1 files changed, 84 insertions, 0 deletions

diff --git a/arch/alpha/lib/strncat.S b/arch/alpha/lib/strncat.S
new file mode 100644
index 000000000000..a8278163c972
--- /dev/null
+++ b/arch/alpha/lib/strncat.S
@@ -0,0 +1,84 @@
+/*
+ * 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.
+ */
+
+        .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