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+ # Optimized strchr implementation for PowerPC.
+ # Copyright (C) 1997 Free Software Foundation, Inc.
+ # 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., 59 Temple Place - Suite 330,
+ # Boston, MA 02111-1307, USA.
+
+ # See strlen.s for comments on how this works.
+
+ .section ".text"
+ .align 2
+ .globl strchr
+ .type strchr,@function
+strchr:
+ # char * [r3] strchr (const char *s [r3] , int c [r4] )
+
+ # r0: a temporary
+ # r3: our return result.
+ # r4: byte we're looking for, spread over the whole word
+ # r5: the current word
+ # r6: the constant 0xfefefeff (-0x01010101)
+ # r7: the constant 0x7f7f7f7f
+ # r8: pointer to the current word.
+ # r9: a temporary
+ # r10: the number of bits we should ignore in the first word
+ # r11: a mask with the bits to ignore set to 0
+ # r12: a temporary
+
+ rlwimi %r4,%r4,8,16,23
+ li %r11,-1
+ rlwimi %r4,%r4,16,0,15
+ lis %r6,0xfeff
+ lis %r7,0x7f7f
+ clrrwi %r8,%r3,2
+ addi %r7,%r7,0x7f7f
+ addi %r6,%r6,0xfffffeff
+ rlwinm %r10,%r3,3,27,28
+ # Test the first (partial?) word.
+ lwz %r5,0(%r8)
+ srw %r11,%r11,%r10
+ orc %r5,%r5,%r11
+ add %r0,%r6,%r5
+ nor %r9,%r7,%r5
+ and. %r0,%r0,%r9
+ xor %r12,%r4,%r5
+ orc %r12,%r12,%r11
+ b loopentry
+
+ # The loop.
+
+loop: lwzu %r5,4(%r8)
+ and. %r0,%r0,%r9
+ # Test for 0
+ add %r0,%r6,%r5
+ nor %r9,%r7,%r5
+ bne foundit
+ and. %r0,%r0,%r9
+ # Start test for the bytes we're looking for
+ xor %r12,%r4,%r5
+loopentry:
+ add %r0,%r6,%r12
+ nor %r9,%r7,%r12
+ beq loop
+ # There is a zero byte in the word, but may also be a matching byte (either
+ # before or after the zero byte). In fact, we may be looking for a
+ # zero byte, in which case we return a match. We guess that this hasn't
+ # happened, though.
+missed:
+ and. %r0,%r0,%r9
+ li %r3,0
+ beqlr
+ # It did happen. Decide which one was first...
+ # I'm not sure if this is actually faster than a sequence of
+ # rotates, compares, and branches (we use it anyway because it's shorter).
+ and %r6,%r7,%r5
+ or %r11,%r7,%r5
+ and %r0,%r7,%r12
+ or %r10,%r7,%r12
+ add %r6,%r6,%r7
+ add %r0,%r0,%r7
+ nor %r5,%r11,%r6
+ nor %r9,%r10,%r0
+ cmplw %r5,%r9
+ bgtlr
+ cntlzw %r4,%r9
+ srwi %r4,%r4,3
+ add %r3,%r8,%r4
+ blr
+
+foundit:
+ and %r0,%r7,%r12
+ or %r10,%r7,%r12
+ add %r0,%r0,%r7
+ nor %r9,%r10,%r0
+ cntlzw %r4,%r9
+ subi %r8,%r8,4
+ srwi %r4,%r4,3
+ add %r3,%r8,%r4
+ blr
+
+0:
+ .size strchr,0b-strchr
+
+ .globl index
+ .weak index
+ .set index,strchr