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Diffstat (limited to 'libc/string/xtensa/strncpy.S')
| -rw-r--r-- | libc/string/xtensa/strncpy.S | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/libc/string/xtensa/strncpy.S b/libc/string/xtensa/strncpy.S new file mode 100644 index 000000000..7ba2ef77d --- /dev/null +++ b/libc/string/xtensa/strncpy.S @@ -0,0 +1,241 @@ +/* Optimized strcpy for Xtensa. + Copyright (C) 2001, 2007 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 51 Franklin Street - Fifth Floor, + Boston, MA 02110-1301, USA. */ + +#include "../../sysdeps/linux/xtensa/sysdep.h" +#include <bits/xtensa-config.h> + +#ifdef __XTENSA_EB__ +#define MASK0 0xff000000 +#define MASK1 0x00ff0000 +#define MASK2 0x0000ff00 +#define MASK3 0x000000ff +#else +#define MASK0 0x000000ff +#define MASK1 0x0000ff00 +#define MASK2 0x00ff0000 +#define MASK3 0xff000000 +#endif + +/* Do not use .literal_position in the ENTRY macro. */ +#undef LITERAL_POSITION +#define LITERAL_POSITION + + .text + .align 4 + .literal_position +__strncpy_aux: + +.Lsrc1mod2: // src address is odd + l8ui a8, a3, 0 // get byte 0 + addi a3, a3, 1 // advance src pointer + s8i a8, a10, 0 // store byte 0 + addi a4, a4, -1 // decrement n + beqz a4, .Lret // if n is zero + addi a10, a10, 1 // advance dst pointer + beqz a8, .Lfill // if byte 0 is zero + bbci.l a3, 1, .Lsrcaligned // if src is now word-aligned + +.Lsrc2mod4: // src address is 2 mod 4 + l8ui a8, a3, 0 // get byte 0 + addi a4, a4, -1 // decrement n + s8i a8, a10, 0 // store byte 0 + beqz a4, .Lret // if n is zero + addi a10, a10, 1 // advance dst pointer + beqz a8, .Lfill // if byte 0 is zero + l8ui a8, a3, 1 // get byte 0 + addi a3, a3, 2 // advance src pointer + s8i a8, a10, 0 // store byte 0 + addi a4, a4, -1 // decrement n + beqz a4, .Lret // if n is zero + addi a10, a10, 1 // advance dst pointer + bnez a8, .Lsrcaligned + j .Lfill + +.Lret: + retw + + +ENTRY (strncpy) + /* a2 = dst, a3 = src */ + + mov a10, a2 // leave dst in return value register + beqz a4, .Lret // if n is zero + + movi a11, MASK0 + movi a5, MASK1 + movi a6, MASK2 + movi a7, MASK3 + bbsi.l a3, 0, .Lsrc1mod2 + bbsi.l a3, 1, .Lsrc2mod4 +.Lsrcaligned: + + /* Check if the destination is aligned. */ + movi a8, 3 + bnone a10, a8, .Laligned + + j .Ldstunaligned + + +/* Fill the dst with zeros -- n is at least 1. */ + +.Lfill: + movi a9, 0 + bbsi.l a10, 0, .Lfill1mod2 + bbsi.l a10, 1, .Lfill2mod4 +.Lfillaligned: + blti a4, 4, .Lfillcleanup + + /* Loop filling complete words with zero. */ +#if XCHAL_HAVE_LOOPS + + srai a8, a4, 2 + loop a8, 1f + s32i a9, a10, 0 + addi a10, a10, 4 + +1: slli a8, a8, 2 + sub a4, a4, a8 + +#else /* !XCHAL_HAVE_LOOPS */ + +1: s32i a9, a10, 0 + addi a10, a10, 4 + addi a4, a4, -4 + bgei a4, 4, 1b + +#endif /* !XCHAL_HAVE_LOOPS */ + + beqz a4, 2f + +.Lfillcleanup: + /* Fill leftover (1 to 3) bytes with zero. */ + s8i a9, a10, 0 // store byte 0 + addi a4, a4, -1 // decrement n + addi a10, a10, 1 + bnez a4, .Lfillcleanup + +2: retw + +.Lfill1mod2: // dst address is odd + s8i a9, a10, 0 // store byte 0 + addi a4, a4, -1 // decrement n + beqz a4, 2b // if n is zero + addi a10, a10, 1 // advance dst pointer + bbci.l a10, 1, .Lfillaligned // if dst is now word-aligned + +.Lfill2mod4: // dst address is 2 mod 4 + s8i a9, a10, 0 // store byte 0 + addi a4, a4, -1 // decrement n + beqz a4, 2b // if n is zero + s8i a9, a10, 1 // store byte 1 + addi a4, a4, -1 // decrement n + beqz a4, 2b // if n is zero + addi a10, a10, 2 // advance dst pointer + j .Lfillaligned + + +/* dst is word-aligned; src is word-aligned; n is at least 1. */ + + .align 4 + /* (2 mod 4) alignment for loop instruction */ +.Laligned: +#if XCHAL_HAVE_LOOPS + _movi.n a8, 0 // set up for the maximum loop count + loop a8, 1f // loop forever (almost anyway) + blti a4, 5, .Ldstunaligned // n is near limit; do one at a time + l32i a8, a3, 0 // get word from src + addi a3, a3, 4 // advance src pointer + bnone a8, a11, .Lz0 // if byte 0 is zero + bnone a8, a5, .Lz1 // if byte 1 is zero + bnone a8, a6, .Lz2 // if byte 2 is zero + s32i a8, a10, 0 // store word to dst + addi a4, a4, -4 // decrement n + addi a10, a10, 4 // advance dst pointer + bnone a8, a7, .Lfill // if byte 3 is zero +1: + +#else /* !XCHAL_HAVE_LOOPS */ + +1: blti a4, 5, .Ldstunaligned // n is near limit; do one at a time + l32i a8, a3, 0 // get word from src + addi a3, a3, 4 // advance src pointer + bnone a8, a11, .Lz0 // if byte 0 is zero + bnone a8, a5, .Lz1 // if byte 1 is zero + bnone a8, a6, .Lz2 // if byte 2 is zero + s32i a8, a10, 0 // store word to dst + addi a4, a4, -4 // decrement n + addi a10, a10, 4 // advance dst pointer + bany a8, a7, 1b // no zeroes +#endif /* !XCHAL_HAVE_LOOPS */ + + j .Lfill + +.Lz0: /* Byte 0 is zero. */ +#ifdef __XTENSA_EB__ + movi a8, 0 +#endif + s8i a8, a10, 0 + addi a4, a4, -1 // decrement n + addi a10, a10, 1 // advance dst pointer + j .Lfill + +.Lz1: /* Byte 1 is zero. */ +#ifdef __XTENSA_EB__ + extui a8, a8, 16, 16 +#endif + s16i a8, a10, 0 + addi a4, a4, -2 // decrement n + addi a10, a10, 2 // advance dst pointer + j .Lfill + +.Lz2: /* Byte 2 is zero. */ +#ifdef __XTENSA_EB__ + extui a8, a8, 16, 16 +#endif + s16i a8, a10, 0 + movi a8, 0 + s8i a8, a10, 2 + addi a4, a4, -3 // decrement n + addi a10, a10, 3 // advance dst pointer + j .Lfill + + .align 4 + /* (2 mod 4) alignment for loop instruction */ +.Ldstunaligned: + +#if XCHAL_HAVE_LOOPS + _movi.n a8, 0 // set up for the maximum loop count + loop a8, 2f // loop forever (almost anyway) +#endif +1: l8ui a8, a3, 0 + addi a3, a3, 1 + s8i a8, a10, 0 + addi a4, a4, -1 + beqz a4, 3f + addi a10, a10, 1 +#if XCHAL_HAVE_LOOPS + beqz a8, 2f +#else + bnez a8, 1b +#endif +2: j .Lfill + +3: retw + +libc_hidden_def (strncpy) |