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Diffstat (limited to 'newlib/libc/machine/i960/strncpy.S')
| -rw-r--r-- | newlib/libc/machine/i960/strncpy.S | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strncpy.S b/newlib/libc/machine/i960/strncpy.S new file mode 100644 index 00000000000..9f51b607c94 --- /dev/null +++ b/newlib/libc/machine/i960/strncpy.S @@ -0,0 +1,154 @@ +/******************************************************************************* + * + * Copyright (c) 1993 Intel Corporation + * + * Intel hereby grants you permission to copy, modify, and distribute this + * software and its documentation. Intel grants this permission provided + * that the above copyright notice appears in all copies and that both the + * copyright notice and this permission notice appear in supporting + * documentation. In addition, Intel grants this permission provided that + * you prominently mark as "not part of the original" any modifications + * made to this software or documentation, and that the name of Intel + * Corporation not be used in advertising or publicity pertaining to + * distribution of the software or the documentation without specific, + * written prior permission. + * + * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR + * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY + * OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or + * representations regarding the use of, or the results of the use of, + * the software and documentation in terms of correctness, accuracy, + * reliability, currentness, or otherwise; and you rely on the software, + * documentation and results solely at your own risk. + * + * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS, + * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES + * OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM + * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER. + * + ******************************************************************************/ + + .file "strncpy.s" +#ifdef __PIC + .pic +#endif +#ifdef __PID + .pid +#endif +/* + * (c) copyright 1988,1993 Intel Corp., all rights reserved + */ +/* + procedure strncpy (optimized assembler version for the 80960K Series) + + dest_addr = strncpy (dest_addr, src_addr, max_bytes) + + copy the null terminated string pointed to by src_addr to the + string pointed to by dest_addr. Return the original dest_addr. + If the source string is shorter than max_bytes, then null-pad + the destination string. If it is longer than max_bytes, the + copy stops at max_bytes bytes (and no terminating null appears + in the destination string). + + This routine will fail if the source and destination string + overlap (in particular, if the end of the source is overlapped + by the beginning of the destination). The behavior is undefined. + This is acceptable according to the draft C standard. + + Undefined behavior will also occur if the end of the source string + (i.e. the terminating null byte) is in the last two words of the + program's allocated memory space. This is so because strncpy fetches + ahead. Disallowing the fetch ahead would impose a severe performance + penalty. + + Strategy: + + Fetch and store the strings by words and go to a character move loop + as soon as a null byte is encountered. If max_bytes is exhausted + first, then terminate after moving only max_bytes (with the last + 0, 1, 2, or 3 bytes moved as single bytes, not as a word). + Otherwise, the character move loop moves the last bytes or the + source string, and then null-pads the destination string until + max_bytes is exhausted. + + Tactics: + + 1) Do NOT try to fetch the words in a word aligned manner because, + in my judgement, the performance degradation experienced due to + non-aligned accesses does NOT outweigh the time and complexity added + by the preamble and convoluted body that would be necessary to assure + alignment. + + 2) When the null byte is encountered in a source word, null out the + higher-numbered bytes in that word, store the word in the destination, + and go to the word null-padder, which may eventually go to the byte + null-padder. +*/ + + .globl _strncpy + .globl __strncpy + .leafproc _strncpy,__strncpy + .align 2 +_strncpy: +#ifndef __PIC + lda Lrett,g14 +#else + lda Lrett-(.+8)(ip),g14 +#endif +__strncpy: + mov g14, g13 + cmpibge 0,g2,Lexit # quit early if max_bytes <= 0 + ld (g1), g7 # fetch the first word of the source + mov g0, g5 + lda 0xff, g3 # byte extraction mask + addo g1, g2, g6 + addo g2, g5, g2 +Lwloop: # word copying loop + addo 4, g1, g1 # post-increment source ptr + cmpo g6, g1 # max_bytes < 4 ? + mov g7, g4 # keep a copy of source word + bl Lcloop.a # if less than four bytes to go, go to char loop + scanbyte 0, g4 # null byte found? + ld (g1), g7 # pre-fetch next word of the source + be Lcloop.c # go to char loop if null encountered + st g4, (g5) # store current word + addo 4, g5, g5 # post-increment destination ptr + b Lwloop + +Lcloop.a: # character copying loop (max_bytes < 3) + and g3, g4, g14 # extract byte +Lcloop.b: + cmpo g2, g5 # max_bytes <= 0 ? + shro 8, g4, g4 # position word to extract next byte + be Lexit # exit if max_bytes exhausted + cmpo 0, g14 # is it null? + stob g14, (g5) # store it + addo 1, g5, g5 # post-increment dest ptr + bne Lcloop.a # branch if we are NOT null padding + b Lcloop.b # branch if we are null padding + +Lexit: + mov 0, g14 + bx (g13) # g0 = dest string address; g14 = 0 +Lrett: + ret + +Lcloop.c: # character copying loop + and g3, g4, g14 # extract byte + cmpo 0, g14 # is it null? + mov g3, g7 # save mask + shlo 8, g3, g3 # shift mask to next byte position + bne Lcloop.c # loop until null found + subo 1, g7, g3 # mask to null pad after null byte + and g3, g4, g4 # null-out stuff after null byte + st g4, (g5) # store last part of src and first of null-pad + subo 8,g2,g6 # adjust max_byte counter + +Lzwloop: + cmpo g5, g6 # max_bytes < 4 ? + addo 4, g5, g5 + bg Lcloop.b # if so, goto character loop + st g14, (g5) # store four null bytes + b Lzwloop + +/* end of strncpy */ |