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| /* SPDX-License-Identifier: GPL-2.0 */
| /*
| * arch/alpha/lib/strncat.S
| * Contributed by Richard Henderson (rth@tamu.edu)
| *
| * 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.
| */
| #include <asm/export.h>
| .text
|
| .align 3
| .globl strncat
| .ent strncat
| strncat:
| .frame $30, 0, $26
| .prologue 0
|
| mov $16, $0 # set up return value
| beq $18, $zerocount
|
| /* Find the end of the string. */
|
| ldq_u $1, 0($16) # load first quadword ($16 may be misaligned)
| lda $2, -1($31)
| insqh $2, $16, $2
| andnot $16, 7, $16
| or $2, $1, $1
| cmpbge $31, $1, $2 # bits set iff byte == 0
| bne $2, $found
|
| $loop: ldq $1, 8($16)
| addq $16, 8, $16
| cmpbge $31, $1, $2
| beq $2, $loop
|
| $found: negq $2, $3 # clear all but least set bit
| and $2, $3, $2
|
| and $2, 0xf0, $3 # binary search for that set bit
| and $2, 0xcc, $4
| and $2, 0xaa, $5
| cmovne $3, 4, $3
| cmovne $4, 2, $4
| cmovne $5, 1, $5
| addq $3, $4, $3
| addq $16, $5, $16
| addq $16, $3, $16
|
| /* Now do the append. */
|
| bsr $23, __stxncpy
|
| /* Worry about the null termination. */
|
| zapnot $1, $27, $2 # was last byte a null?
| bne $2, 0f
| ret
|
| 0: cmplt $27, $24, $2 # did we fill the buffer completely?
| or $2, $18, $2
| bne $2, 2f
|
| and $24, 0x80, $2 # no zero next byte
| bne $2, 1f
|
| /* Here there are bytes left in the current word. Clear one. */
| addq $24, $24, $24 # end-of-count bit <<= 1
| 2: zap $1, $24, $1
| stq_u $1, 0($16)
| ret
|
| 1: /* Here we must read the next DST word and clear the first byte. */
| ldq_u $1, 8($16)
| zap $1, 1, $1
| stq_u $1, 8($16)
|
| $zerocount:
| ret
|
| .end strncat
| EXPORT_SYMBOL(strncat)
|
|
