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83 lines
1.5 KiB
83 lines
1.5 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* arch/alpha/lib/strncpy.S |
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* Contributed by Richard Henderson (rth@tamu.edu) |
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* |
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* Copy no more than COUNT bytes of the null-terminated string from |
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* SRC to DST. If SRC does not cover all of COUNT, the balance is |
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* zeroed. |
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* |
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* Or, rather, if the kernel cared about that weird ANSI quirk. This |
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* version has cropped that bit o' nastiness as well as assuming that |
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* __stxncpy is in range of a branch. |
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*/ |
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#include <asm/export.h> |
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.set noat |
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.set noreorder |
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.text |
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.align 4 |
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.globl strncpy |
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.ent strncpy |
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strncpy: |
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.frame $30, 0, $26 |
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.prologue 0 |
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mov $16, $0 # set return value now |
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beq $18, $zerolen |
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unop |
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bsr $23, __stxncpy # do the work of the copy |
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unop |
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bne $18, $multiword # do we have full words left? |
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subq $24, 1, $3 # nope |
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subq $27, 1, $4 |
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or $3, $24, $3 # clear the bits between the last |
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or $4, $27, $4 # written byte and the last byte in COUNT |
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andnot $3, $4, $4 |
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zap $1, $4, $1 |
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stq_u $1, 0($16) |
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ret |
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.align 4 |
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$multiword: |
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subq $27, 1, $2 # clear the final bits in the prev word |
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or $2, $27, $2 |
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zapnot $1, $2, $1 |
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subq $18, 1, $18 |
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stq_u $1, 0($16) |
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addq $16, 8, $16 |
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unop |
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beq $18, 1f |
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nop |
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unop |
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nop |
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blbc $18, 0f |
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stq_u $31, 0($16) # zero one word |
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subq $18, 1, $18 |
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addq $16, 8, $16 |
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beq $18, 1f |
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0: stq_u $31, 0($16) # zero two words |
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subq $18, 2, $18 |
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stq_u $31, 8($16) |
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addq $16, 16, $16 |
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bne $18, 0b |
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1: ldq_u $1, 0($16) # clear the leading bits in the final word |
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subq $24, 1, $2 |
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or $2, $24, $2 |
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zap $1, $2, $1 |
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stq_u $1, 0($16) |
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$zerolen: |
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ret |
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.end strncpy |
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EXPORT_SYMBOL(strncpy)
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