kernel-ark/arch/tile/lib/string-endian.h
Chris Metcalf c53c70a90f tile: optimize and clean up string functions
This change cleans up the string code in a number of ways:

- For memcpy(), fix bug in prefetch and increase distance to 3 lines;
  optimize for unaligned data; do all loads before wh64 to make memcpy
  safe for forward-overlapping calls; etc.  Performance is improved.

- Use new copy_byte() function on tilegx to spread a single byte value
  out into a full word using the shufflebytes instruction.

- Clean up header include ordering to be more canonical, and remove
  spurious #undefs of function names.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2013-08-01 16:23:12 -04:00

45 lines
1.5 KiB
C

/*
* Copyright 2013 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* Provide a mask based on the pointer alignment that
* sets up non-zero bytes before the beginning of the string.
* The MASK expression works because shift counts are taken mod 64.
* Also, specify how to count "first" and "last" bits
* when the bits have been read as a word.
*/
#include <asm/byteorder.h>
#ifdef __LITTLE_ENDIAN
#define MASK(x) (__insn_shl(1ULL, (x << 3)) - 1)
#define NULMASK(x) ((2ULL << x) - 1)
#define CFZ(x) __insn_ctz(x)
#define REVCZ(x) __insn_clz(x)
#else
#define MASK(x) (__insn_shl(-2LL, ((-x << 3) - 1)))
#define NULMASK(x) (-2LL << (63 - x))
#define CFZ(x) __insn_clz(x)
#define REVCZ(x) __insn_ctz(x)
#endif
/*
* Create eight copies of the byte in a uint64_t. Byte Shuffle uses
* the bytes of srcB as the index into the dest vector to select a
* byte. With all indices of zero, the first byte is copied into all
* the other bytes.
*/
static inline uint64_t copy_byte(uint8_t byte)
{
return __insn_shufflebytes(byte, 0, 0);
}