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Diffstat (limited to 'libc/arch-arm64/generic/bionic/string_copy.S')
| -rw-r--r-- | libc/arch-arm64/generic/bionic/string_copy.S | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/libc/arch-arm64/generic/bionic/string_copy.S b/libc/arch-arm64/generic/bionic/string_copy.S new file mode 100644 index 000000000..2bf969d60 --- /dev/null +++ b/libc/arch-arm64/generic/bionic/string_copy.S @@ -0,0 +1,245 @@ +/* + * Copyright (C) 2014 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* + Copyright (c) 2014, Linaro Limited + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions are met: + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in the + documentation and/or other materials provided with the distribution. + * Neither the name of the Linaro nor the + names of its contributors may be used to endorse or promote products + derived from this software without specific prior written permission. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ + +/* Assumptions: + * + * ARMv8-a, AArch64 + */ + +#if !defined(STPCPY) && !defined(STRCPY) +#error "Either STPCPY or STRCPY must be defined." +#endif + +#include <private/bionic_asm.h> + +/* Arguments and results. */ +#if defined(STPCPY) +#define dst x0 +#elif defined(STRCPY) +#define dstin x0 +#endif +#define src x1 + +/* Locals and temporaries. */ +#if defined(STRCPY) +#define dst x2 +#endif +#define data1 x3 +#define data1_w w3 +#define data2 x4 +#define data2_w w4 +#define has_nul1 x5 +#define has_nul1_w w5 +#define has_nul2 x6 +#define tmp1 x7 +#define tmp2 x8 +#define tmp3 x9 +#define tmp4 x10 +#define zeroones x11 +#define zeroones_w w11 +#define pos x12 + +#define REP8_01 0x0101010101010101 +#define REP8_7f 0x7f7f7f7f7f7f7f7f +#define REP8_80 0x8080808080808080 + +#if defined(STPCPY) +ENTRY(stpcpy) +#elif defined(STRCPY) +ENTRY(strcpy) +#endif + mov zeroones, #REP8_01 +#if defined(STRCPY) + mov dst, dstin +#endif + ands tmp1, src, #15 + b.ne .Lmisaligned + // NUL detection works on the principle that (X - 1) & (~X) & 0x80 + // (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and + // can be done in parallel across the entire word. + // The inner loop deals with two Dwords at a time. This has a + // slightly higher start-up cost, but we should win quite quickly, + // especially on cores with a high number of issue slots per + // cycle, as we get much better parallelism out of the operations. +.Lloop: + ldp data1, data2, [src], #16 + sub tmp1, data1, zeroones + orr tmp2, data1, #REP8_7f + bic has_nul1, tmp1, tmp2 + cbnz has_nul1, .Lnul_in_data1 + sub tmp3, data2, zeroones + orr tmp4, data2, #REP8_7f + bic has_nul2, tmp3, tmp4 + cbnz has_nul2, .Lnul_in_data2 + // No NUL in either register, copy it in a single instruction. + stp data1, data2, [dst], #16 + b .Lloop + +.Lnul_in_data1: + rev has_nul1, has_nul1 + clz pos, has_nul1 + add tmp1, pos, #0x8 + + tbz tmp1, #6, 1f +#if defined(STPCPY) + str data1, [dst], #7 +#elif defined(STRCPY) + str data1, [dst] +#endif + ret +1: + tbz tmp1, #5, 1f + str data1_w, [dst], #4 + lsr data1, data1, #32 +1: + tbz tmp1, #4, 1f + strh data1_w, [dst], #2 + lsr data1, data1, #16 +1: + tbz tmp1, #3, 1f + strb data1_w, [dst] +#if defined(STPCPY) + ret +#endif +1: +#if defined(STPCPY) + // Back up one so that dst points to the '\0' string terminator. + sub dst, dst, #1 +#endif + ret + +.Lnul_in_data2: + str data1, [dst], #8 + rev has_nul2, has_nul2 + clz pos, has_nul2 + add tmp1, pos, #0x8 + + tbz tmp1, #6, 1f +#if defined(STPCPY) + str data2, [dst], #7 +#elif defined(STRCPY) + str data2, [dst] +#endif + ret +1: + tbz tmp1, #5, 1f + str data2_w, [dst], #4 + lsr data2, data2, #32 +1: + tbz tmp1, #4, 1f + strh data2_w, [dst], #2 + lsr data2, data2, #16 +1: + tbz tmp1, #3, 1f + strb data2_w, [dst] +#if defined(STPCPY) + ret +#endif +1: +#if defined(STPCPY) + // Back up one so that dst points to the '\0' string terminator. + sub dst, dst, #1 +#endif + ret + +.Lmisaligned: + tbz src, #0, 1f + ldrb data1_w, [src], #1 + strb data1_w, [dst], #1 + cbnz data1_w, 1f +#if defined(STPCPY) + // Back up one so that dst points to the '\0' string terminator. + sub dst, dst, #1 +#endif + ret +1: + tbz src, #1, 1f + ldrb data1_w, [src], #1 + strb data1_w, [dst], #1 + cbz data1_w, .Ldone + ldrb data2_w, [src], #1 + strb data2_w, [dst], #1 + cbnz data2_w, 1f +.Ldone: +#if defined(STPCPY) + // Back up one so that dst points to the '\0' string terminator. + sub dst, dst, #1 +#endif + ret +1: + tbz src, #2, 1f + ldr data1_w, [src], #4 + // Check for a zero. + sub has_nul1_w, data1_w, zeroones_w + bic has_nul1_w, has_nul1_w, data1_w + ands has_nul1_w, has_nul1_w, #0x80808080 + b.ne .Lnul_in_data1 + str data1_w, [dst], #4 +1: + tbz src, #3, .Lloop + ldr data1, [src], #8 + // Check for a zero. + sub tmp1, data1, zeroones + orr tmp2, data1, #REP8_7f + bics has_nul1, tmp1, tmp2 + b.ne .Lnul_in_data1 + str data1, [dst], #8 + b .Lloop +#if defined(STPCPY) +END(stpcpy) +#elif defined(STRCPY) +END(strcpy) +#endif |