/* * arch/alpha/lib/ev67-strchr.S * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com> * * Return the address of a given character within a null-terminated * string, or null if it is not found. * * Much of the information about 21264 scheduling/coding comes from: *	Compiler Writer's Guide for the Alpha 21264 *	abbreviated as 'CWG' in other comments here *	ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html * Scheduling notation: *	E	- either cluster *	U	- upper subcluster; U0 - subcluster U0; U1 - subcluster U1 *	L	- lower subcluster; L0 - subcluster L0; L1 - subcluster L1 * Try not to change the actual algorithm if possible for consistency. */#include <asm/regdef.h>	.set noreorder	.set noat	.align 4	.globl strchr	.ent strchrstrchr:	.frame sp, 0, ra	.prologue 0	ldq_u   t0, 0(a0)	# L : load first quadword Latency=3	and	a1, 0xff, t3	# E : 00000000000000ch	insbl	a1, 1, t5	# U : 000000000000ch00	insbl	a1, 7, a2	# U : ch00000000000000	insbl	t3, 6, a3	# U : 00ch000000000000	or	t5, t3, a1	# E : 000000000000chch	andnot  a0, 7, v0	# E : align our loop pointer	lda	t4, -1		# E : build garbage mask	mskqh	t4, a0, t4	# U : only want relevant part of first quad	or	a2, a3, a2	# E : chch000000000000	inswl	a1, 2, t5	# E : 00000000chch0000	inswl	a1, 4, a3	# E : 0000chch00000000	or	a1, a2, a1	# E : chch00000000chch	or	a3, t5, t5	# E : 0000chchchch0000	cmpbge  zero, t0, t2	# E : bits set iff byte == zero	cmpbge	zero, t4, t4	# E : bits set iff byte is garbage	/* This quad is _very_ serialized.  Lots of stalling happens */	or	t5, a1, a1	# E : chchchchchchchch	xor	t0, a1, t1	# E : make bytes == c zero	cmpbge  zero, t1, t3	# E : bits set iff byte == c	or	t2, t3, t0	# E : bits set iff char match or zero match	andnot	t0, t4, t0	# E : clear garbage bits	cttz	t0, a2		# U0 : speculative (in case we get a match)	nop			# E :	bne	t0, $found	# U :	/*	 * Yuk.  This loop is going to stall like crazy waiting for the	 * data to be loaded.  Not much can be done about it unless it's	 * unrolled multiple times - is that safe to do in kernel space?	 * Or would exception handling recovery code do the trick here?	 */$loop:	ldq	t0, 8(v0)	# L : Latency=3	addq	v0, 8, v0	# E :	xor	t0, a1, t1	# E :	cmpbge	zero, t0, t2	# E : bits set iff byte == 0	cmpbge	zero, t1, t3	# E : bits set iff byte == c	or	t2, t3, t0	# E :	cttz	t3, a2		# U0 : speculative (in case we get a match)	beq	t0, $loop	# U :$found:	negq    t0, t1		# E : clear all but least set bit	and     t0, t1, t0	# E :	and	t0, t3, t1	# E : bit set iff byte was the char	addq	v0, a2, v0	# E : Add in the bit number from above	cmoveq	t1, $31, v0	# E : Two mapping slots, latency = 2	nop	nop	ret			# L0 :	.end strchr