diff options
Diffstat (limited to 'newlib/libc/machine/i960/strrchr.S')
| -rw-r--r-- | newlib/libc/machine/i960/strrchr.S | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strrchr.S b/newlib/libc/machine/i960/strrchr.S new file mode 100644 index 0000000..96fe5c2 --- /dev/null +++ b/newlib/libc/machine/i960/strrchr.S @@ -0,0 +1,137 @@ +/******************************************************************************* + * + * 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 "strrchr.s" +#ifdef __i960_BIG_ENDIAN__ +#error "This does not work in big-endian" +#endif + +#ifdef __PIC + .pic +#endif +#ifdef __PID + .pid +#endif + +/* + * (c) copyright 1988,1993 Intel Corp., all rights reserved + */ + +/* + procedure strrchr (optimized assembler version for the 80960K series) + + src_addr = strrchr (src_addr, char) + + return a pointer to the last byte that contains the indicated + byte in the source string. Return null if the byte is not found. + + Undefined behavior will 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 strrchr fetches ahead. + Disallowing the fetch ahead would impose a severe performance penalty. + + Strategy: + + Fetch the source string by words and scanbyte the words for the + char until either a word with the byte is found or the null byte is + encountered. In the former case, move through the word to find the + matching byte and save its memory address, then continue the search. + In the latter case, return the saved address, or zero (null) if none + was ever found to save. + + 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 that would be necessary to assure alignment. This + is supported by the intuition that most source arrays (even more + true of most big source arrays) will be word aligned to begin with. +*/ + + .globl _strrchr + .globl __strrchr + .leafproc _strrchr, __strrchr + .align 2 +_strrchr: +#ifdef __PIC + lda Lrett-(.+8)(ip),g14 +#else + lda Lrett,g14 +#endif +__strrchr: + + ld (g0),g4 # fetch first word + lda 0xff,g7 # byte extraction mask + and g1,g7,g1 # make char an 8-bit ordinal + shlo 8,g1,g2 # broadcast the char to four bytes + or g1,g2,g2 + shlo 16,g2,g5 + or g2,g5,g3 + mov g14,g13 # preserve return address + addo 4,g0,g2 # post-increment src pointer + mov 1,g0 # prepare to return null pointer + mov g3,g6 # prepare to return null pointer + +Lsearch_for_word_with_char_or_null: + mov g4,g5 # copy word + scanbyte 0,g5 # check for null byte + ld (g2),g4 # fetch next word of src + bo Lword_has_null # branch if null found + scanbyte g3,g5 # check for byte with char + addo 4,g2,g2 # post-increment src pointer + bno Lsearch_for_word_with_char_or_null # branch if no copy of char + mov g5,g6 # save word that has char in it (at least once) + subo 4,g2,g0 # save addr of byte after word with char + b Lsearch_for_word_with_char_or_null + +Lword_has_null: + subo 4,g2,g2 # move src pointer back to word with null +Lfind_null: + addo 1,g2,g2 # advance src pointer to byte after current + and g7,g5,g14 # extract next byte + cmpo g1,g14 # is current byte char? + shro 8,g5,g5 # position next byte for extraction + bne 1f # skip if not char sought after + mov g2,g0 # save addr of byte after char + mov g3,g6 # save word of all char to short circuit search +1: cmpobne 0,g14,Lfind_null # is current byte null? + +Lfind_last_char: + rotate 8,g6,g6 # position next highest byte + and g7,g6,g5 # extract byte + subo 1,g0,g0 # move pointer to that byte (or nullify) + cmpobne g5,g1,Lfind_last_char # branch if not at char + + bx (g13) # g0 = addr of char in src (or null); g14 = 0 +Lrett: + ret + +/* end of strrchr */ |