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81 lines
2.7 KiB
ArmAsm
81 lines
2.7 KiB
ArmAsm
/*
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* Copyright (c) 1983 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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.asciz "@(#)strncpy.s 5.6 (Berkeley) 6/1/90"
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#endif /* LIBC_SCCS and not lint */
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/*
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* Copy string s2 over top of string s1.
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* Truncate or null-pad to n bytes.
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*
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* char *
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* strncpy(s1, s2, n)
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* char *s1, *s2;
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*/
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#include "DEFS.h"
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ENTRY(strncpy, R6)
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movl 12(ap),r6 # r6 = n
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bleq done # n <= 0
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movl 4(ap),r3 # r3 = s1
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movl 8(ap),r1 # r1 = s2
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1:
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movzwl $65535,r2 # r2 = bytes in first chunk
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cmpl r6,r2 # r2 = min(bytes in chunk, n);
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jgeq 2f
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movl r6,r2
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2:
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subl2 r2,r6 # update n
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locc $0,r2,(r1) # '\0' found?
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jneq 3f
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subl2 r2,r1 # back up pointer updated by locc
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movc3 r2,(r1),(r3) # copy in next piece
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tstl r6 # run out of space?
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jneq 1b
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jbr done
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3: # copy up to '\0' logic
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addl2 r0,r6 # r6 = number of null-pad bytes
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subl2 r0,r2 # r2 = number of bytes to move
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subl2 r2,r1 # back up pointer updated by locc
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movc3 r2,(r1),(r3) # copy in last piece
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4: # null-pad logic
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movzwl $65535,r2 # r2 = bytes in first chunk
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cmpl r6,r2 # r2 = min(bytes in chunk, n);
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jgeq 5f
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movl r6,r2
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5:
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subl2 r2,r6 # update n
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movc5 $0,(r3),$0,r2,(r3)# pad with '\0's
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tstl r6 # finished padding?
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jneq 4b
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done:
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movl 4(ap),r0 # return s1
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ret
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