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| /* SPDX-License-Identifier: GPL-2.0 */
| /*
| * arch/alpha/lib/strncpy.S
| * Contributed by Richard Henderson (rth@tamu.edu)
| *
| * Copy no more than COUNT bytes of the null-terminated string from
| * SRC to DST. If SRC does not cover all of COUNT, the balance is
| * zeroed.
| *
| * Or, rather, if the kernel cared about that weird ANSI quirk. This
| * version has cropped that bit o' nastiness as well as assuming that
| * __stxncpy is in range of a branch.
| */
| #include <asm/export.h>
| .set noat
| .set noreorder
|
| .text
|
| .align 4
| .globl strncpy
| .ent strncpy
| strncpy:
| .frame $30, 0, $26
| .prologue 0
|
| mov $16, $0 # set return value now
| beq $18, $zerolen
| unop
| bsr $23, __stxncpy # do the work of the copy
|
| unop
| bne $18, $multiword # do we have full words left?
| subq $24, 1, $3 # nope
| subq $27, 1, $4
|
| or $3, $24, $3 # clear the bits between the last
| or $4, $27, $4 # written byte and the last byte in COUNT
| andnot $3, $4, $4
| zap $1, $4, $1
|
| stq_u $1, 0($16)
| ret
|
| .align 4
| $multiword:
| subq $27, 1, $2 # clear the final bits in the prev word
| or $2, $27, $2
| zapnot $1, $2, $1
| subq $18, 1, $18
|
| stq_u $1, 0($16)
| addq $16, 8, $16
| unop
| beq $18, 1f
|
| nop
| unop
| nop
| blbc $18, 0f
|
| stq_u $31, 0($16) # zero one word
| subq $18, 1, $18
| addq $16, 8, $16
| beq $18, 1f
|
| 0: stq_u $31, 0($16) # zero two words
| subq $18, 2, $18
| stq_u $31, 8($16)
| addq $16, 16, $16
| bne $18, 0b
|
| 1: ldq_u $1, 0($16) # clear the leading bits in the final word
| subq $24, 1, $2
| or $2, $24, $2
|
| zap $1, $2, $1
| stq_u $1, 0($16)
| $zerolen:
| ret
|
| .end strncpy
| EXPORT_SYMBOL(strncpy)
|
|
