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Diffstat (limited to 'newlib/libc/machine/i960/strncat.S')
| -rw-r--r-- | newlib/libc/machine/i960/strncat.S | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strncat.S b/newlib/libc/machine/i960/strncat.S new file mode 100644 index 00000000000..a655824eaad --- /dev/null +++ b/newlib/libc/machine/i960/strncat.S @@ -0,0 +1,155 @@ +/******************************************************************************* + * + * 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 "strncat.s" +#ifdef __PIC + .pic +#endif +#ifdef __PID + .pid +#endif +/* + * (c) copyright 1988,1993 Intel Corp., all rights reserved + */ +/* + procedure strncat (optimized assembler version for the 80960K Series) + + dest_addr = strncat (dest_addr, src_addr, max_bytes) + + append the null terminated string pointed to by src_addr to the null + terminated string pointed to by dest_addr. Return the original + dest_addr. If the source string is longer than max_bytes, then + append only max_bytes bytes, and tack on a null byte on the end. + + 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 strncat fetches + ahead. Disallowing the fetch ahead would impose a severe performance + penalty. + + Strategy: + + First, skip to the null byte in the destination string. Then + fetch the source string by words and store them by words to the + destination string, until there are fewer than three bytes left + to copy. Then, using the last word of the source (the one that + contains the remaining 0, 1, 2, or 3 bytes to be copied), store + a byte at a time until Ldone. + + If, before exhausting the max_byte count, the null byte is encountered + in the source string, then just copy up thru the null byte. + + Tactics: + + 1) Do NOT try to fetch and store 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. +*/ + + .globl _strncat + .globl __strncat + .leafproc _strncat,__strncat + .align 2 +_strncat: +#ifndef __PIC + lda Lrett,g14 +#else + lda Lrett-(.+8)(ip),g14 +#endif +__strncat: + mov g14,g6 + cmpibge 0, g2, Lno_operation # Lexit early if max_bytes <= 0 + mov g0, g5 +Lskip_word_loop: + ld (g5), g7 # fetch word of dest string + addo 4, g5, g5 # post-increment dest ptr + scanbyte 0, g7 # does it contain null byte? + bno Lskip_word_loop # if not, loop + subo 5, g5, g5 # adjust dest ptr + lda 0xff, g3 # byte extraction mask = 0xff; +Lskip_byte_loop: + and g7, g3, g14 # extract byte of last word of dest string + cmpo 0, g14 # is it null? + addo 1, g5, g5 # adjust dest ptr + shro 8, g7, g7 # position next byte for extraction + bne Lskip_byte_loop # loop if null not found yet + + ld (g1), g7 # fetch first word of source string +Lwloop: # word copying loop + cmpo 4, g2 # max_bytes < 4 ? + addo 4, g1, g1 # post-increment source ptr + bge Lcloop.a # branch if less than 4 bytes to move + scanbyte 0, g7 # is null byte reached yet? + mov g7, g4 # keep a copy of the source word + be Lcloop # branch if null byte reached + ld (g1), g7 # pre-fetch next word of source + subo 4, g2, g2 # reduce max_byte counter + st g4, (g5) # store current word + addo 4, g5, g5 # post-increment destination ptr + b Lwloop + +Lcloop.b: + addo 1, g5, g5 # post-increment destination ptr + shro 8, g7, g7 # position next byte for extraction +Lcloop: # character copying loop (max_byte > 3) + and g3, g7, g4 # extract character + cmpo 0, g4 # is it null? + stob g4, (g5) # store it + bne Lcloop.b # loop if null not encountered yet + + bx (g6) # g0 = dest string address; g14 = 0 +Lrett: + ret + +Lcloop.c: + addo 1, g5, g5 # post-increment destination ptr + shro 8, g7, g7 # position next byte for extraction +Lcloop.a: # character copying loop (max_byte <= 3) + cmpdeco 0,g2,g2 # max_byte == 0? + and g3, g7, g4 # extract character + be Ldone # store null and Lexit if max_byte exhausted + cmpo 0, g4 # is it null? + stob g4, (g5) # store it + bne Lcloop.c # loop if null not encountered yet + +Ldone: stob g14, (g5) # store trailing null + bx (g6) # g0 = dest string address; g14 = 0 + +Lno_operation: mov 0, g14 # conform to register conventions + bx (g6) + +/* end of strncat */ |