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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * arch/alpha/lib/strchr.S | |
3 | * Contributed by Richard Henderson (rth@tamu.edu) | |
4 | * | |
5 | * Return the address of a given character within a null-terminated | |
6 | * string, or null if it is not found. | |
7 | */ | |
8 | ||
9 | #include <asm/regdef.h> | |
10 | ||
11 | .set noreorder | |
12 | .set noat | |
13 | ||
14 | .align 3 | |
15 | .globl strchr | |
16 | .ent strchr | |
17 | strchr: | |
18 | .frame sp, 0, ra | |
19 | .prologue 0 | |
20 | ||
21 | zapnot a1, 1, a1 # e0 : zero extend the search character | |
22 | ldq_u t0, 0(a0) # .. e1 : load first quadword | |
23 | sll a1, 8, t5 # e0 : replicate the search character | |
24 | andnot a0, 7, v0 # .. e1 : align our loop pointer | |
25 | or t5, a1, a1 # e0 : | |
26 | lda t4, -1 # .. e1 : build garbage mask | |
27 | sll a1, 16, t5 # e0 : | |
28 | cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero | |
29 | mskqh t4, a0, t4 # e0 : | |
30 | or t5, a1, a1 # .. e1 : | |
31 | sll a1, 32, t5 # e0 : | |
32 | cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage | |
33 | or t5, a1, a1 # e0 : | |
34 | xor t0, a1, t1 # .. e1 : make bytes == c zero | |
35 | cmpbge zero, t1, t3 # e0 : bits set iff byte == c | |
36 | or t2, t3, t0 # e1 : bits set iff char match or zero match | |
37 | andnot t0, t4, t0 # e0 : clear garbage bits | |
38 | bne t0, $found # .. e1 (zdb) | |
39 | ||
40 | $loop: ldq t0, 8(v0) # e0 : | |
41 | addq v0, 8, v0 # .. e1 : | |
42 | nop # e0 : | |
43 | xor t0, a1, t1 # .. e1 (ev5 data stall) | |
44 | cmpbge zero, t0, t2 # e0 : bits set iff byte == 0 | |
45 | cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c | |
46 | or t2, t3, t0 # e0 : | |
47 | beq t0, $loop # .. e1 (zdb) | |
48 | ||
49 | $found: negq t0, t1 # e0 : clear all but least set bit | |
50 | and t0, t1, t0 # e1 (stall) | |
51 | ||
52 | and t0, t3, t1 # e0 : bit set iff byte was the char | |
53 | beq t1, $retnull # .. e1 (zdb) | |
54 | ||
55 | and t0, 0xf0, t2 # e0 : binary search for that set bit | |
56 | and t0, 0xcc, t3 # .. e1 : | |
57 | and t0, 0xaa, t4 # e0 : | |
58 | cmovne t2, 4, t2 # .. e1 : | |
59 | cmovne t3, 2, t3 # e0 : | |
60 | cmovne t4, 1, t4 # .. e1 : | |
61 | addq t2, t3, t2 # e0 : | |
62 | addq v0, t4, v0 # .. e1 : | |
63 | addq v0, t2, v0 # e0 : | |
64 | ret # .. e1 : | |
65 | ||
66 | $retnull: | |
67 | mov zero, v0 # e0 : | |
68 | ret # .. e1 : | |
69 | ||
70 | .end strchr |