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-rw-r--r--sysdeps/powerpc/powerpc32/strchr.S130
1 files changed, 130 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc32/strchr.S b/sysdeps/powerpc/powerpc32/strchr.S
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+/* Optimized strchr implementation for PowerPC.
+   Copyright (C) 1997, 1999, 2000 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 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., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <sysdep.h>
+#include <bp-sym.h>
+#include <bp-asm.h>
+
+/* See strlen.s for comments on how this works.  */
+
+/* char * [r3] strchr (const char *s [r3] , int c [r4] )  */
+
+ENTRY (BP_SYM (strchr))
+
+#define rTMP1	r0
+#define rRTN	r3	/* outgoing result */
+#if __BOUNDED_POINTERS__
+# define rSTR	r4
+# define rCHR	r5	/* byte we're looking for, spread over the whole word */
+# define rWORD	r8	/* the current word */
+#else
+# define rSTR	r8	/* current word pointer */
+# define rCHR	r4	/* byte we're looking for, spread over the whole word */
+# define rWORD	r5	/* the current word */
+#endif
+#define rCLZB	rCHR	/* leading zero byte count */
+#define rFEFE	r6	/* constant 0xfefefeff (-0x01010101) */
+#define r7F7F	r7	/* constant 0x7f7f7f7f */
+#define rTMP2	r9
+#define rIGN	r10	/* number of bits we should ignore in the first word */
+#define rMASK	r11	/* mask with the bits to ignore set to 0 */
+#define rTMP3	r12
+
+	CHECK_BOUNDS_LOW (rSTR, rTMP1, rTMP2)
+	STORE_RETURN_BOUNDS (rTMP1, rTMP2)
+
+	rlwimi	rCHR, rCHR, 8, 16, 23
+	li	rMASK, -1
+	rlwimi	rCHR, rCHR, 16, 0, 15
+	rlwinm	rIGN, rRTN, 3, 27, 28
+	lis	rFEFE, -0x101
+	lis	r7F7F, 0x7f7f
+	clrrwi	rSTR, rRTN, 2
+	addi	rFEFE, rFEFE, -0x101
+	addi	r7F7F, r7F7F, 0x7f7f
+/* Test the first (partial?) word.  */
+	lwz	rWORD, 0(rSTR)
+	srw	rMASK, rMASK, rIGN
+	orc	rWORD, rWORD, rMASK
+	add	rTMP1, rFEFE, rWORD
+	nor	rTMP2, r7F7F, rWORD
+	and.	rTMP1, rTMP1, rTMP2
+	xor	rTMP3, rCHR, rWORD
+	orc	rTMP3, rTMP3, rMASK
+	b	L(loopentry)
+
+/* The loop.  */
+
+L(loop):lwzu rWORD, 4(rSTR)
+	and.	rTMP1, rTMP1, rTMP2
+/* Test for 0.	*/
+	add	rTMP1, rFEFE, rWORD
+	nor	rTMP2, r7F7F, rWORD
+	bne	L(foundit)
+	and.	rTMP1, rTMP1, rTMP2
+/* Start test for the bytes we're looking for.  */
+	xor	rTMP3, rCHR, rWORD
+L(loopentry):
+	add	rTMP1, rFEFE, rTMP3
+	nor	rTMP2, r7F7F, rTMP3
+	beq	L(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.  */
+L(missed):
+	and.	rTMP1, rTMP1, rTMP2
+	li	rRTN, 0
+	STORE_RETURN_VALUE (rSTR)
+	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	rFEFE, r7F7F, rWORD
+	or	rMASK, r7F7F, rWORD
+	and	rTMP1, r7F7F, rTMP3
+	or	rIGN, r7F7F, rTMP3
+	add	rFEFE, rFEFE, r7F7F
+	add	rTMP1, rTMP1, r7F7F
+	nor	rWORD, rMASK, rFEFE
+	nor	rTMP2, rIGN, rTMP1
+	cmplw	rWORD, rTMP2
+	bgtlr
+	cntlzw	rCLZB, rTMP2
+	srwi	rCLZB, rCLZB, 3
+	add	rRTN, rSTR, rCLZB
+	CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
+	STORE_RETURN_VALUE (rSTR)
+	blr
+
+L(foundit):
+	and	rTMP1, r7F7F, rTMP3
+	or	rIGN, r7F7F, rTMP3
+	add	rTMP1, rTMP1, r7F7F
+	nor	rTMP2, rIGN, rTMP1
+	cntlzw	rCLZB, rTMP2
+	subi	rSTR, rSTR, 4
+	srwi	rCLZB, rCLZB, 3
+	add	rRTN, rSTR, rCLZB
+	CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
+	STORE_RETURN_VALUE (rSTR)
+	blr
+END (BP_SYM (strchr))
+
+weak_alias (BP_SYM (strchr), BP_SYM (index))