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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/strchr.S
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.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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diff --git a/arch/alpha/lib/strchr.S b/arch/alpha/lib/strchr.S
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+/*
+ * arch/alpha/lib/strchr.S
+ * Contributed by Richard Henderson (rth@tamu.edu)
+ *
+ * Return the address of a given character within a null-terminated
+ * string, or null if it is not found.
+ */
+
+#include <asm/regdef.h>
+
+ .set noreorder
+ .set noat
+
+ .align 3
+ .globl strchr
+ .ent strchr
+strchr:
+ .frame sp, 0, ra
+ .prologue 0
+
+ zapnot a1, 1, a1 # e0 : zero extend the search character
+ ldq_u t0, 0(a0) # .. e1 : load first quadword
+ sll a1, 8, t5 # e0 : replicate the search character
+ andnot a0, 7, v0 # .. e1 : align our loop pointer
+ or t5, a1, a1 # e0 :
+ lda t4, -1 # .. e1 : build garbage mask
+ sll a1, 16, t5 # e0 :
+ cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
+ mskqh t4, a0, t4 # e0 :
+ or t5, a1, a1 # .. e1 :
+ sll a1, 32, t5 # e0 :
+ cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
+ or t5, a1, a1 # e0 :
+ xor t0, a1, t1 # .. e1 : make bytes == c zero
+ cmpbge zero, t1, t3 # e0 : bits set iff byte == c
+ or t2, t3, t0 # e1 : bits set iff char match or zero match
+ andnot t0, t4, t0 # e0 : clear garbage bits
+ bne t0, $found # .. e1 (zdb)
+
+$loop: ldq t0, 8(v0) # e0 :
+ addq v0, 8, v0 # .. e1 :
+ nop # e0 :
+ xor t0, a1, t1 # .. e1 (ev5 data stall)
+ cmpbge zero, t0, t2 # e0 : bits set iff byte == 0
+ cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c
+ or t2, t3, t0 # e0 :
+ beq t0, $loop # .. e1 (zdb)
+
+$found: negq t0, t1 # e0 : clear all but least set bit
+ and t0, t1, t0 # e1 (stall)
+
+ and t0, t3, t1 # e0 : bit set iff byte was the char
+ beq t1, $retnull # .. e1 (zdb)
+
+ and t0, 0xf0, t2 # e0 : binary search for that set bit
+ and t0, 0xcc, t3 # .. e1 :
+ and t0, 0xaa, t4 # e0 :
+ cmovne t2, 4, t2 # .. e1 :
+ cmovne t3, 2, t3 # e0 :
+ cmovne t4, 1, t4 # .. e1 :
+ addq t2, t3, t2 # e0 :
+ addq v0, t4, v0 # .. e1 :
+ addq v0, t2, v0 # e0 :
+ ret # .. e1 :
+
+$retnull:
+ mov zero, v0 # e0 :
+ ret # .. e1 :
+
+ .end strchr