patch-2.1.5 linux/arch/alpha/lib/strchr.S

• Lines: 71
• Date: Fri Oct 18 11:53:20 1996
• Orig file: v2.1.4/linux/arch/alpha/lib/strchr.S
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.4/linux/arch/alpha/lib/strchr.S linux/arch/alpha/lib/strchr.S
@@ -0,0 +1,70 @@
+/*
+ * arch/alpha/lib/strchr.S
+ * Contributed by Richard Henderson (rth@tamu.edu)
+ *
+ * Return the address 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
+	.globl strchr
+	.ent strchr
+strchr:
+	.frame sp, 0, ra
+	.prologue 0
+
+	zapnot	a1, 1, a1	# e0    : zero extend the search character
+	ldq_u   t0, 0(a0)	# .. e1 : load first quadword
+	sll	a1, 8, t5	# e0    : replicate the search character
+	andnot  a0, 7, v0	# .. e1 : align our loop pointer
+	or	t5, a1, a1	# e0    :
+	lda	t4, -1		# .. e1 : build garbage mask
+	sll	a1, 16, t5	# e0    :
+	cmpbge  zero, t0, t2	# .. e1 : bits set iff byte == zero
+	mskqh	t4, a0, t4	# e0    :
+	or	t5, a1, a1	# .. e1 :
+	sll	a1, 32, t5	# e0    :
+	cmpbge	zero, t4, t4	# .. e1 : bits set iff byte is garbage
+	or	t5, a1, a1	# e0    :
+	xor	t0, a1, t1	# .. e1 : make bytes == c zero
+	cmpbge  zero, t1, t3	# e0    : bits set iff byte == c
+	or	t2, t3, t0	# e1    : bits set iff char match or zero match
+	andnot	t0, t4, t0	# e0    : clear garbage bits
+	bne	t0, $found	# .. e1 (zdb)
+
+$loop:	ldq	t0, 8(v0)	# e0    :
+	addq	v0, 8, v0	# .. e1 :
+	nop			# e0    :
+	xor	t0, a1, t1	# .. e1 (ev5 data stall)
+	cmpbge	zero, t0, t2	# e0    : bits set iff byte == 0
+	cmpbge	zero, t1, t3	# .. e1 : bits set iff byte == c
+	or	t2, t3, t0	# e0    :
+	beq	t0, $loop	# .. e1 (zdb)
+
+$found:	negq    t0, t1		# e0    : clear all but least set bit
+	and     t0, t1, t0	# e1 (stall)
+
+	and	t0, t3, t1	# e0    : bit set iff byte was the char
+	beq	t1, $retnull	# .. e1 (zdb)
+
+	and     t0, 0xf0, t2	# e0    : binary search for that set bit
+	and	t0, 0xcc, t3	# .. e1 :
+	and	t0, 0xaa, t4	# e0    :
+	cmovne	t2, 4, t2	# .. e1 :
+	cmovne	t3, 2, t3	# e0    :
+	cmovne	t4, 1, t4	# .. e1 :
+	addq	t2, t3, t2	# e0    :
+	addq	v0, t4, v0	# .. e1 :
+	addq	v0, t2, v0	# e0    :
+	ret			# .. e1 :
+
+$retnull:
+	mov	zero, v0	# e0    :
+	ret			# .. e1 :
+
+	.end strchr