summaryrefslogtreecommitdiff
path: root/newlib/libc/machine/i960/strcmp.S
diff options
context:
space:
mode:
Diffstat (limited to 'newlib/libc/machine/i960/strcmp.S')
-rw-r--r--newlib/libc/machine/i960/strcmp.S118
1 files changed, 118 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strcmp.S b/newlib/libc/machine/i960/strcmp.S
new file mode 100644
index 00000000000..c0cd4bd6f95
--- /dev/null
+++ b/newlib/libc/machine/i960/strcmp.S
@@ -0,0 +1,118 @@
+/*******************************************************************************
+ *
+ * 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 "strcmp.s"
+#ifdef __PIC
+ .pic
+#endif
+#ifdef __PID
+ .pid
+#endif
+/*
+ * (c) copyright 1988,1993 Intel Corp., all rights reserved
+ */
+/*
+ procedure strcmp (optimized assembler version for the 80960K Series)
+
+ result = strcmp (src1_addr, src2_addr)
+
+ compare the null terminated string pointed to by src1_addr to
+ the string pointed to by src2_addr. Return 0 iff the strings
+ are equal, -1 if src1_addr is lexicographically less than src2_addr,
+ and 1 if it is lexicographically greater.
+
+ Undefined behavior will occur if the end of either 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 strcmp fetches
+ ahead. Disallowing the fetch ahead would impose a severe performance
+ penalty.
+
+ Strategy:
+
+ Fetch the source strings by words and compare the words until either
+ differing words are found or the null byte is encountered. In either
+ case, move through the word until either the differing byte if found,
+ in which case return -1 or 1 appropriately; or the null byte is
+ encountered, in which case, return zero (equality).
+
+ 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. This is supported by the intuition that many source
+ strings will be word aligned to begin with.
+*/
+
+ .globl _strcmp
+ .globl __strcmp
+ .leafproc _strcmp,__strcmp
+ .align 2
+
+_strcmp:
+#ifndef __PIC
+ lda .Lrett,g14
+#else
+ lda .Lrett-(.+8)(ip),g14
+#endif
+__strcmp:
+ ld (g0), g5 # fetch first word of source_1
+ mov g14,g7 # preserve return address
+ ldconst 0,g14 # conform to register conventions
+ ldconst 0xff,g4 # byte extraction mask
+.Lwloop:
+ addo 4,g0,g0 # post-increment source_1 byte ptr
+ ld (g1), g3 # fetch word of source_2
+ scanbyte 0,g5 # does word have a null byte?
+ mov g5,g2 # save a copy of the source_1 word
+ be .Lcloop # branch if null byte encountered
+ cmpo g2,g3 # are the source words the same?
+ addo 4,g1,g1 # post-increment source_2 byte ptr
+ ld (g0), g5 # fetch ahead next word of source_1
+ be .Lwloop # fall thru if words are unequal
+
+.Lcloop: and g4,g2,g5 # extract and compare individual bytes
+ and g4,g3,g6
+ cmpobne g5,g6,.diff # if they differ, go return 1 or -1
+ cmpo 0,g6 # they are the same. Are they null?
+ shlo 8,g4,g4 # position mask for next extraction
+ bne .Lcloop # loop if null not encountered
+
+ mov 0,g0 # return equality
+ bx (g7)
+.Lrett:
+ ret
+.diff: bl .neg
+ mov 1,g0
+ bx (g7)
+.neg: subi 1,0,g0
+.Lexit:
+ bx (g7)