1/* 2 * linux/arch/alpha/lib/memcpy.c 3 * 4 * Copyright (C) 1995 Linus Torvalds 5 */ 6 7/* 8 * This is a reasonably optimized memcpy() routine. 9 */ 10 11/* 12 * Note that the C code is written to be optimized into good assembly. However, 13 * at this point gcc is unable to sanely compile "if (n >= 0)", resulting in a 14 * explicit compare against 0 (instead of just using the proper "blt reg, xx" or 15 * "bge reg, xx"). I hope alpha-gcc will be fixed to notice this eventually.. 16 */ 17 18#include <linux/types.h> 19 20/* 21 * This should be done in one go with ldq_u*2/mask/stq_u. Do it 22 * with a macro so that we can fix it up later.. 23 */ 24#define ALIGN_DEST_TO8_UP(d,s,n) \ 25 while (d & 7) { \ 26 if (n <= 0) return; \ 27 n--; \ 28 *(char *) d = *(char *) s; \ 29 d++; s++; \ 30 } 31#define ALIGN_DEST_TO8_DN(d,s,n) \ 32 while (d & 7) { \ 33 if (n <= 0) return; \ 34 n--; \ 35 d--; s--; \ 36 *(char *) d = *(char *) s; \ 37 } 38 39/* 40 * This should similarly be done with ldq_u*2/mask/stq. The destination 41 * is aligned, but we don't fill in a full quad-word 42 */ 43#define DO_REST_UP(d,s,n) \ 44 while (n > 0) { \ 45 n--; \ 46 *(char *) d = *(char *) s; \ 47 d++; s++; \ 48 } 49#define DO_REST_DN(d,s,n) \ 50 while (n > 0) { \ 51 n--; \ 52 d--; s--; \ 53 *(char *) d = *(char *) s; \ 54 } 55 56/* 57 * This should be done with ldq/mask/stq. The source and destination are 58 * aligned, but we don't fill in a full quad-word 59 */ 60#define DO_REST_ALIGNED_UP(d,s,n) DO_REST_UP(d,s,n) 61#define DO_REST_ALIGNED_DN(d,s,n) DO_REST_DN(d,s,n) 62 63/* 64 * This does unaligned memory copies. We want to avoid storing to 65 * an unaligned address, as that would do a read-modify-write cycle. 66 * We also want to avoid double-reading the unaligned reads. 67 * 68 * Note the ordering to try to avoid load (and address generation) latencies. 69 */ 70static inline void __memcpy_unaligned_up (unsigned long d, unsigned long s, 71 long n) 72{ 73 ALIGN_DEST_TO8_UP(d,s,n); 74 n -= 8; /* to avoid compare against 8 in the loop */ 75 if (n >= 0) { 76 unsigned long low_word, high_word; 77 __asm__("ldq_u %0,%1":"=r" (low_word):"m" (*(unsigned long *) s)); 78 do { 79 unsigned long tmp; 80 __asm__("ldq_u %0,%1":"=r" (high_word):"m" (*(unsigned long *)(s+8))); 81 n -= 8; 82 __asm__("extql %1,%2,%0" 83 :"=r" (low_word) 84 :"r" (low_word), "r" (s)); 85 __asm__("extqh %1,%2,%0" 86 :"=r" (tmp) 87 :"r" (high_word), "r" (s)); 88 s += 8; 89 *(unsigned long *) d = low_word | tmp; 90 d += 8; 91 low_word = high_word; 92 } while (n >= 0); 93 } 94 n += 8; 95 DO_REST_UP(d,s,n); 96} 97 98static inline void __memcpy_unaligned_dn (unsigned long d, unsigned long s, 99 long n) 100{ 101 /* I don't understand AXP assembler well enough for this. -Tim */ 102 s += n; 103 d += n; 104 while (n--) 105 * (char *) --d = * (char *) --s; 106} 107 108/* 109 * Hmm.. Strange. The __asm__ here is there to make gcc use an integer register 110 * for the load-store. I don't know why, but it would seem that using a floating 111 * point register for the move seems to slow things down (very small difference, 112 * though). 113 * 114 * Note the ordering to try to avoid load (and address generation) latencies. 115 */ 116static inline void __memcpy_aligned_up (unsigned long d, unsigned long s, 117 long n) 118{ 119 ALIGN_DEST_TO8_UP(d,s,n); 120 n -= 8; 121 while (n >= 0) { 122 unsigned long tmp; 123 __asm__("ldq %0,%1":"=r" (tmp):"m" (*(unsigned long *) s)); 124 n -= 8; 125 s += 8; 126 *(unsigned long *) d = tmp; 127 d += 8; 128 } 129 n += 8; 130 DO_REST_ALIGNED_UP(d,s,n); 131} 132static inline void __memcpy_aligned_dn (unsigned long d, unsigned long s, 133 long n) 134{ 135 s += n; 136 d += n; 137 ALIGN_DEST_TO8_DN(d,s,n); 138 n -= 8; 139 while (n >= 0) { 140 unsigned long tmp; 141 s -= 8; 142 __asm__("ldq %0,%1":"=r" (tmp):"m" (*(unsigned long *) s)); 143 n -= 8; 144 d -= 8; 145 *(unsigned long *) d = tmp; 146 } 147 n += 8; 148 DO_REST_ALIGNED_DN(d,s,n); 149} 150 151void * memcpy(void * dest, const void *src, size_t n) 152{ 153 if (!(((unsigned long) dest ^ (unsigned long) src) & 7)) { 154 __memcpy_aligned_up ((unsigned long) dest, (unsigned long) src, 155 n); 156 return dest; 157 } 158 __memcpy_unaligned_up ((unsigned long) dest, (unsigned long) src, n); 159 return dest; 160} 161 162/* For backward modules compatibility, define __memcpy. */ 163asm("__memcpy = memcpy; .globl __memcpy"); 164