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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>
171 lines
3.5 KiB
ArmAsm
171 lines
3.5 KiB
ArmAsm
/****************************************************************************
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* libs/libc/machine/risc-v/arch_strchr.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_STRCHR
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#include "asm.h"
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#ifndef STRCHR
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#define STRCHR ARCH_LIBCFUN(strchr)
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#endif
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.text
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.global STRCHR
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.type STRCHR, @function
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.align 2
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/************************************************************************************
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* Name: strchr
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*
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* char *strchr(const char *s, int c)
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*
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* Broadcast + DETECTCHAR + DETECTNULL. Supports strchrnul via macro.
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************************************************************************************/
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STRCHR:
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.cfi_sections .debug_frame
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.cfi_startproc
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andi a1, a1, 0xff
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/* Byte-by-byte until aligned */
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.Lalign_loop:
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andi t0, a0, SZREG-1
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beqz t0, .Laligned
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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j .Lalign_loop
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.Laligned:
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/* Broadcast c to all bytes */
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slli t0, a1, 8
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or t0, t0, a1
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slli t1, t0, 16
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or a6, t0, t1 /* a6 = broadcast_c (32-bit) */
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#if SZREG == 8
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slli t0, a6, 32
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or a6, a6, t0 /* a6 = broadcast_c (64-bit) */
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#endif
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/* Load masks */
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#if SZREG == 8
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lla t2, .Lchr_mask01
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ld t2, 0(t2)
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lla t3, .Lchr_mask80
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ld t3, 0(t3)
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#else
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li t2, 0x01010101
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li t3, 0x80808080
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#endif
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.Lword_loop:
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REG_L t0, 0(a0)
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/* DETECTNULL(word) - check for string end */
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sub t1, t0, t2
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not t4, t0
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and t1, t1, t4
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and t1, t1, t3
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/* DETECTCHAR(word, c) = DETECTNULL(word ^ broadcast_c) */
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xor t4, t0, a6
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sub t5, t4, t2
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not a5, t4
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and t5, t5, a5
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and t5, t5, t3
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/* If either null or char found */
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or a5, t1, t5
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bnez a5, .Lbyte_scan
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addi a0, a0, SZREG
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j .Lword_loop
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.Lbyte_scan:
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/* Scan byte-by-byte to determine if char or null came first */
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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#if SZREG == 8
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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lbu t1, 0(a0)
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beq t1, a1, .Lfound
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beqz t1, .Lnot_found
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addi a0, a0, 1
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#endif
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j .Lword_loop
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.Lfound:
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ret
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.Lnot_found:
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#ifdef USE_AS_STRCHRNUL
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ret
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#else
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li a0, 0
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ret
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#endif
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.cfi_endproc
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.size STRCHR, .-STRCHR
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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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.Lchr_mask01:
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.dword 0x0101010101010101
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.Lchr_mask80:
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.dword 0x8080808080808080
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#endif
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#endif
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