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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/alpha/lib/ev67-strcat.S
downloadlinux-stericsson-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * arch/alpha/lib/ev67-strcat.S
+ * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
+ *
+ * Append a null-terminated string from SRC to DST.
+ *
+ * Much of the information about 21264 scheduling/coding comes from:
+ * Compiler Writer's Guide for the Alpha 21264
+ * abbreviated as 'CWG' in other comments here
+ * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
+ * Scheduling notation:
+ * E - either cluster
+ * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
+ * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
+ * Try not to change the actual algorithm if possible for consistency.
+ * Commentary: It seems bogus to walk the input string twice - once
+ * to determine the length, and then again while doing the copy.
+ * A significant (future) enhancement would be to only read the input
+ * string once.
+ */
+
+
+ .text
+
+ .align 4
+ .globl strcat
+ .ent strcat
+strcat:
+ .frame $30, 0, $26
+ .prologue 0
+
+ mov $16, $0 # E : set up return value
+ /* Find the end of the string. */
+ ldq_u $1, 0($16) # L : load first quadword (a0 may be misaligned)
+ lda $2, -1 # E :
+ insqh $2, $16, $2 # U :
+
+ andnot $16, 7, $16 # E :
+ or $2, $1, $1 # E :
+ cmpbge $31, $1, $2 # E : bits set iff byte == 0
+ bne $2, $found # U :
+
+$loop: ldq $1, 8($16) # L :
+ addq $16, 8, $16 # E :
+ cmpbge $31, $1, $2 # E :
+ beq $2, $loop # U :
+
+$found: cttz $2, $3 # U0 :
+ addq $16, $3, $16 # E :
+ /* Now do the append. */
+ mov $26, $23 # E :
+ br __stxcpy # L0 :
+
+ .end strcat