/*
* 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.
*/
.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 $4, $3, $4
zap $1, $4, $1
stq_u $1, 0($16)
ret
.align 4
$multiword:
subq $24, 1, $2 # clear the final bits in the prev word
or $2, $24, $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 $27, 1, $2
or $2, $27, $2
zap $1, $2, $1
stq_u $1, 0($16)
$zerolen:
ret
.end strncpy
