1/* 2 * include/asm-v850/unaligned.h -- Unaligned memory access 3 * 4 * Copyright (C) 2001 NEC Corporation 5 * Copyright (C) 2001 Miles Bader <miles@gnu.org> 6 * 7 * This file is subject to the terms and conditions of the GNU General 8 * Public License. See the file COPYING in the main directory of this 9 * archive for more details. 10 * 11 * This file is a copy of the arm version, include/asm-arm/unaligned.h 12 * 13 * Note that some v850 chips support unaligned access, but it seems too 14 * annoying to use. 15 */ 16 17#ifndef __V850_UNALIGNED_H__ 18#define __V850_UNALIGNED_H__ 19 20#include <asm/types.h> 21 22extern int __bug_unaligned_x(void *ptr); 23 24/* 25 * What is the most efficient way of loading/storing an unaligned value? 26 * 27 * That is the subject of this file. Efficiency here is defined as 28 * minimum code size with minimum register usage for the common cases. 29 * It is currently not believed that long longs are common, so we 30 * trade efficiency for the chars, shorts and longs against the long 31 * longs. 32 * 33 * Current stats with gcc 2.7.2.2 for these functions: 34 * 35 * ptrsize get: code regs put: code regs 36 * 1 1 1 1 2 37 * 2 3 2 3 2 38 * 4 7 3 7 3 39 * 8 20 6 16 6 40 * 41 * gcc 2.95.1 seems to code differently: 42 * 43 * ptrsize get: code regs put: code regs 44 * 1 1 1 1 2 45 * 2 3 2 3 2 46 * 4 7 4 7 4 47 * 8 19 8 15 6 48 * 49 * which may or may not be more efficient (depending upon whether 50 * you can afford the extra registers). Hopefully the gcc 2.95 51 * is inteligent enough to decide if it is better to use the 52 * extra register, but evidence so far seems to suggest otherwise. 53 * 54 * Unfortunately, gcc is not able to optimise the high word 55 * out of long long >> 32, or the low word from long long << 32 56 */ 57 58#define __get_unaligned_2(__p) \ 59 (__p[0] | __p[1] << 8) 60 61#define __get_unaligned_4(__p) \ 62 (__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24) 63 64#define get_unaligned(ptr) \ 65 ({ \ 66 __typeof__(*(ptr)) __v; \ 67 __u8 *__p = (__u8 *)(ptr); \ 68 switch (sizeof(*(ptr))) { \ 69 case 1: __v = *(ptr); break; \ 70 case 2: __v = __get_unaligned_2(__p); break; \ 71 case 4: __v = __get_unaligned_4(__p); break; \ 72 case 8: { \ 73 unsigned int __v1, __v2; \ 74 __v2 = __get_unaligned_4((__p+4)); \ 75 __v1 = __get_unaligned_4(__p); \ 76 __v = ((unsigned long long)__v2 << 32 | __v1); \ 77 } \ 78 break; \ 79 default: __v = __bug_unaligned_x(__p); break; \ 80 } \ 81 __v; \ 82 }) 83 84 85static inline void __put_unaligned_2(__u32 __v, register __u8 *__p) 86{ 87 *__p++ = __v; 88 *__p++ = __v >> 8; 89} 90 91static inline void __put_unaligned_4(__u32 __v, register __u8 *__p) 92{ 93 __put_unaligned_2(__v >> 16, __p + 2); 94 __put_unaligned_2(__v, __p); 95} 96 97static inline void __put_unaligned_8(const unsigned long long __v, register __u8 *__p) 98{ 99 /* 100 * tradeoff: 8 bytes of stack for all unaligned puts (2 101 * instructions), or an extra register in the long long 102 * case - go for the extra register. 103 */ 104 __put_unaligned_4(__v >> 32, __p+4); 105 __put_unaligned_4(__v, __p); 106} 107 108/* 109 * Try to store an unaligned value as efficiently as possible. 110 */ 111#define put_unaligned(val,ptr) \ 112 ({ \ 113 switch (sizeof(*(ptr))) { \ 114 case 1: \ 115 *(ptr) = (val); \ 116 break; \ 117 case 2: __put_unaligned_2((val),(__u8 *)(ptr)); \ 118 break; \ 119 case 4: __put_unaligned_4((val),(__u8 *)(ptr)); \ 120 break; \ 121 case 8: __put_unaligned_8((val),(__u8 *)(ptr)); \ 122 break; \ 123 default: __bug_unaligned_x(ptr); \ 124 break; \ 125 } \ 126 (void) 0; \ 127 }) 128 129 130#endif /* __V850_UNALIGNED_H__ */ 131