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