我正在使用 c 内在函数处理 ARM neon 代码。当我编译文件时，我不断收到以下错误：
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/bin/ld.exe：警告：找不到入口符号_start；默认为 00008020
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-exit.o)：在函数“exit”中：exit.c:(.text+0x28)：未定义对“_exit”的引用
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-fstatr.o)：在函数“_fst at_r”中：fstatr.c:(.text+0x1c)：未定义对“_fstat”的引用
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-openr.o)：在函数“_open _r”中：openr.c:(.text+0x20)：未定义对“_open”的引用
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-sbrkr.o)：在函数'_sbrk _r'中：sbrkr.c:(.text+0x18)：未定义引用'_sbrk'
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-writer.o): 在函数'_write_r':writer.c:(.text+0x20): 未定义引用'_write'
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-closer.o)：在函数“_close_r”中：closer.c:(.text+0x18)：未定义对“_close”的引用
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-isattyr.o): 在函数'_is atty_r':isattyr.c:(.text+0x18): 未定义引用'_isatty'
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-lseekr.o): 在函数 '_lse ek_r':lseekr.c:(.text+0x20): 未定义引用'_lseek'
c:/program files (x86)/codesourcery/sourcery g++ lite/bin/../lib/gcc/arm-none-ea bi/4.3.3/../../../../arm-none -eabi/lib\libc.a(lib_a-readr.o): 在函数 '_read _r':readr.c:(.text+0x20): 未定义引用 '_read'
collect2: ld 返回 1 个退出状态
谁能告诉我如何纠正这些错误？我所知道的是我必须明确定义函数isatty()等fstat。但我不知道在哪里定义它们