Linux-2.6.12-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!

1 files changed, 191 insertions, 0 deletions

diff --git a/arch/alpha/lib/ev6-memchr.S b/arch/alpha/lib/ev6-memchr.S
new file mode 100644
index 00000000000..a8e843dbcc2
--- /dev/null
+++ b/arch/alpha/lib/ev6-memchr.S
@@ -0,0 +1,191 @@
+/*
+ * arch/alpha/lib/ev6-memchr.S
+ *
+ * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
+ *
+ * Finds characters in a memory area.  Optimized for the Alpha:
+ *
+ *    - memory accessed as aligned quadwords only
+ *    - uses cmpbge to compare 8 bytes in parallel
+ *    - does binary search to find 0 byte in last
+ *      quadword (HAKMEM needed 12 instructions to
+ *      do this instead of the 9 instructions that
+ *      binary search needs).
+ *
+ * For correctness consider that:
+ *
+ *    - only minimum number of quadwords may be accessed
+ *    - the third argument is an unsigned long
+ *
+ * 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.
+ */
+
+        .set noreorder
+        .set noat
+
+	.align	4
+	.globl memchr
+	.ent memchr
+memchr:
+	.frame $30,0,$26,0
+	.prologue 0
+
+	# Hack -- if someone passes in (size_t)-1, hoping to just
+	# search til the end of the address space, we will overflow
+	# below when we find the address of the last byte.  Given
+	# that we will never have a 56-bit address space, cropping
+	# the length is the easiest way to avoid trouble.
+	zap	$18, 0x80, $5	# U : Bound length
+	beq	$18, $not_found	# U :
+        ldq_u   $1, 0($16)	# L : load first quadword Latency=3
+	and	$17, 0xff, $17	# E : L L U U : 00000000000000ch
+
+	insbl	$17, 1, $2	# U : 000000000000ch00
+	cmpult	$18, 9, $4	# E : small (< 1 quad) string?
+	or	$2, $17, $17	# E : 000000000000chch
+        lda     $3, -1($31)	# E : U L L U
+
+	sll	$17, 16, $2	# U : 00000000chch0000
+	addq	$16, $5, $5	# E : Max search address
+	or	$2, $17, $17	# E : 00000000chchchch
+	sll	$17, 32, $2	# U : U L L U : chchchch00000000
+
+	or	$2, $17, $17	# E : chchchchchchchch
+	extql	$1, $16, $7	# U : $7 is upper bits
+	beq	$4, $first_quad	# U :
+	ldq_u	$6, -1($5)	# L : L U U L : eight or less bytes to search Latency=3
+
+	extqh	$6, $16, $6	# U : 2 cycle stall for $6
+	mov	$16, $0		# E :
+	nop			# E :
+	or	$7, $6, $1	# E : L U L U $1 = quadword starting at $16
+
+	# Deal with the case where at most 8 bytes remain to be searched
+	# in $1.  E.g.:
+	#	$18 = 6
+	#	$1 = ????c6c5c4c3c2c1
+$last_quad:
+	negq	$18, $6		# E :
+        xor	$17, $1, $1	# E :
+	srl	$3, $6, $6	# U : $6 = mask of $18 bits set
+        cmpbge  $31, $1, $2	# E : L U L U
+
+	nop
+	nop
+	and	$2, $6, $2	# E :
+        beq     $2, $not_found	# U : U L U L
+
+$found_it:
+#if defined(__alpha_fix__) && defined(__alpha_cix__)
+	/*
+	 * Since we are guaranteed to have set one of the bits, we don't
+	 * have to worry about coming back with a 0x40 out of cttz...
+	 */
+	cttz	$2, $3		# U0 :
+	addq	$0, $3, $0	# E : All done
+	nop			# E :
+	ret			# L0 : L U L U
+#else
+	/*
+	 * Slow and clunky.  It can probably be improved.
+	 * An exercise left for others.
+	 */
+        negq    $2, $3		# E :
+        and     $2, $3, $2	# E :
+        and     $2, 0x0f, $1	# E :
+        addq    $0, 4, $3	# E :
+
+        cmoveq  $1, $3, $0	# E : Latency 2, extra map cycle
+	nop			# E : keep with cmov
+        and     $2, 0x33, $1	# E :
+        addq    $0, 2, $3	# E : U L U L : 2 cycle stall on $0
+
+        cmoveq  $1, $3, $0	# E : Latency 2, extra map cycle
+	nop			# E : keep with cmov
+        and     $2, 0x55, $1	# E :
+        addq    $0, 1, $3	# E : U L U L : 2 cycle stall on $0
+
+        cmoveq  $1, $3, $0	# E : Latency 2, extra map cycle
+	nop
+	nop
+	ret			# L0 : L U L U
+#endif
+
+	# Deal with the case where $18 > 8 bytes remain to be
+	# searched.  $16 may not be aligned.
+	.align 4
+$first_quad:
+	andnot	$16, 0x7, $0	# E :
+        insqh   $3, $16, $2	# U : $2 = 0000ffffffffffff ($16<0:2> ff)
+        xor	$1, $17, $1	# E :
+	or	$1, $2, $1	# E : U L U L $1 = ====ffffffffffff
+
+        cmpbge  $31, $1, $2	# E :
+        bne     $2, $found_it	# U :
+	# At least one byte left to process.
+	ldq	$1, 8($0)	# L :
+	subq	$5, 1, $18	# E : U L U L
+
+	addq	$0, 8, $0	# E :
+	# Make $18 point to last quad to be accessed (the
+	# last quad may or may not be partial).
+	andnot	$18, 0x7, $18	# E :
+	cmpult	$0, $18, $2	# E :
+	beq	$2, $final	# U : U L U L
+
+	# At least two quads remain to be accessed.
+
+	subq	$18, $0, $4	# E : $4 <- nr quads to be processed
+	and	$4, 8, $4	# E : odd number of quads?
+	bne	$4, $odd_quad_count # U :
+	# At least three quads remain to be accessed
+	mov	$1, $4		# E : L U L U : move prefetched value to correct reg
+
+	.align	4
+$unrolled_loop:
+	ldq	$1, 8($0)	# L : prefetch $1
+	xor	$17, $4, $2	# E :
+	cmpbge	$31, $2, $2	# E :
+	bne	$2, $found_it	# U : U L U L
+
+	addq	$0, 8, $0	# E :
+	nop			# E :
+	nop			# E :
+	nop			# E :
+
+$odd_quad_count:
+	xor	$17, $1, $2	# E :
+	ldq	$4, 8($0)	# L : prefetch $4
+	cmpbge	$31, $2, $2	# E :
+	addq	$0, 8, $6	# E :
+
+	bne	$2, $found_it	# U :
+	cmpult	$6, $18, $6	# E :
+	addq	$0, 8, $0	# E :
+	nop			# E :
+
+	bne	$6, $unrolled_loop # U :
+	mov	$4, $1		# E : move prefetched value into $1
+	nop			# E :
+	nop			# E :
+
+$final:	subq	$5, $0, $18	# E : $18 <- number of bytes left to do
+	nop			# E :
+	nop			# E :
+	bne	$18, $last_quad	# U :
+
+$not_found:
+	mov	$31, $0		# E :
+	nop			# E :
+	nop			# E :
+	ret			# L0 :
+
+        .end memchr