Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * arch/alpha/lib/ev67-strcat.S | |
3 | * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com> | |
4 | * | |
5 | * Append a null-terminated string from SRC to DST. | |
6 | * | |
7 | * Much of the information about 21264 scheduling/coding comes from: | |
8 | * Compiler Writer's Guide for the Alpha 21264 | |
9 | * abbreviated as 'CWG' in other comments here | |
10 | * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html | |
11 | * Scheduling notation: | |
12 | * E - either cluster | |
13 | * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 | |
14 | * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 | |
15 | * Try not to change the actual algorithm if possible for consistency. | |
16 | * Commentary: It seems bogus to walk the input string twice - once | |
17 | * to determine the length, and then again while doing the copy. | |
18 | * A significant (future) enhancement would be to only read the input | |
19 | * string once. | |
20 | */ | |
21 | ||
22 | ||
23 | .text | |
24 | ||
25 | .align 4 | |
26 | .globl strcat | |
27 | .ent strcat | |
28 | strcat: | |
29 | .frame $30, 0, $26 | |
30 | .prologue 0 | |
31 | ||
32 | mov $16, $0 # E : set up return value | |
33 | /* Find the end of the string. */ | |
34 | ldq_u $1, 0($16) # L : load first quadword (a0 may be misaligned) | |
35 | lda $2, -1 # E : | |
36 | insqh $2, $16, $2 # U : | |
37 | ||
38 | andnot $16, 7, $16 # E : | |
39 | or $2, $1, $1 # E : | |
40 | cmpbge $31, $1, $2 # E : bits set iff byte == 0 | |
41 | bne $2, $found # U : | |
42 | ||
43 | $loop: ldq $1, 8($16) # L : | |
44 | addq $16, 8, $16 # E : | |
45 | cmpbge $31, $1, $2 # E : | |
46 | beq $2, $loop # U : | |
47 | ||
48 | $found: cttz $2, $3 # U0 : | |
49 | addq $16, $3, $16 # E : | |
50 | /* Now do the append. */ | |
51 | mov $26, $23 # E : | |
52 | br __stxcpy # L0 : | |
53 | ||
54 | .end strcat |