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+/*******************************************************************************
+ *
+ * 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 "memchr.s"
+#ifdef __PIC
+ .pic
+#endif
+#ifdef __PID
+ .pid
+#endif
+/*
+ * (c) copyright 1988,1993 Intel Corp., all rights reserved
+ */
+
+/*
+ procedure memchr (optimized assembler version for the 80960K series)
+
+ src_addr = memchr (src_addr, char, max_bytes)
+
+ searching from src_addr for a span of max_bytes bytes, return a
+ pointer to the first byte in the source array that contains the
+ indicated char. Return null if the char is not found.
+
+ Undefined behavior will occur if the last byte of the source array
+ is in the last two words of the program's allocated memory space.
+ This is so because memchr fetches ahead. Disallowing the fetch
+ ahead would impose a severe performance penalty.
+
+ Strategy:
+
+ Fetch the source array by words and scanbyte the words for the
+ char until either a word with the byte is found or max_bytes is
+ exhausted. In the former case, move through the word to find the
+ matching byte and return its memory address. In the latter case,
+ return zero (null).
+
+ 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.
+
+ 2) Rather than decrementing max_bytes to zero, I calculate the
+ address of the byte after the last byte of the source array, and
+ quit when the source byte pointer passes that. Refining, actually
+ I calculate the address of the fifth byte after the last byte of
+ the source array, because the source byte pointer is ahead of the
+ actual examination point due to fetch ahead.
+*/
+
+ .globl _memchr
+ .globl __memchr
+ .leafproc _memchr, __memchr
+ .align 2
+_memchr:
+#ifndef __PIC
+ lda Lrett,g14
+#else
+ lda Lrett-(.+8)(ip),g14
+#endif
+__memchr:
+
+ mov g14,g13 # preserve return address
+ lda 0xff,g7 # byte extraction mask
+ and g1,g7,g1 # make char an 8-bit ordinal
+ mov 0,g14 # conform to register linkage standard
+ cmpibge 0,g2,Lnot_found # do nothing if max_bytes <= 0
+ addo 4,g0,g6 # post-increment src word pointer
+ addo g2,g6,g2 # compute ending address from start and len
+ ld (g0),g4 # fetch first word
+ shlo 8,g1,g3 # broadcast the char to four bytes
+ or g1,g3,g3
+ shlo 16,g3,g5
+ or g3,g5,g3
+
+Lsearch_for_word_with_char:
+ mov g4,g5 # keep a copy of word
+ scanbyte g3,g5 # check for byte with char
+ ld (g6),g4 # fetch next word of src
+ bo Lsearch_for_char # branch if null found
+ addo 4,g6,g6 # post-increment src word pointer
+ cmpobge g2,g6,Lsearch_for_word_with_char # branch if max_bytes > 3
+
+Lnot_found:
+ mov 0,g0 # char not found. Return null
+ bx (g13) # g0 = addr of char in src (or null); g14 = 0
+Lrett:
+ ret
+
+Lsearch_for_char:
+ cmpobe.f g6,g2,Lnot_found # quit if max_bytes exhausted
+ and g5,g7,g0 # extract byte
+ cmpo g1,g0 # is it char?
+ addo 1,g6,g6 # bump src byte ptr
+ shro 8,g5,g5 # shift word to position next byte
+ bne.t Lsearch_for_char
+ subo 5,g6,g0 # back up the byte pointer
+ bx (g13)
+
+/* end of memchr */