| /* 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) |
