| 1 | /* SPDX-License-Identifier: GPL-2.0 */
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| 2 | /*
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| 3 | * arch/alpha/lib/strncat.S
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| 4 | * Contributed by Richard Henderson (rth@tamu.edu)
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| 5 | *
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| 6 | * Append no more than COUNT characters from the null-terminated string SRC
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| 7 | * to the null-terminated string DST. Always null-terminate the new DST.
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| 8 | *
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| 9 | * This differs slightly from the semantics in libc in that we never write
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| 10 | * past count, whereas libc may write to count+1. This follows the generic
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| 11 | * implementation in lib/string.c and is, IMHO, more sensible.
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| 12 | */
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| 13 | |
| 14 | .text
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| 15 |
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| 16 | .align 3
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| 17 | .globl strncat
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| 18 | .ent strncat
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| 19 | strncat:
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| 20 | .frame $30, 0, $26
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| 21 | .prologue 0
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| 22 |
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| 23 | mov $16, $0 |
| 24 | beq $18, $zerocount
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| 25 |
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| 26 | /* Find the end of the string. */
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| 27 |
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| 28 | ldq_u $1, 0($16) |
| 29 | lda $2, -1($31)
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| 30 | insqh $2, $16, $2
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| 31 | andnot $16, 7, $16
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| 32 | or $2, $1, $1
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| 33 | cmpbge $31, $1, $2 |
| 34 | bne $2, $found
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| 35 |
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| 36 | $loop: ldq $1, 8($16)
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| 37 | addq $16, 8, $16
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| 38 | cmpbge $31, $1, $2
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| 39 | beq $2, $loop
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| 40 |
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| 41 | $found: negq $2, $3 |
| 42 | and $2, $3, $2
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| 43 |
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| 44 | and $2, 0xf0, $3 |
| 45 | and $2, 0xcc, $4
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| 46 | and $2, 0xaa, $5
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| 47 | cmovne $3, 4, $3
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| 48 | cmovne $4, 2, $4
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| 49 | cmovne $5, 1, $5
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| 50 | addq $3, $4, $3
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| 51 | addq $16, $5, $16
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| 52 | addq $16, $3, $16
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| 53 |
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| 54 | /* Now do the append. */
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| 55 |
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| 56 | bsr $23, __stxncpy
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| 57 |
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| 58 | /* Worry about the null termination. */
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| 59 |
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| 60 | zapnot $1, $27, $2 |
| 61 | bne $2, 0f
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| 62 | ret
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| 63 |
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| 64 | 0: cmplt $27, $24, $2 |
| 65 | or $2, $18, $2
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| 66 | bne $2, 2f
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| 67 |
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| 68 | and $24, 0x80, $2 |
| 69 | bne $2, 1f
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| 70 |
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| 71 | /* Here there are bytes left in the current word. Clear one. */
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| 72 | addq $24, $24, $24 |
| 73 | 2: zap $1, $24, $1
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| 74 | stq_u $1, 0($16)
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| 75 | ret
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| 76 |
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| 77 | 1: /* Here we must read the next DST word and clear the first byte. */
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| 78 | ldq_u $1, 8($16)
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| 79 | zap $1, 1, $1
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| 80 | stq_u $1, 8($16)
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| 81 |
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| 82 | $zerocount:
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| 83 | ret
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| 84 |
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| 85 | .end strncat
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| 86 | EXPORT_SYMBOL(strncat)
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