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Chris Zankel9a8fd552005-06-23 22:01:26 -07001/*
2 * include/asm-xtensa/byteorder.h
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2001 - 2005 Tensilica Inc.
9 */
10
11#ifndef _XTENSA_BYTEORDER_H
12#define _XTENSA_BYTEORDER_H
13
14#include <asm/processor.h>
15#include <asm/types.h>
16
17static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
18{
19 __u32 res;
20 /* instruction sequence from Xtensa ISA release 2/2000 */
21 __asm__("ssai 8 \n\t"
22 "srli %0, %1, 16 \n\t"
23 "src %0, %0, %1 \n\t"
24 "src %0, %0, %0 \n\t"
25 "src %0, %1, %0 \n"
26 : "=&a" (res)
27 : "a" (x)
28 );
29 return res;
30}
31
32static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
33{
34 /* Given that 'short' values are signed (i.e., can be negative),
35 * we cannot assume that the upper 16-bits of the register are
36 * zero. We are careful to mask values after shifting.
37 */
38
39 /* There exists an anomaly between xt-gcc and xt-xcc. xt-gcc
40 * inserts an extui instruction after putting this function inline
41 * to ensure that it uses only the least-significant 16 bits of
42 * the result. xt-xcc doesn't use an extui, but assumes the
43 * __asm__ macro follows convention that the upper 16 bits of an
44 * 'unsigned short' result are still zero. This macro doesn't
45 * follow convention; indeed, it leaves garbage in the upport 16
46 * bits of the register.
47
48 * Declaring the temporary variables 'res' and 'tmp' to be 32-bit
49 * types while the return type of the function is a 16-bit type
50 * forces both compilers to insert exactly one extui instruction
51 * (or equivalent) to mask off the upper 16 bits. */
52
53 __u32 res;
54 __u32 tmp;
55
56 __asm__("extui %1, %2, 8, 8\n\t"
57 "slli %0, %2, 8 \n\t"
58 "or %0, %0, %1 \n"
59 : "=&a" (res), "=&a" (tmp)
60 : "a" (x)
61 );
62
63 return res;
64}
65
66#define __arch__swab32(x) ___arch__swab32(x)
67#define __arch__swab16(x) ___arch__swab16(x)
68
69#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
70# define __BYTEORDER_HAS_U64__
71# define __SWAB_64_THRU_32__
72#endif
73
74#ifdef __XTENSA_EL__
75# include <linux/byteorder/little_endian.h>
76#elif defined(__XTENSA_EB__)
77# include <linux/byteorder/big_endian.h>
78#else
79# error processor byte order undefined!
80#endif
81
82#endif /* __ASM_XTENSA_BYTEORDER_H */