/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2008 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ .file "strncpy.s" /* * strncpy(s1, s2) * * Copy string s2 to s1, truncating or null-padding to always copy n bytes * return s1. * * Fast assembler language version of the following C-program for strncpy * which represents the `standard' for the C-library. * * char * * strncpy(char *s1, const char *s2, size_t n) * { * char *os1 = s1; * * n++; * while ((--n != 0) && ((*s1++ = *s2++) != '\0')) * ; * if (n != 0) * while (--n != 0) * *s1++ = '\0'; * return (os1); * } */ #include ! strncpy works similarly to strcpy, except that n bytes of s2 ! are copied to s1. If a null character is reached in s2 yet more ! bytes remain to be copied, strncpy will copy null bytes into ! the destination string. ! ! This implementation works by first aligning the src ptr and ! performing small copies until it is aligned. Then, the string ! is copied based upon destination alignment. (byte, half-word, ! word, etc.) ENTRY(strncpy) .align 32 nop ! pad to align loop on 16-byte boundary subcc %g0, %o2, %g4 ! n = -n, n == 0 ? bz,pn %ncc, .done ! n == 0, done add %o1, %o2, %o3 ! src = src + n andcc %o1, 7, %o4 ! dword aligned ? bz,pn %ncc, .dwordaligned ! yup add %o0, %o2, %o2 ! dst = dst + n sub %o4, 8, %o4 ! bytes until src aligned .alignsrc: ldub [%o3 + %g4], %o1 ! src[] stb %o1, [%o2 + %g4] ! dst[] = src[] addcc %g4, 1, %g4 ! src++, dst++, n-- bz,pn %ncc, .done ! n == 0, done tst %o1 ! end of src reached (null byte) ? bz,a %ncc, .bytepad ! yes, at least one byte to pad here add %o2, %g4, %o3 ! need single dest pointer for fill addcc %o4, 1, %o4 ! src aligned now? bnz,a %ncc, .alignsrc ! no, copy another byte nop ! pad nop ! pad .dwordaligned: sethi %hi(0x01010101), %o4 ! Alan Mycroft's magic1 add %o2, %g4, %g5 ! dst or %o4, %lo(0x01010101),%o4! finish loading magic1 and %g5, 3, %g1 ! dst<1:0> to examine offset sllx %o4, 32, %o1 ! spread magic1 cmp %g1, 1 ! dst offset of 1 or 5 or %o4, %o1, %o4 ! to all 64 bits sub %o2, 8, %o2 ! adjust for dest pre-incr in cpy loops be,pn %ncc, .storebyte1241 ! store 1, 2, 4, 1 bytes sllx %o4, 7, %o5 ! Alan Mycroft's magic2 cmp %g1, 3 ! dst offset of 3 or 7 be,pn %ncc, .storebyte1421 ! store 1, 4, 2, 1 bytes cmp %g1, 2 ! dst halfword aligned ? be,pn %ncc, .storehalfword ! yup, store half-word wise andcc %g5, 7, %g0 ! dst word aligned ? bnz,pn %ncc, .storeword2 ! yup, store word wise nop ! ensure loop is 16-byte aligned .storedword: ldx [%o3 + %g4], %o1 ! src dword addcc %g4, 8, %g4 ! n += 8, src += 8, dst += 8 bcs,pn %ncc,.lastword ! if counter wraps, last word andn %o5, %o1, %g1 ! ~dword & 0x8080808080808080 sub %o1, %o4, %g5 ! dword - 0x0101010101010101 andcc %g5, %g1, %g0 ! ((dword - 0x0101010101010101) & ~dword & 0x8080808080808080) bz,a,pt %ncc, .storedword ! no zero byte if magic expression == 0 stx %o1, [%o2 + %g4] ! store word to dst (address pre-incremented) ! n has not expired, but src is at the end. we need to push out the ! remaining src bytes and then start padding with null bytes .zerobyte: add %o2, %g4, %o3 ! pointer to dest string srlx %o1, 56, %g1 ! first byte stb %g1, [%o3] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 48, %g1 ! second byte stb %g1, [%o3 + 1] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 40, %g1 ! third byte stb %g1, [%o3 + 2] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 32, %g1 ! fourth byte stb %g1, [%o3 + 3] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 24, %g1 ! fifth byte stb %g1, [%o3 + 4] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 16, %g1 ! sixth byte stb %g1, [%o3 + 5] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 8, %g1 ! seventh byte stb %g1, [%o3 + 6] ! store it andcc %g1, 0xff, %g0 ! end of string ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes stb %o1, [%o3 + 7] ! store eighth byte addcc %g4, 16, %g0 ! number of pad bytes < 16 ? bcs,pn %ncc, .bytepad ! yes, do simple byte wise fill add %o3, 8, %o3 ! dst += 8 andcc %o3, 7, %o4 ! dst offset relative to dword boundary bz,pn %ncc, .fillaligned ! dst already dword aligned ! here there is a least one more byte to zero out: otherwise we would ! have exited through label .lastword sub %o4, 8, %o4 ! bytes to align dst to dword boundary .makealigned: stb %g0, [%o3] ! dst[] = 0 addcc %g4, 1, %g4 ! n-- bz,pt %ncc, .done ! n == 0, we are done addcc %o4, 1, %o4 ! any more byte needed to align bnz,pt %ncc, .makealigned ! yup, pad another byte add %o3, 1, %o3 ! dst++ nop ! pad to align copy loop below nop ! pad to align copy loop below ! here we know that there at least another 8 bytes to pad, since ! we don't get here unless there were >= 16 bytes to pad to begin ! with, and we have padded at most 7 bytes suring dst aligning .fillaligned: add %g4, 7, %o2 ! round up to next dword boundary and %o2, -8, %o4 ! pointer to next dword boundary and %o2, 8, %o2 ! dword count odd ? 8 : 0 stx %g0, [%o3] ! store first dword addcc %o4, %o2, %o4 ! dword count == 1 ? add %g4, %o2, %g4 ! if dword count odd, n -= 8 bz,pt %ncc, .bytepad ! if dword count == 1, pad leftover bytes add %o3, %o2, %o3 ! bump dst if dword count odd .filldword: addcc %o4, 16, %o4 ! count -= 16 stx %g0, [%o3] ! dst[n] = 0 stx %g0, [%o3 + 8] ! dst[n+8] = 0 add %o3, 16, %o3 ! dst += 16 bcc,pt %ncc, .filldword ! fill dwords until count == 0 addcc %g4, 16, %g4 ! n -= 16 bz,pn %ncc, .done ! if n == 0, we are done .bytepad: and %g4, 1, %o2 ! byte count odd ? 1 : 0 stb %g0, [%o3] ! store first byte addcc %g4, %o2, %g4 ! byte count == 1 ? bz,pt %ncc, .done ! yup, we are done add %o3, %o2, %o3 ! bump pointer if odd .fillbyte: addcc %g4, 2, %g4 ! n -= 2 stb %g0, [%o3] ! dst[n] = 0 stb %g0, [%o3 + 1] ! dst[n+1] = 0 bnz,pt %ncc, .fillbyte ! fill until n == 0 add %o3, 2, %o3 ! dst += 2 .done: retl ! done nop ! pad to align loops below nop ! pad to align loops below ! this is the last word. It may contain null bytes. store bytes ! until n == 0. if null byte encountered, continue .lastword: sub %g4, 8, %g4 ! undo counter pre-increment add %o2, 8, %o2 ! adjust dst for counter un-bumping srlx %o1, 56, %g1 ! first byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 48, %g1 ! second byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 40, %g1 ! third byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 32, %g1 ! fourth byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 24, %g1 ! fifth byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 16, %g1 ! sixth byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes srlx %o1, 8, %g1 ! seventh byte stb %g1, [%o2 + %g4] ! store it inccc %g4 ! n-- bz .done ! if n == 0, we're done andcc %g1, 0xff, %g0 ! end of src reached ? movz %ncc, %g0, %o1 ! if so, start padding with null bytes ba .done ! here n must be zero, we are done stb %o1, [%o2 + %g4] ! store eigth byte nop ! pad to align loops below nop ! pad to align loops below .storebyte1421: ldx [%o3 + %g4], %o1 ! x = src[] addcc %g4, 8, %g4 ! src += 8, dst += 8 bcs,pn %ncc,.lastword ! if counter wraps, last word andn %o5, %o1, %g1 ! ~x & 0x8080808080808080 sub %o1, %o4, %g5 ! x - 0x0101010101010101 andcc %g5, %g1, %g0 ! ((x - 0x0101010101010101) & ~x & 0x8080808080808080) bnz,pn %ncc, .zerobyte ! end of src found, may need to pad add %o2, %g4, %g5 ! dst (in pointer form) srlx %o1, 56, %g1 ! %g1<7:0> = first byte; word aligned now stb %g1, [%g5] ! store first byte srlx %o1, 24, %g1 ! %g1<31:0> = bytes 2, 3, 4, 5 stw %g1, [%g5 + 1] ! store bytes 2, 3, 4, 5 srlx %o1, 8, %g1 ! %g1<15:0> = bytes 6, 7 sth %g1, [%g5 + 5] ! store bytes 6, 7 ba .storebyte1421 ! next dword stb %o1, [%g5 + 7] ! store eigth byte .storebyte1241: ldx [%o3 + %g4], %o1 ! x = src[] addcc %g4, 8, %g4 ! src += 8, dst += 8 bcs,pn %ncc,.lastword ! if counter wraps, last word andn %o5, %o1, %g1 ! ~x & 0x8080808080808080 sub %o1, %o4, %g5 ! x - 0x0101010101010101 andcc %g5, %g1, %g0 ! ((x - 0x0101010101010101) & ~x & 0x8080808080808080) bnz,pn %ncc, .zerobyte ! x has zero byte, handle end cases add %o2, %g4, %g5 ! dst (in pointer form) srlx %o1, 56, %g1 ! %g1<7:0> = first byte; half-word aligned now stb %g1, [%g5] ! store first byte srlx %o1, 40, %g1 ! %g1<15:0> = bytes 2, 3 sth %g1, [%g5 + 1] ! store bytes 2, 3 srlx %o1, 8, %g1 ! %g1<31:0> = bytes 4, 5, 6, 7 stw %g1, [%g5 + 3] ! store bytes 4, 5, 6, 7 ba .storebyte1241 ! next dword stb %o1, [%g5 + 7] ! store eigth byte .storehalfword: ldx [%o3 + %g4], %o1 ! x = src[] addcc %g4, 8, %g4 ! src += 8, dst += 8 bcs,pn %ncc,.lastword ! if counter wraps, last word andn %o5, %o1, %g1 ! ~x & 0x8080808080808080 sub %o1, %o4, %g5 ! x - 0x0101010101010101 andcc %g5, %g1, %g0 ! ((x - 0x0101010101010101) & ~x & 0x8080808080808080) bnz,pn %ncc, .zerobyte ! x has zero byte, handle end cases add %o2, %g4, %g5 ! dst (in pointer form) srlx %o1, 48, %g1 ! %g1<15:0> = bytes 1, 2; word aligned now sth %g1, [%g5] ! store bytes 1, 2 srlx %o1, 16, %g1 ! %g1<31:0> = bytes 3, 4, 5, 6 stw %g1, [%g5 + 2] ! store bytes 3, 4, 5, 6 ba .storehalfword ! next dword sth %o1, [%g5 + 6] ! store bytes 7, 8 nop ! align next loop to 16-byte boundary nop ! align next loop to 16-byte boundary .storeword2: ldx [%o3 + %g4], %o1 ! x = src[] addcc %g4, 8, %g4 ! src += 8, dst += 8 bcs,pn %ncc,.lastword ! if counter wraps, last word andn %o5, %o1, %g1 ! ~x & 0x8080808080808080 sub %o1, %o4, %g5 ! x - 0x0101010101010101 andcc %g5, %g1, %g0 ! ((x - 0x0101010101010101) & ~x & 0x8080808080808080) bnz,pn %ncc, .zerobyte ! x has zero byte, handle end cases add %o2, %g4, %g5 ! dst (in pointer form) srlx %o1, 32, %g1 ! %g1<31:0> = bytes 1, 2, 3, 4 stw %g1, [%g5] ! store bytes 1, 2, 3, 4 ba .storeword2 ! next dword stw %o1, [%g5 + 4] ! store bytes 5, 6, 7, 8 ! do not remove these pads, loop above may slow down otherwise nop ! pad nop ! pad SET_SIZE(strncpy)