摘要:本文主要向大家介绍了C/C++知识点之002_helloworld.cpp,通过具体的内容向大家展示,希望对大家学习C/C++知识点有所帮助。
本文主要向大家介绍了C/C++知识点之002_helloworld.cpp,通过具体的内容向大家展示,希望对大家学习C/C++知识点有所帮助。
//库函数
void Memset(void *mem, unsigned char byte, unsigned int len);void _memcpy(void *, void *, unsigned int);int _printf(char *, ...);char * itoa(long, char *);char * itox(long, char *);int _puts(char *);int _puts_nl(char *);size_t _strlen(char *);int _strncmp(const char *, const char *, size_t);int _strcmp(const char *, const char *);int _memcmp(const void *, const void *, unsigned int);char _toupper(char c);void Memset(void *mem, unsigned char byte, unsigned int len){ unsigned char *p = (unsigned char *)mem; int i = len; while (i--) { *p = byte; p++; } }void _memcpy(void *dst, void *src, unsigned int len) { int i; unsigned char *s = (unsigned char *)src; unsigned char *d = (unsigned char *)dst; for (i = 0; i < len; i++) { *d = *s; s++, d++; } }int _printf(char *fmt, ...) { int in_p; unsigned long dword; unsigned int word; char numbuf[26] = {0}; __builtin_va_list alist; in_p; __builtin_va_start((alist), (fmt)); in_p = 0; while(*fmt) { if (*fmt!='%' && !in_p) { _write(1, fmt, 1); in_p = 0; } else if (*fmt!='%') { switch(*fmt) { case 's': dword = (unsigned long) __builtin_va_arg(alist, long); _puts((char *)dword); break; case 'u': word = (unsigned int) __builtin_va_arg(alist, int); _puts(itoa(word, numbuf)); break; case 'd': word = (unsigned int) __builtin_va_arg(alist, int); _puts(itoa(word, numbuf)); break; case 'x': dword = (unsigned long) __builtin_va_arg(alist, long); _puts(itox(dword, numbuf)); break; default: _write(1, fmt, 1); break; } in_p = 0; } else { in_p = 1; } fmt++; } return 1; }char * itoa(long x, char *t){ int i; int j; i = 0; do { t[i] = (x % 10) + '0'; x /= 10; i++; } while (x!=0); t[i] = 0; for (j=0; j < i / 2; j++) { t[j] ^= t[i - j - 1]; t[i - j - 1] ^= t[j]; t[j] ^= t[i - j - 1]; } return t; }char * itox(long x, char *t){ int i; int j; i = 0; do { t[i] = (x % 16); /* char conversion */ if (t[i] > 9) t[i] = (t[i] - 10) + 'a'; else t[i] += '0'; x /= 16; i++; } while (x != 0); t[i] = 0; for (j=0; j < i / 2; j++) { t[j] ^= t[i - j - 1]; t[i - j - 1] ^= t[j]; t[j] ^= t[i - j - 1]; } return t; }int _puts(char *str) { _write(1, str, _strlen(str)); _fsync(1); return 1; }int _puts_nl(char *str) { _write(1, str, _strlen(str)); _write(1, ""\n"", 1); _fsync(1); return 1; }size_t _strlen(char *s) { size_t sz; for (sz=0;s[sz];sz++); return sz; }int _strncmp(const char *s1, const char *s2, size_t n) { for ( ; n > 0; s1++, s2++, --n) if (*s1 != *s2) return ((*(unsigned char *)s1 < *(unsigned char *)s2) ? -1 : +1); else if (*s1 == '\0') return 0; return 0; }int _strcmp(const char *s1, const char *s2) { for ( ; *s1 == *s2; s1++, s2++) if (*s1 == '\0') return 0; return ((*(unsigned char *)s1 < *(unsigned char *)s2) ? -1 : +1); }int _memcmp(const void *s1, const void *s2, unsigned int n) { unsigned char u1, u2; for ( ; n-- ; s1++, s2++) { u1 = * (unsigned char *) s1; u2 = * (unsigned char *) s2; if ( u1 != u2) { return (u1-u2); } } }char _toupper(char c) { if( c >='a' && c <= 'z') return (c = c +'A' - 'a'); return c; }
//系统调用
int _getuid(void);int _unlink(const char *path);int _mprotect(void * addr, unsigned long len, int prot);int _puts(char *str);int _puts_nl(char *str);int _fsync(int fd);long _ptrace(long request, long pid, void *addr, void *data);int _prctl(long option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5);int _fstat(long, void *);long _lseek(long, long, unsigned int);void Exit(long);void *_mmap(void *, unsigned long, unsigned long, unsigned long, long, unsigned long);int _munmap(void *, size_t);long _open(const char *, unsigned long, long);long _write(long, char *, unsigned long);int _read(long, char *, unsigned long);int _getdents64(unsigned int fd, struct linux_dirent64 *dirp, unsigned int count);int _rename(const char *, const char *);int _close(unsigned int);int _gettimeofday(struct timeval *, struct timezone *);int _getuid(void) { unsigned long ret; __asm__ volatile(""mov $102, %rax\n"" ""syscall""); asm (""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }int _unlink(const char *path) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov $87, %%rax\n"" ""syscall"" ::""g""(path)); asm(""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }int _mprotect(void * addr, unsigned long len, int prot) { unsigned long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov $10, %%rax\n"" ""syscall"" : : ""g""(addr), ""g""(len), ""g""(prot)); asm(""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }int _puts(char *str) { _write(1, str, _strlen(str)); _fsync(1); return 1; }int _puts_nl(char *str) { _write(1, str, _strlen(str)); _write(1, ""\n"", 1); _fsync(1); return 1; }int _fsync(int fd) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov $74, %%rax\n"" ""syscall"" : : ""g""(fd)); asm (""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }long _ptrace(long request, long pid, void *addr, void *data) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov %3, %%r10\n"" ""mov $101, %%rax\n"" ""syscall"" : : ""g""(request), ""g""(pid), ""g""(addr), ""g""(data)); asm(""mov %%rax, %0"" : ""=r""(ret)); return ret; }int _prctl(long option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov %3, %%r10\n"" ""mov $157, %%rax\n"" ""syscall\n"" :: ""g""(option), ""g""(arg2), ""g""(arg3), ""g""(arg4), ""g""(arg5)); asm(""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }int _fstat(long fd, void *buf) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov $5, %%rax\n"" ""syscall"" : : ""g""(fd), ""g""(buf)); asm(""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }long _lseek(long fd, long offset, unsigned int whence) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov $8, %%rax\n"" ""syscall"" : : ""g""(fd), ""g""(offset), ""g""(whence)); asm(""mov %%rax, %0"" : ""=r""(ret)); return ret; }void Exit(long status) { __asm__ volatile(""mov %0, %%rdi\n"" ""mov $60, %%rax\n"" ""syscall"" : : ""r""(status)); }void *_mmap(void *addr, unsigned long len, unsigned long prot, unsigned long flags, long fd, unsigned long off) { long mmap_fd = fd; unsigned long mmap_off = off; unsigned long mmap_flags = flags; unsigned long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov %3, %%r10\n"" ""mov %4, %%r8\n"" ""mov %5, %%r9\n"" ""mov $9, %%rax\n"" ""syscall\n"" : : ""g""(addr), ""g""(len), ""g""(prot), ""g""(flags), ""g""(mmap_fd), ""g""(mmap_off)); asm (""mov %%rax, %0"" : ""=r""(ret)); return (void *)ret; }int _munmap(void *addr, size_t len) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov $11, %%rax\n"" ""syscall"" :: ""g""(addr), ""g""(len)); asm (""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }long _open(const char *path, unsigned long flags, long mode) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov $2, %%rax\n"" ""syscall"" : : ""g""(path), ""g""(flags), ""g""(mode)); asm (""mov %%rax, %0"" : ""=r""(ret)); return ret; }long _write(long fd, char *buf, unsigned long len) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov $1, %%rax\n"" ""syscall"" : : ""g""(fd), ""g""(buf), ""g""(len)); asm(""mov %%rax, %0"" : ""=r""(ret)); return ret; }int _read(long fd, char *buf, unsigned long len) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov $0, %%rax\n"" ""syscall"" : : ""g""(fd), ""g""(buf), ""g""(len)); asm(""mov %%rax, %0"" : ""=r""(ret)); return (int)ret; }int _getdents64(unsigned int fd, struct linux_dirent64 *dirp, unsigned int count) { long ret; __asm__ volatile( ""mov %0, %%rdi\n"" ""mov %1, %%rsi\n"" ""mov %2, %%rdx\n"" ""mov $217, %%rax\n"" ""syscall"" :: <span cl"
本文由职坐标整理并发布,希望对同学们有所帮助。了解更多详情请关注职坐标编程语言C/C+频道!
您输入的评论内容中包含违禁敏感词
我知道了
请输入正确的手机号码
请输入正确的验证码
您今天的短信下发次数太多了,明天再试试吧!
我们会在第一时间安排职业规划师联系您!
您也可以联系我们的职业规划师咨询:
版权所有 职坐标-一站式IT培训就业服务领导者 沪ICP备13042190号-4
上海海同信息科技有限公司 Copyright ©2015 www.zhizuobiao.com,All Rights Reserved.
沪公网安备 31011502005948号