#include "syscall.h"
#include "thread.h"

/* 无参数的系统调用 */
#define _syscall0(NUMBER) ({				       \
   int retval;					               \
   asm volatile (					       \
   "int $0x80"						       \
   : "=a" (retval)					       \
   : "a" (NUMBER)					       \
   : "memory"						       \
   );							       \
   retval;						       \
})

/* 一个参数的系统调用 */
#define _syscall1(NUMBER, ARG1) ({			       \
   int retval;					               \
   asm volatile (					       \
   "int $0x80"						       \
   : "=a" (retval)					       \
   : "a" (NUMBER), "b" (ARG1)				       \
   : "memory"						       \
   );							       \
   retval;						       \
})

/* 两个参数的系统调用 */
#define _syscall2(NUMBER, ARG1, ARG2) ({		       \
   int retval;						       \
   asm volatile (					       \
   "int $0x80"						       \
   : "=a" (retval)					       \
   : "a" (NUMBER), "b" (ARG1), "c" (ARG2)		       \
   : "memory"						       \
   );							       \
   retval;						       \
})

/* 三个参数的系统调用 */
#define _syscall3(NUMBER, ARG1, ARG2, ARG3) ({		       \
   int retval;						       \
   asm volatile (					       \
      "int $0x80"					       \
      : "=a" (retval)					       \
      : "a" (NUMBER), "b" (ARG1), "c" (ARG2), "d" (ARG3)       \
      : "memory"					       \
   );							       \
   retval;						       \
})

/* 返回当前任务pid */
uint32_t getpid() {
   return _syscall0(SYS_GETPID);
}

/* 把buf中count个字符写入文件描述符fd */
uint32_t write(int32_t fd, const void* buf, uint32_t count) {
   return _syscall3(SYS_WRITE, fd, buf, count);
}

/* 申请size字节大小的内存,并返回结果 */
void* malloc(uint32_t size) {
   return (void*)_syscall1(SYS_MALLOC, size);
}

/* 释放ptr指向的内存 */
void free(void* ptr) {
   _syscall1(SYS_FREE, ptr);
}

/* 派生子进程,返回子进程pid */
pid_t fork(void){
   return _syscall0(SYS_FORK);
}

/* 从文件描述符fd中读取count个字节到buf */
int32_t read(int32_t fd, void* buf, uint32_t count) {
   return _syscall3(SYS_READ, fd, buf, count);
}

/* 输出一个字符 */
void putchar(char char_asci) {
   _syscall1(SYS_PUTCHAR, char_asci);
}

/* 清空屏幕 */
void clear(void) {
   _syscall0(SYS_CLEAR);
}

/* 获取当前工作目录 */
char* getcwd(char* buf, uint32_t size) {
   return (char*)_syscall2(SYS_GETCWD, buf, size);
}

/* 以flag方式打开文件pathname */
int32_t open(char* pathname, uint8_t flag) {
   return _syscall2(SYS_OPEN, pathname, flag);
}

/* 关闭文件fd */
int32_t close(int32_t fd) {
   return _syscall1(SYS_CLOSE, fd);
}

/* 设置文件偏移量 */
int32_t lseek(int32_t fd, int32_t offset, uint8_t whence) {
   return _syscall3(SYS_LSEEK, fd, offset, whence);
}

/* 删除文件pathname */
int32_t unlink(const char* pathname) {
   return _syscall1(SYS_UNLINK, pathname);
}

/* 创建目录pathname */
int32_t mkdir(const char* pathname) {
   return _syscall1(SYS_MKDIR, pathname);
}

/* 打开目录name */
struct dir* opendir(const char* name) {
   return (struct dir*)_syscall1(SYS_OPENDIR, name);
}

/* 关闭目录dir */
int32_t closedir(struct dir* dir) {
   return _syscall1(SYS_CLOSEDIR, dir);
}

/* 删除目录pathname */
int32_t rmdir(const char* pathname) {
   return _syscall1(SYS_RMDIR, pathname);
}

/* 读取目录dir */
struct dir_entry* readdir(struct dir* dir) {
   return (struct dir_entry*)_syscall1(SYS_READDIR, dir);
}

/* 回归目录指针 */
void rewinddir(struct dir* dir) {
   _syscall1(SYS_REWINDDIR, dir);
}

/* 获取path属性到buf中 */
int32_t stat(const char* path, struct stat* buf) {
   return _syscall2(SYS_STAT, path, buf);
}

/* 改变工作目录为path */
int32_t chdir(const char* path) {
   return _syscall1(SYS_CHDIR, path);
}

/* 显示任务列表 */
void ps(void) {
   _syscall0(SYS_PS);
}

int execv(const char* pathname, char** argv) {
   return _syscall2(SYS_EXECV, pathname, argv);
}