diff options
Diffstat (limited to 'arch/alpha/lib/ev67-strchr.S')
-rw-r--r-- | arch/alpha/lib/ev67-strchr.S | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/arch/alpha/lib/ev67-strchr.S b/arch/alpha/lib/ev67-strchr.S new file mode 100644 index 000000000000..fbb7b4ffade9 --- /dev/null +++ b/arch/alpha/lib/ev67-strchr.S | |||
@@ -0,0 +1,88 @@ | |||
1 | /* | ||
2 | * arch/alpha/lib/ev67-strchr.S | ||
3 | * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com> | ||
4 | * | ||
5 | * Return the address of a given character within a null-terminated | ||
6 | * string, or null if it is not found. | ||
7 | * | ||
8 | * Much of the information about 21264 scheduling/coding comes from: | ||
9 | * Compiler Writer's Guide for the Alpha 21264 | ||
10 | * abbreviated as 'CWG' in other comments here | ||
11 | * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html | ||
12 | * Scheduling notation: | ||
13 | * E - either cluster | ||
14 | * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 | ||
15 | * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 | ||
16 | * Try not to change the actual algorithm if possible for consistency. | ||
17 | */ | ||
18 | |||
19 | #include <asm/regdef.h> | ||
20 | |||
21 | .set noreorder | ||
22 | .set noat | ||
23 | |||
24 | .align 4 | ||
25 | .globl strchr | ||
26 | .ent strchr | ||
27 | strchr: | ||
28 | .frame sp, 0, ra | ||
29 | .prologue 0 | ||
30 | |||
31 | ldq_u t0, 0(a0) # L : load first quadword Latency=3 | ||
32 | and a1, 0xff, t3 # E : 00000000000000ch | ||
33 | insbl a1, 1, t5 # U : 000000000000ch00 | ||
34 | insbl a1, 7, a2 # U : ch00000000000000 | ||
35 | |||
36 | insbl t3, 6, a3 # U : 00ch000000000000 | ||
37 | or t5, t3, a1 # E : 000000000000chch | ||
38 | andnot a0, 7, v0 # E : align our loop pointer | ||
39 | lda t4, -1 # E : build garbage mask | ||
40 | |||
41 | mskqh t4, a0, t4 # U : only want relevant part of first quad | ||
42 | or a2, a3, a2 # E : chch000000000000 | ||
43 | inswl a1, 2, t5 # E : 00000000chch0000 | ||
44 | inswl a1, 4, a3 # E : 0000chch00000000 | ||
45 | |||
46 | or a1, a2, a1 # E : chch00000000chch | ||
47 | or a3, t5, t5 # E : 0000chchchch0000 | ||
48 | cmpbge zero, t0, t2 # E : bits set iff byte == zero | ||
49 | cmpbge zero, t4, t4 # E : bits set iff byte is garbage | ||
50 | |||
51 | /* This quad is _very_ serialized. Lots of stalling happens */ | ||
52 | or t5, a1, a1 # E : chchchchchchchch | ||
53 | xor t0, a1, t1 # E : make bytes == c zero | ||
54 | cmpbge zero, t1, t3 # E : bits set iff byte == c | ||
55 | or t2, t3, t0 # E : bits set iff char match or zero match | ||
56 | |||
57 | andnot t0, t4, t0 # E : clear garbage bits | ||
58 | cttz t0, a2 # U0 : speculative (in case we get a match) | ||
59 | nop # E : | ||
60 | bne t0, $found # U : | ||
61 | |||
62 | /* | ||
63 | * Yuk. This loop is going to stall like crazy waiting for the | ||
64 | * data to be loaded. Not much can be done about it unless it's | ||
65 | * unrolled multiple times - is that safe to do in kernel space? | ||
66 | * Or would exception handling recovery code do the trick here? | ||
67 | */ | ||
68 | $loop: ldq t0, 8(v0) # L : Latency=3 | ||
69 | addq v0, 8, v0 # E : | ||
70 | xor t0, a1, t1 # E : | ||
71 | cmpbge zero, t0, t2 # E : bits set iff byte == 0 | ||
72 | |||
73 | cmpbge zero, t1, t3 # E : bits set iff byte == c | ||
74 | or t2, t3, t0 # E : | ||
75 | cttz t3, a2 # U0 : speculative (in case we get a match) | ||
76 | beq t0, $loop # U : | ||
77 | |||
78 | $found: negq t0, t1 # E : clear all but least set bit | ||
79 | and t0, t1, t0 # E : | ||
80 | and t0, t3, t1 # E : bit set iff byte was the char | ||
81 | addq v0, a2, v0 # E : Add in the bit number from above | ||
82 | |||
83 | cmoveq t1, $31, v0 # E : Two mapping slots, latency = 2 | ||
84 | nop | ||
85 | nop | ||
86 | ret # L0 : | ||
87 | |||
88 | .end strchr | ||