,23
+ rlwimi r4,r4,16,0,15
+ insrdi r4,r4,32,0
+ add r7,r3,r5 /* Calculate the last acceptable address. */
+ cmpldi r5,32
+ ble L(small_range)
+
+ cmpld cr7,r3,r7 /* Is the address equal or less than r3? If
+ it's equal or less, it means size is either 0
+ or a negative number. */
+ ble cr7,L(proceed)
+
+ li r7,-1 /* Make r11 the biggest if r4 <= 0. */
+L(proceed):
+ rlwinm r6,r3,3,26,28 /* Calculate padding. */
+ ld r12,0(r8) /* Load doubleword from memory. */
+ cmpb r10,r12,r4 /* Check for BYTE's in DWORD1. */
+ sld r10,r10,r6
+ srd r10,r10,r6
+ cmpldi cr7,r10,0 /* If r10 == 0, no BYTE's's have been found. */
+ bne cr7,L(done)
+
+ /* Are we done already? */
+ addi r9,r8,8
+ cmpld cr6,r9,r7
+ bge cr6,L(null)
+
+ mtcrf 0x01,r8
+ /* Are we now aligned to a quadword boundary? If so, skip to
+ the main loop. Otherwise, go through the alignment code. */
+
+ bt 28,L(loop_setup)
+
+ /* Handle DWORD2 of pair. */
+ ldu r12,8(r8)
+ cmpb r10,r12,r4
+ cmpldi cr7,r10,0
+ bne cr7,L(done)
+
+ /* Are we done already? */
+ addi r9,r8,8
+ cmpld cr6,r9,r7
+ bge cr6,L(null)
+
+L(loop_setup):
+ sub r5,r7,r9
+ srdi r6,r5,4 /* Number of loop iterations. */
+ mtctr r6 /* Setup the counter. */
+ b L(loop)
+ /* Main loop to look for BYTE backwards in the string. Since
+ it's a small loop (< 8 instructions), align it to 32-bytes. */
+ .p2align 5
+L(loop):
+ /* Load two doublewords, compare and merge in a
+ single register for speed. This is an attempt
+ to speed up the byte-checking process for bigger strings. */
+
+ ld r12,8(r8)
+ ldu r11,16(r8)
+ cmpb r10,r12,r4
+ cmpb r9,r11,r4
+ or r5,r9,r10 /* Merge everything in one doubleword. */
+ cmpldi cr7,r5,0
+ bne cr7,L(found)
+ bdnz L(loop)
+ /* We're here because the counter reached 0, and that means we
+ didn't have any matches for BYTE in the whole range. Just return
+ the original range. */
+ addi r9,r8,8
+ cmpld cr6,r9,r7
+ blt cr6,L(loop_small)
+ b L(null)
+
+ /* OK, one (or both) of the doublewords contains BYTE. Check
+ the first doubleword and decrement the address in case the first
+ doubleword really contains BYTE. */
+ .align 4
+L(found):
+ cmpldi cr6,r10,0
+ addi r8,r8,-8
+ bne cr6,L(done)
+
+ /* BYTE must be in the second doubleword. Adjust the address
+ again and move the result of cmpb to r10 so we can calculate the
+ pointer. */
+
+ mr r10,r9
+ addi r8,r8,8
+
+ /* r10 has the output of the cmpb instruction, that is, it contains
+ 0xff in the same position as BYTE in the original
+ doubleword from the string. Use that to calculate the pointer.
+ We need to make sure BYTE is *before* the end of the
+ range. */
+L(done):
+ cntlzd r0,r10 /* Count leading zeroes before the match. */
+ srdi r0,r0,3 /* Convert leading zeroes to bytes. */
+ add r3,r8,r0
+ cmpld r3,r7
+ bge L(null)
+ blr
+
+ .align 4
+L(null):
+ li r3,0
+ blr
+
+/* Deals with size <= 32. */
+ .align 4
+L(small_range):
+ cmpldi r5,0
+ beq L(null)
+
+ rlwinm r6,r3,3,26,28 /* Calculate padding. */
+ ld r12,0(r8) /* Load word from memory. */
+ cmpb r10,r12,r4 /* Check for BYTE in DWORD1. */
+ sld r10,r10,r6
+ srd r10,r10,r6
+ cmpldi cr7,r10,0
+ bne cr7,L(done)
+
+ /* Are we done already? */
+ addi r9,r8,8
+ cmpld r9,r7
+ bge L(null)
+ b L(loop_small)
+
+ .p2align 5
+L(loop_small):
+ ldu r12,8(r8)
+ cmpb r10,r12,r4
+ addi r9,r8,8
+ cmpldi cr6,r10,0
+ bne cr6,L(done)
+ cmpld r9,r7
+ bge L(null)
+ b L(loop_small)
+
+END (BP_SYM (__memchr))
+weak_alias (BP_SYM (__memchr), BP_SYM(memchr))
+libc_hidden_builtin_def (memchr)