85 lines
1.8 KiB
ArmAsm
85 lines
1.8 KiB
ArmAsm
/*
|
|
* 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)
|