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82 lines
1.5 KiB
82 lines
1.5 KiB
20 years ago
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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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.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 $4, $3, $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 $24, 1, $2 # clear the final bits in the prev word
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or $2, $24, $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 $27, 1, $2
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or $2, $27, $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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