1 files changed, 94 insertions, 0 deletions
diff --git a/arch/alpha/lib/ev67-strncat.S b/arch/alpha/lib/ev67-strncat.S
new file mode 100644
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+++ b/arch/alpha/lib/ev67-strncat.S
@@ -0,0 +1,94 @@
+/*
+ * arch/alpha/lib/ev67-strncat.S
+ * 21264 version contributed by Rick Gorton <rick.gorton@api-networks.com>
+ *
+ * Append no more than COUNT characters from the null-terminated string SRC
+ * to the null-terminated string DST.  Always null-terminate the new DST.
+ *
+ * This differs slightly from the semantics in libc in that we never write
+ * past count, whereas libc may write to count+1.  This follows the generic
+ * implementation in lib/string.c and is, IMHO, more sensible.
+ *
+ * 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.
+ */
+
+
+	.text
+
+	.align 4
+	.globl strncat
+	.ent strncat
+strncat:
+	.frame $30, 0, $26
+	.prologue 0
+
+	mov	$16, $0		# set up return value
+	beq	$18, $zerocount	# U :
+	/* Find the end of the string.  */
+	ldq_u   $1, 0($16)	# L : load first quadword ($16 may be misaligned)
+	lda     $2, -1($31)	# E :
+
+	insqh   $2, $0, $2	# U :
+	andnot  $16, 7, $16	# E :
+	nop			# E :
+	or      $2, $1, $1	# E :
+
+	nop			# E :
+	nop			# E :
+	cmpbge  $31, $1, $2	# E : bits set iff byte == 0
+	bne     $2, $found	# U :
+
+$loop:	ldq     $1, 8($16)	# L :
+	addq    $16, 8, $16	# E :
+	cmpbge  $31, $1, $2	# E :
+	beq     $2, $loop	# U :
+
+$found:	cttz	$2, $3		# U0 :
+	addq	$16, $3, $16	# E :
+	nop			# E :
+	bsr	$23, __stxncpy	# L0 :/* Now do the append.  */
+
+	/* Worry about the null termination.  */
+
+	zapnot	$1, $27, $2	# U : was last byte a null?
+	cmplt	$27, $24, $5	# E : did we fill the buffer completely?
+	bne	$2, 0f		# U :
+	ret			# L0 :
+
+0:	or	$5, $18, $2	# E :
+	nop
+	bne	$2, 2f		# U :
+	and	$24, 0x80, $3	# E : no zero next byte
+
+	nop			# E :
+	bne	$3, 1f		# U :
+	/* Here there are bytes left in the current word.  Clear one.  */
+	addq	$24, $24, $24	# E : end-of-count bit <<= 1
+	nop			# E :
+
+2:	zap	$1, $24, $1	# U :
+	nop			# E :
+	stq_u	$1, 0($16)	# L :
+	ret			# L0 :
+
+1:	/* Here we must clear the first byte of the next DST word */
+	stb	$31, 8($16)	# L :
+	nop			# E :
+	nop			# E :
+	ret			# L0 :
+
+$zerocount:
+	nop			# E :
+	nop			# E :
+	nop			# E :
+	ret			# L0 :
+
+	.end strncat