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Diffstat (limited to 'newlib/libc/machine/aarch64/strnlen.S')
| -rw-r--r-- | newlib/libc/machine/aarch64/strnlen.S | 187 |
1 files changed, 0 insertions, 187 deletions
diff --git a/newlib/libc/machine/aarch64/strnlen.S b/newlib/libc/machine/aarch64/strnlen.S deleted file mode 100644 index c255c3f7c..000000000 --- a/newlib/libc/machine/aarch64/strnlen.S +++ /dev/null @@ -1,187 +0,0 @@ -/* strnlen - calculate the length of a string with limit. - - Copyright (c) 2013, 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. */ - -#if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED)) -/* See strlen-stub.c */ -#else - -/* Assumptions: - * - * ARMv8-a, AArch64 - */ - -/* Arguments and results. */ -#define srcin x0 -#define len x0 -#define limit x1 - -/* Locals and temporaries. */ -#define src x2 -#define data1 x3 -#define data2 x4 -#define data2a x5 -#define has_nul1 x6 -#define has_nul2 x7 -#define tmp1 x8 -#define tmp2 x9 -#define tmp3 x10 -#define tmp4 x11 -#define zeroones x12 -#define pos x13 -#define limit_wd x14 - - .macro def_fn f p2align=0 - .text - .p2align \p2align - .global \f - .type \f, %function -\f: - .endm - -#define REP8_01 0x0101010101010101 -#define REP8_7f 0x7f7f7f7f7f7f7f7f -#define REP8_80 0x8080808080808080 - - .text - .p2align 6 -.Lstart: - /* Pre-pad to ensure critical loop begins an icache line. */ - .rep 7 - nop - .endr - /* Put this code here to avoid wasting more space with pre-padding. */ -.Lhit_limit: - mov len, limit - ret - -def_fn strnlen - cbz limit, .Lhit_limit - mov zeroones, #REP8_01 - bic src, srcin, #15 - ands tmp1, srcin, #15 - b.ne .Lmisaligned - /* Calculate the number of full and partial words -1. */ - sub limit_wd, limit, #1 /* Limit != 0, so no underflow. */ - lsr limit_wd, limit_wd, #4 /* Convert to Qwords. */ - - /* 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. */ - - /* Start of critial section -- keep to one 64Byte cache line. */ -.Lloop: - ldp data1, data2, [src], #16 -.Lrealigned: - sub tmp1, data1, zeroones - orr tmp2, data1, #REP8_7f - sub tmp3, data2, zeroones - orr tmp4, data2, #REP8_7f - bic has_nul1, tmp1, tmp2 - bic has_nul2, tmp3, tmp4 - subs limit_wd, limit_wd, #1 - orr tmp1, has_nul1, has_nul2 - ccmp tmp1, #0, #0, pl /* NZCV = 0000 */ - b.eq .Lloop - /* End of critical section -- keep to one 64Byte cache line. */ - - orr tmp1, has_nul1, has_nul2 - cbz tmp1, .Lhit_limit /* No null in final Qword. */ - - /* We know there's a null in the final Qword. The easiest thing - to do now is work out the length of the string and return - MIN (len, limit). */ - - sub len, src, srcin - cbz has_nul1, .Lnul_in_data2 -#ifdef __AARCH64EB__ - mov data2, data1 -#endif - sub len, len, #8 - mov has_nul2, has_nul1 -.Lnul_in_data2: -#ifdef __AARCH64EB__ - /* For big-endian, carry propagation (if the final byte in the - string is 0x01) means we cannot use has_nul directly. The - easiest way to get the correct byte is to byte-swap the data - and calculate the syndrome a second time. */ - rev data2, data2 - sub tmp1, data2, zeroones - orr tmp2, data2, #REP8_7f - bic has_nul2, tmp1, tmp2 -#endif - sub len, len, #8 - rev has_nul2, has_nul2 - clz pos, has_nul2 - add len, len, pos, lsr #3 /* Bits to bytes. */ - cmp len, limit - csel len, len, limit, ls /* Return the lower value. */ - ret - -.Lmisaligned: - /* Deal with a partial first word. - We're doing two things in parallel here; - 1) Calculate the number of words (but avoiding overflow if - limit is near ULONG_MAX) - to do this we need to work out - limit + tmp1 - 1 as a 65-bit value before shifting it; - 2) Load and mask the initial data words - we force the bytes - before the ones we are interested in to 0xff - this ensures - early bytes will not hit any zero detection. */ - sub limit_wd, limit, #1 - neg tmp4, tmp1 - cmp tmp1, #8 - - and tmp3, limit_wd, #15 - lsr limit_wd, limit_wd, #4 - mov tmp2, #~0 - - ldp data1, data2, [src], #16 - lsl tmp4, tmp4, #3 /* Bytes beyond alignment -> bits. */ - add tmp3, tmp3, tmp1 - -#ifdef __AARCH64EB__ - /* Big-endian. Early bytes are at MSB. */ - lsl tmp2, tmp2, tmp4 /* Shift (tmp1 & 63). */ -#else - /* Little-endian. Early bytes are at LSB. */ - lsr tmp2, tmp2, tmp4 /* Shift (tmp1 & 63). */ -#endif - add limit_wd, limit_wd, tmp3, lsr #4 - - orr data1, data1, tmp2 - orr data2a, data2, tmp2 - - csinv data1, data1, xzr, le - csel data2, data2, data2a, le - b .Lrealigned - .size strnlen, . - .Lstart /* Include pre-padding in size. */ - -#endif |