Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/mips/mips/bcopy.S
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1 /* $NetBSD: bcopy.S,v 1.3 2009/12/14 00:39:00 matt Exp $ */ 2 3 /* 4 * Mach Operating System 5 * Copyright (c) 1993 Carnegie Mellon University 6 * All Rights Reserved. 7 * 8 * Permission to use, copy, modify and distribute this software and its 9 * documentation is hereby granted, provided that both the copyright 10 * notice and this permission notice appear in all copies of the 11 * software, derivative works or modified versions, and any portions 12 * thereof, and that both notices appear in supporting documentation. 13 * 14 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 15 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 16 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 17 * 18 * Carnegie Mellon requests users of this software to return to 19 * 20 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 21 * School of Computer Science 22 * Carnegie Mellon University 23 * Pittsburgh PA 15213-3890 24 * 25 * any improvements or extensions that they make and grant Carnegie Mellon 26 * the rights to redistribute these changes. 27 */ 28 29 /* 30 * File: mips_bcopy.s 31 * Author: Chris Maeda 32 * Date: June 1993 33 * 34 * Fast copy routine. Derived from aligned_block_copy. 35 */ 36 37 38 #include <machine/asm.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <machine/endian.h> 42 43 #if defined(LIBC_SCCS) && !defined(lint) 44 #if 0 45 ASMSTR("from: @(#)mips_bcopy.s 2.2 CMU 18/06/93") 46 #else 47 ASMSTR("$NetBSD: bcopy.S,v 1.3 2009/12/14 00:39:00 matt Exp $") 48 #endif 49 #endif /* LIBC_SCCS and not lint */ 50 51 #ifdef __ABICALLS__ 52 .abicalls 53 #endif 54 55 /* 56 * bcopy(caddr_t src, caddr_t dst, unsigned int len) 57 * 58 * a0 src address 59 * a1 dst address 60 * a2 length 61 */ 62 63 #define SRCREG a0 64 #define DSTREG a1 65 #define SIZEREG a2 66 67 LEAF(memcpy) 68 XLEAF(memmove) 69 .set noat 70 .set noreorder 71 72 move v0, a0 73 move a0, a1 74 move a1, v0 75 76 XLEAF(bcopy) 77 XLEAF(ovbcopy) 78 /* 79 * Make sure we can copy forwards. 80 */ 81 sltu t0,SRCREG,DSTREG # t0 == SRCREG < DSTREG 82 bne t0,zero,6f # copy backwards 83 84 /* 85 * There are four alignment cases (with frequency) 86 * (Based on measurements taken with a DECstation 5000/200 87 * inside a Mach kernel.) 88 * 89 * aligned -> aligned (mostly) 90 * unaligned -> aligned (sometimes) 91 * aligned,unaligned -> unaligned (almost never) 92 * 93 * Note that we could add another case that checks if 94 * the destination and source are unaligned but the 95 * copy is alignable. eg if src and dest are both 96 * on a halfword boundary. 97 */ 98 andi t1,DSTREG,(SZREG-1) # get last bits of dest 99 bne t1,zero,3f # dest unaligned 100 andi t0,SRCREG,(SZREG-1) # get last bits of src 101 bne t0,zero,5f 102 103 /* 104 * Forward aligned->aligned copy, 8 words at a time. 105 */ 106 98: 107 li AT,-(SZREG*8) 108 and t0,SIZEREG,AT # count truncated to multiples 109 PTR_ADDU a3,SRCREG,t0 # run fast loop up to this addr 110 sltu AT,SRCREG,a3 # any work to do? 111 beq AT,zero,2f 112 PTR_SUBU SIZEREG,t0 113 114 /* 115 * loop body 116 */ 117 1: # cp 118 REG_L t3,(0*SZREG)(SRCREG) 119 REG_L v1,(1*SZREG)(SRCREG) 120 REG_L t0,(2*SZREG)(SRCREG) 121 REG_L t1,(3*SZREG)(SRCREG) 122 PTR_ADDU SRCREG,SZREG*8 123 REG_S t3,(0*SZREG)(DSTREG) 124 REG_S v1,(1*SZREG)(DSTREG) 125 REG_S t0,(2*SZREG)(DSTREG) 126 REG_S t1,(3*SZREG)(DSTREG) 127 REG_L t1,(-1*SZREG)(SRCREG) 128 REG_L t0,(-2*SZREG)(SRCREG) 129 REG_L v1,(-3*SZREG)(SRCREG) 130 REG_L t3,(-4*SZREG)(SRCREG) 131 PTR_ADDU DSTREG,SZREG*8 132 REG_S t1,(-1*SZREG)(DSTREG) 133 REG_S t0,(-2*SZREG)(DSTREG) 134 REG_S v1,(-3*SZREG)(DSTREG) 135 bne SRCREG,a3,1b 136 REG_S t3,(-4*SZREG)(DSTREG) 137 138 /* 139 * Copy a word at a time, no loop unrolling. 140 */ 141 2: # wordcopy 142 andi t2,SIZEREG,(SZREG-1) # get byte count / SZREG 143 PTR_SUBU t2,SIZEREG,t2 # t2 = words to copy * SZREG 144 beq t2,zero,3f 145 PTR_ADDU t0,SRCREG,t2 # stop at t0 146 PTR_SUBU SIZEREG,SIZEREG,t2 147 1: 148 REG_L t3,0(SRCREG) 149 PTR_ADDU SRCREG,SZREG 150 REG_S t3,0(DSTREG) 151 bne SRCREG,t0,1b 152 PTR_ADDU DSTREG,SZREG 153 154 3: # bytecopy 155 beq SIZEREG,zero,4f # nothing left to do? 156 nop 157 1: 158 lb t3,0(SRCREG) 159 PTR_ADDU SRCREG,1 160 sb t3,0(DSTREG) 161 PTR_SUBU SIZEREG,1 162 bgtz SIZEREG,1b 163 PTR_ADDU DSTREG,1 164 165 4: # copydone 166 j ra 167 nop 168 169 /* 170 * Copy from unaligned source to aligned dest. 171 */ 172 5: # destaligned 173 andi t0,SIZEREG,(SZREG-1) # t0 = bytecount mod SZREG 174 PTR_SUBU a3,SIZEREG,t0 # number of words to transfer 175 beq a3,zero,3b 176 nop 177 move SIZEREG,t0 # this many to do after we are done 178 PTR_ADDU a3,SRCREG,a3 # stop point 179 180 1: 181 REG_LHI t3,0(SRCREG) 182 REG_LLO t3,SZREG-1(SRCREG) 183 PTR_ADDI SRCREG,SZREG 184 REG_S t3,0(DSTREG) 185 bne SRCREG,a3,1b 186 PTR_ADDI DSTREG,SZREG 187 188 b 3b 189 nop 190 191 6: # backcopy -- based on above 192 PTR_ADDU SRCREG,SIZEREG 193 PTR_ADDU DSTREG,SIZEREG 194 andi t1,DSTREG,SZREG-1 # get last 3 bits of dest 195 bne t1,zero,3f 196 andi t0,SRCREG,SZREG-1 # get last 3 bits of src 197 bne t0,zero,5f 198 199 /* 200 * Forward aligned->aligned copy, 8*4 bytes at a time. 201 */ 202 li AT,(-8*SZREG) 203 and t0,SIZEREG,AT # count truncated to multiple of 32 204 beq t0,zero,2f # any work to do? 205 PTR_SUBU SIZEREG,t0 206 PTR_SUBU a3,SRCREG,t0 207 208 /* 209 * loop body 210 */ 211 1: # cp 212 REG_L t3,(-4*SZREG)(SRCREG) 213 REG_L v1,(-3*SZREG)(SRCREG) 214 REG_L t0,(-2*SZREG)(SRCREG) 215 REG_L t1,(-1*SZREG)(SRCREG) 216 PTR_SUBU SRCREG,8*SZREG 217 REG_S t3,(-4*SZREG)(DSTREG) 218 REG_S v1,(-3*SZREG)(DSTREG) 219 REG_S t0,(-2*SZREG)(DSTREG) 220 REG_S t1,(-1*SZREG)(DSTREG) 221 REG_L t1,(3*SZREG)(SRCREG) 222 REG_L t0,(2*SZREG)(SRCREG) 223 REG_L v1,(1*SZREG)(SRCREG) 224 REG_L t3,(0*SZREG)(SRCREG) 225 PTR_SUBU DSTREG,8*SZREG 226 REG_S t1,(3*SZREG)(DSTREG) 227 REG_S t0,(2*SZREG)(DSTREG) 228 REG_S v1,(1*SZREG)(DSTREG) 229 bne SRCREG,a3,1b 230 REG_S t3,(0*SZREG)(DSTREG) 231 232 /* 233 * Copy a word at a time, no loop unrolling. 234 */ 235 2: # wordcopy 236 andi t2,SIZEREG,SZREG-1 # get byte count / 4 237 PTR_SUBU t2,SIZEREG,t2 # t2 = number of words to copy 238 beq t2,zero,3f 239 PTR_SUBU t0,SRCREG,t2 # stop at t0 240 PTR_SUBU SIZEREG,SIZEREG,t2 241 1: 242 REG_L t3,-SZREG(SRCREG) 243 PTR_SUBU SRCREG,SZREG 244 REG_S t3,-SZREG(DSTREG) 245 bne SRCREG,t0,1b 246 PTR_SUBU DSTREG,SZREG 247 248 3: # bytecopy 249 beq SIZEREG,zero,4f # nothing left to do? 250 nop 251 1: 252 lb t3,-1(SRCREG) 253 PTR_SUBU SRCREG,1 254 sb t3,-1(DSTREG) 255 PTR_SUBU SIZEREG,1 256 bgtz SIZEREG,1b 257 PTR_SUBU DSTREG,1 258 259 4: # copydone 260 j ra 261 nop 262 263 /* 264 * Copy from unaligned source to aligned dest. 265 */ 266 5: # destaligned 267 andi t0,SIZEREG,SZREG-1 # t0 = bytecount mod 4 268 PTR_SUBU a3,SIZEREG,t0 # number of words to transfer 269 beq a3,zero,3b 270 nop 271 move SIZEREG,t0 # this many to do after we are done 272 PTR_SUBU a3,SRCREG,a3 # stop point 273 274 1: 275 REG_LHI t3,-SZREG(SRCREG) 276 REG_LLO t3,-1(SRCREG) 277 PTR_SUBU SRCREG,SZREG 278 REG_S t3,-SZREG(DSTREG) 279 bne SRCREG,a3,1b 280 PTR_SUBU DSTREG,SZREG 281 282 b 3b 283 nop 284 285 .set reorder 286 .set at 287 END(memcpy)
Cache object: 33bead2dde72ffeded96ecb40fd91ef4
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