1/******************************************************************************* 2 * 3 * Copyright (c) 1993 Intel Corporation 4 * 5 * Intel hereby grants you permission to copy, modify, and distribute this 6 * software and its documentation. Intel grants this permission provided 7 * that the above copyright notice appears in all copies and that both the 8 * copyright notice and this permission notice appear in supporting 9 * documentation. In addition, Intel grants this permission provided that 10 * you prominently mark as "not part of the original" any modifications 11 * made to this software or documentation, and that the name of Intel 12 * Corporation not be used in advertising or publicity pertaining to 13 * distribution of the software or the documentation without specific, 14 * written prior permission. 15 * 16 * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR 17 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY 18 * OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or 19 * representations regarding the use of, or the results of the use of, 20 * the software and documentation in terms of correctness, accuracy, 21 * reliability, currentness, or otherwise; and you rely on the software, 22 * documentation and results solely at your own risk. 23 * 24 * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS, 25 * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES 26 * OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM 27 * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER. 28 * 29 ******************************************************************************/ 30 31 .file "sncpy_ca.s" 32#ifdef __PIC 33 .pic 34#endif 35#ifdef __PID 36 .pid 37#endif 38/* 39 * (c) copyright 1988,1993 Intel Corp., all rights reserved 40 */ 41 42/* 43 procedure strncpy (optimized assembler version for the CA) 44 45 dest_addr = strncpy (dest_addr, src_addr, max_bytes) 46 47 copy the null terminated string pointed to by src_addr to 48 the string space pointed to by dest_addr. Return the original 49 dest_addr. If the source string is shorter than max_bytes, 50 then null-pad the destination string. 51 52 This routine will fail if the source and destination string 53 overlap (in particular, if the end of the source is overlapped 54 by the beginning of the destination). The behavior is undefined. 55 This is acceptable according to the draft C standard. 56 57 Undefined behavior will also occur if the end of the source string 58 (i.e. the terminating null byte) is in the last word of the program's 59 allocated memory space. This is so because, in several cases, strcpy 60 will fetch ahead one word. Disallowing the fetch ahead would impose 61 a severe performance penalty. 62 63 This program handles five cases: 64 65 1) both arguments start on a word boundary 66 2) neither are word aligned, but they are offset by the same amount 67 3) source is word aligned, destination is not 68 4) destination is word aligned, source is not 69 5) neither is word aligned, and they are offset by differing amounts 70 71 At the time of this writing, only g0 thru g7 and g13 are available 72 for use in this leafproc; other registers would have to be saved and 73 restored. These nine registers, plus tricky use of g14 are sufficient 74 to implement the routine. The registers are used as follows: 75 76 g0 original dest ptr; not modified, so that it may be returned. 77 g1 src ptr; shift count 78 g2 max_bytes 79 g3 src ptr (word aligned) 80 g4 dest ptr (word aligned) 81 g5 0xff -- byte extraction mask 82 Little endian: 83 g6 lsw of double word for extraction of 4 bytes 84 g7 msw of double word for extraction of 4 bytes 85 Big endian: 86 g6 msw of double word for extraction of 4 bytes 87 g7 lsw of double word for extraction of 4 bytes 88 g13 return address 89 g14 byte extracted. 90*/ 91 92#if __i960_BIG_ENDIAN__ 93#define MSW g6 94#define LSW g7 95#else 96#define LSW g6 97#define MSW g7 98#endif 99 100 .globl _strncpy 101 .globl __strncpy 102 .leafproc _strncpy, __strncpy 103 .align 2 104_strncpy: 105#ifndef __PIC 106 lda Lrett,g14 107#else 108 lda Lrett-(.+8)(ip),g14 109#endif 110__strncpy: 111 notand g1,3,g3 # extract word addr of start of src 112 lda (g14),g13 # preserve return address 113 cmpibge.f 0,g2,Lexit_code # Lexit if number of bytes to move is <= zero. 114 cmpo g3,g1 # check alignment of src 115 ld (g3),LSW # fetch word containing at least first byte 116 notand g0,3,g4 # extract word addr of start of dest 117 lda 4(g3),g3 # advance src word addr 118 bne.f Lcase_245 # branch if src is NOT word aligned 119 120Lcase_13: 121 cmpo g0,g4 # check alignment of dest 122 lda 0xff,g5 # load mask for byte extraction 123 subo 4,g4,g4 # store is pre-incrementing; back up dest addr 124 bne.f Lcase_3 # branch if dest not word aligned 125 126Lcase_1: # src and dest are word aligned 127Lcase_1_wloop: # word copying loop 128 cmpi g2,4 # check for fewer than four bytes to move 129 lda (LSW),g1 # keep a copy of the src word 130 addo 4,g4,g4 # pre-increment dest addr 131 bl.f Lcase_1_cloop.a # branch if fewer than four bytes to copy 132 scanbyte 0,g1 # check for null byte in src word 133 ld (g3),LSW # pre-fetch next word of src 134 subi 4,g2,g2 # decrease max_byte count by the 4 bytes moved 135 bo.f Lcase_1_cloop.c # branch if word contains null byte 136 addo 4,g3,g3 # post-increment src addr 137 st g1,(g4) # store word in dest string 138 b Lcase_1_wloop 139 140Lcase_3_cloop.a: 141Lcase_1_cloop.a: # character copying loop (max_bytes <= 3) 142#if __i960_BIG_ENDIAN__ 143 rotate 8,g1,g1 # move next byte into position for extraction 144#endif 145 and g5,g1,g14 # extract next char 146Lcase_1_cloop.b: 147 cmpdeci 0,g2,g2 # is max_bytes exhausted? 148 be.f Lexit_code # Lexit if max_bytes is exhausted 149 cmpo 0,g14 # check for null byte 150 stob g14,(g4) # store the byte in dest 151#if ! __i960_BIG_ENDIAN__ 152 shro 8,g1,g1 # move next byte into position for extraction 153#endif 154 lda 1(g4),g4 # post-increment dest byte addr 155 bne.t Lcase_1_cloop.a # branch if null not reached 156 b Lcase_1_cloop.b 157 158Lexit_code: 159 mov 0,g14 # conform to register conventions 160 bx (g13) # g0 = addr of dest; g14 = 0 161Lrett: 162 ret 163 164Lcase_1_cloop.c: 165Lcase_3_cloop.c: 166#if __i960_BIG_ENDIAN__ 167 rotate 24,g5,g5 # move mask into position for testing next byte 168#endif 169 and g5,g1,g14 # extract next char 170 cmpo 0,g14 # check for null byte 171#if ! __i960_BIG_ENDIAN__ 172 lda (g5),LSW # keep a copy of the current mask 173 shlo 8,g5,g5 # move mask into position for testing next byte 174#endif 175 bne.t Lcase_1_cloop.c # branch if null not reached 176#if __i960_BIG_ENDIAN__ 177 subo 1,g5,g5 # null pad. 178 andnot g5,g1,g1 # last bytes to copy, and null pad rest of word 179#else 180 subo 1,LSW,g5 # mask to get last bytes to copy, and null pad 181 and g5,g1,g1 # last bytes to copy, and null pad rest of word 182#endif 183 st g1,(g4) 184 185Lcase_1_zwloop: # zero word loop 186 cmpi g2,4 # check for fewer than four bytes to move 187 addo 4,g4,g4 # pre-increment dest addr 188 bl.f Lcase_1_cloop.b # branch if fewer than four bytes to copy 189 subo 4,g2,g2 # decrease max_byte count by the 4 bytes moved 190 st g14,(g4) # store word in dest string 191 b Lcase_1_zwloop 192 193Lcase_3: # src is word aligned; dest is not 194 addo 8,g4,g4 # move dest word ptr to first word boundary 195 lda (g0),g1 # copy dest byte ptr 196 mov LSW,MSW # make copy of first word of src 197 lda 32,g14 # initialize shift count to zero (mod 32) 198 199Lcase_25: 200Lcase_3_cloop_at_start: # character copying loop for start of dest str 201 cmpdeci 0,g2,g2 # is max_bytes exhausted? 202#if __i960_BIG_ENDIAN__ 203 shro 24,MSW,g5 # extract next char 204#else 205 and g5,MSW,g5 # extract next char 206#endif 207 be.f Lexit_code # Lexit if max_bytes is exhausted 208 cmpo 0,g5 # check for null byte 209 stob g5,(g1) # store the byte in dest 210 addo 1,g1,g1 # post-increment dest ptr 211 lda 0xff,g5 # re-initialize byte extraction mask 212 bne.t 1f # drop thru if null byte reached (to pad) 213 movl 0,g6 # blank out remainder of input buffer 2141: 215 cmpo g1,g4 # have we reached word boundary in dest yet? 216#if __i960_BIG_ENDIAN__ 217 lda -8(g14),g14 # augment the shift counter 218 rotate 8,MSW,MSW # move next byte into position for extraction 219#else 220 lda 8(g14),g14 # augment the shift counter 221 shro 8,MSW,MSW # move next byte into position for extraction 222#endif 223 bne.t Lcase_3_cloop_at_start # branch if reached word boundary? 224 225 ld (g3),MSW # fetch msw of operand for double shift 226 227Lcase_4: 228 229#if __i960_BIG_ENDIAN__ 230 cmpobne 0,g14,Lcase_3_wloop # branch if src is still unaligned. 231 232Lcase_3_wloop2: 233 cmpi g2,4 # less than four bytes to move? 234 lda (LSW),g1 # extract 4 bytes of src 235 lda 4(g3),g3 # post-increment src word addr 236 bl.f Lcase_3_cloop.a # branch if < four bytes left to move 237 scanbyte 0,g1 # check for null byte 238 lda (MSW),LSW # move msw to lsw 239 subi 4,g2,g2 # decrease max_byte count by the 4 bytes moved 240 ld (g3),MSW # pre-fetch msw of operand for double shift 241 bo.f Lcase_3_cloop.c # branch if word contains null byte 242 st g1,(g4) # store 4 bytes to dest 243 addo 4,g4,g4 # post-increment dest ptr 244 b Lcase_3_wloop2 245 246#endif 247 248Lcase_3_wloop: 249 cmpi g2,4 # less than four bytes to move? 250 eshro g14,g6,g1 # extract 4 bytes of src 251 lda 4(g3),g3 # post-increment src word addr 252 bl.f Lcase_3_cloop.a # branch if < four bytes left to move 253 scanbyte 0,g1 # check for null byte 254 lda (MSW),LSW # move msw to lsw 255 subi 4,g2,g2 # decrease max_byte count by the 4 bytes moved 256 ld (g3),MSW # pre-fetch msw of operand for double shift 257 bo.f Lcase_3_cloop.c # branch if word contains null byte 258 st g1,(g4) # store 4 bytes to dest 259 addo 4,g4,g4 # post-increment dest ptr 260 b Lcase_3_wloop 261 262Lcase_245: 263 cmpo g0,g4 # check alignment of dest 264 ld (g3),MSW # pre-fetch second half 265 and 3,g1,g1 # compute shift count 266 lda 0xff,g5 # load mask for byte extraction 267#if __i960_BIG_ENDIAN__ 268 subo g1,4,g14 # adjust shift count for big endian. 269 shlo 3,g14,g14 270#else 271 shlo 3,g1,g14 272#endif 273 be.t Lcase_4 # branch if dest is word aligned 274 or g4,g1,g1 # is src earlier in word, later, or sync w/ dst 275 cmpo g0,g1 # < indicates first word of dest has more bytes 276 /* than first word of source. */ 277 lda 4(g4),g4 # move dest word addr to first word boundary 278 eshro g14,g6,g5 # extract four bytes 279 lda (g0),g1 280 bg.f 1f 281 mov MSW,LSW 282 lda 4(g3),g3 # move src word addr to second word boundary 2831: 284 mov g5,MSW 285 lda 0xff,g5 286 b Lcase_25 287 288/* end of strncpy */ 289 290
