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authorMike Frysinger <vapier@gentoo.org>2006-05-30 09:13:53 +0000
committerMike Frysinger <vapier@gentoo.org>2006-05-30 09:13:53 +0000
commit4fcc031a7085a47b9a027a20a919574f8aab0768 (patch)
treeff657fef5414526db2af82bd7af016abaf8a6bd3 /libc/string/bfin/strcmp.S
parent63e3fcd76cd372cc5a30c414237b6a64d1a210dd (diff)
import some optimized functions from blackfin cvs
Diffstat (limited to 'libc/string/bfin/strcmp.S')
-rw-r--r--libc/string/bfin/strcmp.S121
1 files changed, 121 insertions, 0 deletions
diff --git a/libc/string/bfin/strcmp.S b/libc/string/bfin/strcmp.S
new file mode 100644
index 000000000..6365024ec
--- /dev/null
+++ b/libc/string/bfin/strcmp.S
@@ -0,0 +1,121 @@
+/* strcmp.S
+ * Copyright (C) 2003, 2005, 2006 Analog Devices Inc., All Rights Reserved.
+ *
+ * This file is subject to the terms and conditions of the GNU Library General
+ * Public License. See the file "COPYING.LIB" in the main directory of this
+ * archive for more details.
+ *
+ * Non-LGPL License also available as part of VisualDSP++
+ * http://www.analog.com/processors/resources/crosscore/visualDspDevSoftware.html
+ */
+
+/* Fast strcmp() for Blackfin.
+ * When both strings are aligned, this processes four characters at
+ * a time. Uses a hw loop with "very big" count to loop "forever",
+ * until difference or a terminating zero is found.
+ * Once the end-case word has been identified, breaks out of the
+ * loop to check more carefully (same as the unaligned case).
+ */
+
+.text
+
+.align 2
+
+.global _strcmp
+.type _strcmp, STT_FUNC
+_strcmp:
+ [--sp] = (R7:4);
+ p1 = r0;
+ p2 = r1;
+
+ p0 = -1; // (need for loop counter init)
+
+ // check if byte aligned
+ r0 = r0 | r1; // check both pointers at same time
+ r0 <<= 30; // dump all but last 2 bits
+ cc = az; // are they zero?
+ if !cc jump unaligned; // no; use unaligned code.
+ // fall-thru for aligned case..
+
+ // note that r0 is zero from the previous...
+ // p0 set to -1
+
+ lsetup (beginloop, endloop) lc0=p0;
+ // pick up first words
+ r1 = [p1++];
+ r2 = [p2++];
+ // make up mask: 0FF0FF
+ r7 = 0xFF;
+ r7.h = 0xFF;
+ // loop : 9 cycles to check 4 characters
+ cc = r1 == r2;
+beginloop:
+ if !cc jump notequal4; // compare failure, exit loop
+
+ // starting with 44332211
+ // see if char 3 or char 1 is 0
+ r3 = r1 & r7; // form 00330011
+ // add to zero, and (r2 is free, reload)
+ r6 = r3 +|+ r0 || r2 = [p2++] || nop;
+ cc = az; // true if either is zero
+ r3 = r1 ^ r3; // form 44002200 (4321^0301 => 4020)
+ // (trick, saves having another mask)
+ // add to zero, and (r1 is free, reload)
+ r6 = r3 +|+ r0 || r1 = [p1++] || nop;
+ cc |= az; // true if either is zero
+ if cc jump zero4; // leave if a zero somewhere
+endloop:
+ cc = r1 == r2;
+
+ // loop exits
+notequal4: // compare failure on 4-char compare
+ // address pointers are one word ahead;
+ // faster to use zero4 exit code
+ p1 += 4;
+ p2 += 4;
+
+zero4: // one of the bytes in word 1 is zero
+ // but we've already fetched the next word; so
+ // backup two to look at failing word again
+ p1 += -8;
+ p2 += -8;
+
+
+
+ // here when pointers are unaligned: checks one
+ // character at a time. Also use at the end of
+ // the word-check algorithm to figure out what happened
+unaligned:
+ // R0 is non-zero from before.
+ // p0 set to -1
+
+ r0 = 0 (Z);
+ r1 = B[p1++] (Z);
+ r2 = B[p2++] (Z);
+ lsetup (beginloop1, endloop1) lc0=p0;
+
+beginloop1:
+ cc = r1; // first char must be non-zero
+ // chars must be the same
+ r3 = r2 - r1 (NS) || r1 = B[p1++] (Z) || nop;
+ cc &= az;
+ r3 = r0 - r2; // second char must be non-zero
+ cc &= an;
+ if !cc jump exitloop1;
+endloop1:
+ r2 = B[p2++] (Z);
+
+exitloop1: // here means we found a zero or a difference.
+ // we have r2(N), p2(N), r1(N+1), p1(N+2)
+ r1=B[p1+ -2] (Z);
+ r0 = r1 - r2;
+ (r7:4) = [sp++];
+ rts;
+.size _strcmp,.-_strcmp
+
+libc_hidden_def (strcmp)
+
+#ifndef __UCLIBC_HAS_LOCALE__
+strong_alias (strcmp,strcoll)
+libc_hidden_def (strcoll)
+#endif