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| /* SPDX-License-Identifier: GPL-2.0 */
| /*
| * 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.
| */
|
| #include <asm/export.h>
| .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
| EXPORT_SYMBOL(strcat)
|
|
