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9b20c629fe
Add assembly-optimized implementations for 14 string/memory functions using word-at-a-time techniques (DETECTNULL, broadcast+XOR) and XLEN-adaptive macros for both RV32 and RV64: - memmove: direction check + forward tail to memcpy, reverse path with 16xSZREG unroll and shift-merge for misaligned src. - memcmp: word-granularity compare when both pointers share alignment, bytewise fallback for mismatched pointers. - memchr: broadcast target byte, XOR with each word, DETECTNULL to find matches. Counter-based bounds (no pointer overflow). - strlen: DETECTNULL word loop, constants loaded from .srodata. - strnlen: strlen with counter-based length limit. - strcpy/strncpy: word loop with DETECTNULL, zero-fill remainder for strncpy. strncpy reuses strcpy via #define USE_AS_STRNCPY. - stpcpy/stpncpy: reuse strcpy/strncpy via #define USE_AS_STPCPY. - strchr/strchrnul: broadcast+XOR detecting both target char and null simultaneously. strchrnul reuses strchr via #define. - strrchr: forward scan recording last match position. - strncmp: word-at-a-time compare with null detection and counter. - strcat: strlen(dst) then strcpy(dst_end, src) word-at-a-time. Each function is independently selectable via CONFIG_RISCV_<FUNC>, or all enabled together with CONFIG_RISCV_STRING_FUNCTION=y. Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com> Signed-off-by: ganjing <ganjing@xiaomi.com>
117 lines
2.5 KiB
ArmAsm
117 lines
2.5 KiB
ArmAsm
/****************************************************************************
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* libs/libc/machine/risc-v/arch_strlen.S
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#include "libc.h"
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#ifdef LIBC_BUILD_STRLEN
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#include "asm.h"
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.text
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.global ARCH_LIBCFUN(strlen)
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.type ARCH_LIBCFUN(strlen), @function
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.align 2
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/************************************************************************************
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* Name: strlen
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*
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* size_t strlen(const char *s)
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*
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* Word-at-a-time DETECTNULL scanning.
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************************************************************************************/
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ARCH_LIBCFUN(strlen):
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.cfi_sections .debug_frame
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.cfi_startproc
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mv t0, a0
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.Lbyte_head:
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andi t1, t0, SZREG-1
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beqz t1, .Laligned
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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j .Lbyte_head
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.Laligned:
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#if SZREG == 8
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lla t3, .Lmask01
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ld t3, 0(t3)
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lla t4, .Lmask80
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ld t4, 0(t4)
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#else
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li t3, 0x01010101
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li t4, 0x80808080
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#endif
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.Lword_loop:
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REG_L t1, 0(t0)
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sub t2, t1, t3
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not t5, t1
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and t2, t2, t5
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and t2, t2, t4
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bnez t2, .Lfind_null
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addi t0, t0, SZREG
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j .Lword_loop
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.Lfind_null:
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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#if SZREG == 8
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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lbu t2, 0(t0)
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beqz t2, .Ldone
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addi t0, t0, 1
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#endif
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.Ldone:
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sub a0, t0, a0
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ret
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.cfi_endproc
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.size ARCH_LIBCFUN(strlen), .-ARCH_LIBCFUN(strlen)
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#if SZREG == 8
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.section .srodata.cst8,"aM",@progbits,8
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.align 3
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.Lmask01:
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.dword 0x0101010101010101
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.Lmask80:
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.dword 0x8080808080808080
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#endif
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#endif
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