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/arch/blackfin/lib/memcpy.S

https://bitbucket.org/thekraven/iscream_thunderc-2.6.35
Assembly | 124 lines | 110 code | 14 blank | 0 comment | 3 complexity | ce5e5b8eaf1b4f2f5689846baf7d1ba0 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/*
  2 * internal version of memcpy(), issued by the compiler to copy blocks of
  3 * data around. This is really memmove() - it has to be able to deal with
  4 * possible overlaps, because that ambiguity is when the compiler gives up
  5 * and calls a function. We have our own, internal version so that we get
  6 * something we trust, even if the user has redefined the normal symbol.
  7 *
  8 * Copyright 2004-2009 Analog Devices Inc.
  9 *
 10 * Licensed under the ADI BSD license or the GPL-2 (or later)
 11 */
 12
 13#include <linux/linkage.h>
 14
 15/* void *memcpy(void *dest, const void *src, size_t n);
 16 * R0 = To Address (dest) (leave unchanged to form result)
 17 * R1 = From Address (src)
 18 * R2 = count
 19 *
 20 * Note: Favours word alignment
 21 */
 22
 23#ifdef CONFIG_MEMCPY_L1
 24.section .l1.text
 25#else
 26.text
 27#endif
 28
 29.align 2
 30
 31ENTRY(_memcpy)
 32	CC = R2 <=  0;	/* length not positive? */
 33	IF CC JUMP .L_P1L2147483647;	/* Nothing to do */
 34
 35	P0 = R0 ;	/* dst*/
 36	P1 = R1 ;	/* src*/
 37	P2 = R2 ;	/* length */
 38
 39	/* check for overlapping data */
 40	CC = R1 < R0;	/* src < dst */
 41	IF !CC JUMP .Lno_overlap;
 42	R3 = R1 + R2;
 43	CC = R0 < R3;	/* and dst < src+len */
 44	IF CC JUMP .Lhas_overlap;
 45
 46.Lno_overlap:
 47	/* Check for aligned data.*/
 48
 49	R3 = R1 | R0;
 50	R1 = 0x3;
 51	R3 = R3 & R1;
 52	CC = R3;	/* low bits set on either address? */
 53	IF CC JUMP .Lnot_aligned;
 54
 55	/* Both addresses are word-aligned, so we can copy
 56	at least part of the data using word copies.*/
 57	P2 = P2 >> 2;
 58	CC = P2 <= 2;
 59	IF !CC JUMP .Lmore_than_seven;
 60	/* less than eight bytes... */
 61	P2 = R2;
 62	LSETUP(.Lthree_start, .Lthree_end) LC0=P2;
 63.Lthree_start:
 64	R3 = B[P1++] (X);
 65.Lthree_end:
 66	B[P0++] = R3;
 67
 68	RTS;
 69
 70.Lmore_than_seven:
 71	/* There's at least eight bytes to copy. */
 72	P2 += -1;	/* because we unroll one iteration */
 73	LSETUP(.Lword_loops, .Lword_loope) LC0=P2;
 74	I1 = P1;
 75	R3 = [I1++];
 76#if ANOMALY_05000202
 77.Lword_loops:
 78	[P0++] = R3;
 79.Lword_loope:
 80	R3 = [I1++];
 81#else
 82.Lword_loops:
 83.Lword_loope:
 84	MNOP || [P0++] = R3 || R3 = [I1++];
 85#endif
 86	[P0++] = R3;
 87	/* Any remaining bytes to copy? */
 88	R3 = 0x3;
 89	R3 = R2 & R3;
 90	CC = R3 == 0;
 91	P1 = I1;	/* in case there's something left, */
 92	IF !CC JUMP .Lbytes_left;
 93	RTS;
 94.Lbytes_left:	P2 = R3;
 95.Lnot_aligned:
 96	/* From here, we're copying byte-by-byte. */
 97	LSETUP (.Lbyte_start, .Lbyte_end) LC0=P2;
 98.Lbyte_start:
 99	R1 = B[P1++] (X);
100.Lbyte_end:
101	B[P0++] = R1;
102
103.L_P1L2147483647:
104	RTS;
105
106.Lhas_overlap:
107	/* Need to reverse the copying, because the
108	 * dst would clobber the src.
109	 * Don't bother to work out alignment for
110	 * the reverse case.
111	 */
112	P0 = P0 + P2;
113	P0 += -1;
114	P1 = P1 + P2;
115	P1 += -1;
116	LSETUP(.Lover_start, .Lover_end) LC0=P2;
117.Lover_start:
118	R1 = B[P1--] (X);
119.Lover_end:
120	B[P0--] = R1;
121
122	RTS;
123
124ENDPROC(_memcpy)