/* * arch/alpha/lib/strrchr.S * Contributed by Richard Henderson (rth@tamu.edu) * * Return the address of the last occurrance of a given character * within a null-terminated string, or null if it is not found. */#include <alpha/regdef.h>	.set noreorder	.set noat	.align 3	.ent strrchr	.globl strrchrstrrchr:	.frame sp, 0, ra	.prologue 0	zapnot	a1, 1, a1	# e0    : zero extend our test character	mov	zero, t6	# .. e1 : t6 is last match aligned addr	sll	a1, 8, t5	# e0    : replicate our test character	mov	zero, t8	# .. e1 : t8 is last match byte compare mask	or	t5, a1, a1	# e0    :	ldq_u   t0, 0(a0)	# .. e1 : load first quadword	sll	a1, 16, t5	# e0    :	andnot  a0, 7, v0	# .. e1 : align source addr	or	t5, a1, a1	# e0    :	lda	t4, -1		# .. e1 : build garbage mask	sll	a1, 32, t5	# e0    :	cmpbge  zero, t0, t1	# .. e1 : bits set iff byte == zero	mskqh	t4, a0, t4	# e0    :	or	t5, a1, a1	# .. e1 : character replication complete	xor	t0, a1, t2	# e0    : make bytes == c zero	cmpbge	zero, t4, t4	# .. e1 : bits set iff byte is garbage	cmpbge  zero, t2, t3	# e0    : bits set iff byte == c	andnot	t1, t4, t1	# .. e1 : clear garbage from null test	andnot	t3, t4, t3	# e0    : clear garbage from char test	bne	t1, $eos	# .. e1 : did we already hit the terminator?	/* Character search main loop */$loop:	ldq	t0, 8(v0)	# e0    : load next quadword	cmovne	t3, v0, t6	# .. e1 : save previous comparisons match	cmovne	t3, t3, t8	# e0    :	addq	v0, 8, v0	# .. e1 :	xor	t0, a1, t2	# e0    :	cmpbge	zero, t0, t1	# .. e1 : bits set iff byte == zero	cmpbge	zero, t2, t3	# e0    : bits set iff byte == c	beq	t1, $loop	# .. e1 : if we havnt seen a null, loop	/* Mask out character matches after terminator */$eos:	negq	t1, t4		# e0    : isolate first null byte match	and	t1, t4, t4	# e1    :	subq	t4, 1, t5	# e0    : build a mask of the bytes upto...	or	t4, t5, t4	# e1    : ... and including the null	and	t3, t4, t3	# e0    : mask out char matches after null	cmovne	t3, t3, t8	# .. e1 : save it, if match found	cmovne	t3, v0, t6	# e0    :	/* Locate the address of the last matched character */	/* Retain the early exit for the ev4 -- the ev5 mispredict penalty	   is 5 cycles -- the same as just falling through.  */	beq	t8, $retnull	# .. e1 :	and	t8, 0xf0, t2	# e0    : binary search for the high bit set	cmovne	t2, t2, t8	# .. e1 (zdb)	cmovne	t2, 4, t2	# e0    :	and	t8, 0xcc, t1	# .. e1 :	cmovne	t1, t1, t8	# e0    :	cmovne	t1, 2, t1	# .. e1 :	and	t8, 0xaa, t0	# e0    :	cmovne	t0, 1, t0	# .. e1 (zdb)	addq	t2, t1, t1	# e0    :	addq	t6, t0, v0	# .. e1 : add our aligned base ptr to the mix	addq	v0, t1, v0	# e0    :	ret			# .. e1 :$retnull:	mov	zero, v0	# e0    :	ret			# .. e1 :	.end strrchr