diff options
Diffstat (limited to 'arch/alpha/lib/strncpy.S')
| -rw-r--r-- | arch/alpha/lib/strncpy.S | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/arch/alpha/lib/strncpy.S b/arch/alpha/lib/strncpy.S new file mode 100644 index 000000000..cc57fad8b --- /dev/null +++ b/arch/alpha/lib/strncpy.S @@ -0,0 +1,83 @@ +/* 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) |