/*
   * arch/alpha/lib/ev67-strcat.S
   * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
   *
   * Append a null-terminated string from SRC to DST.
   *
   * 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.
   * Commentary: It seems bogus to walk the input string twice - once
   * to determine the length, and then again while doing the copy.
   * A significant (future) enhancement would be to only read the input
   * string once.
   */
  
  
  	.text
  
  	.align 4
  	.globl strcat
  	.ent strcat
  strcat:
  	.frame $30, 0, $26
  	.prologue 0
  
  	mov	$16, $0		# E : set up return value
  	/* Find the end of the string.  */
  	ldq_u   $1, 0($16)	# L : load first quadword (a0 may be misaligned)
  	lda     $2, -1		# E :
  	insqh   $2, $16, $2	# U :
  
  	andnot  $16, 7, $16	# E :
  	or      $2, $1, $1	# 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 :
  	/* Now do the append.  */
  	mov	$26, $23	# E :
  	br	__stxcpy	# L0 :
  
  	.end strcat