minimalc/arch/x86_64.c

#if defined(__x86_64__)
#include "../int.h"

#define SYS_EXIT 60
void exit(int8_t status) {
  asm volatile(
    "syscall"
    :
    : "a"(SYS_EXIT), "D"(status)
    :
  );
  for(;;);
}

#define SYS_WRITE 1
intptr_t write(int32_t fd, const void* buf, intptr_t size) {
  intptr_t n_written = 0;
  asm volatile (
      "syscall\n"
      "movq %0, %%rax\n"
      : "=r"(n_written)
      : "a"(SYS_WRITE), "D"(fd), "S"(buf), "d"(size)  // RDI, RSI, RDX are used in x86-64 for write args
      : "rcx", "r11"
  );
  return n_written;
}

#define SYS_READ 0
intptr_t read(int32_t fd, const void* buf, intptr_t size) {
  intptr_t n_read = 0;
  asm volatile (
      "syscall\n"
      "movq %0, %%rax\n"
      : "=r"(n_read)
      : "a"(SYS_READ), "D"(fd), "S"(buf), "d"(size)  // RDI, RSI, RDX are used in x86-64 for write args
      : "rcx", "r11", "memory"
  );
  return n_read;
}

#define SYS_FORK 57
uint32_t fork() {
  uint64_t rtn;
  asm volatile(
    "syscall\n"         // syscall
    "movq %0, %%rax\n"    // save return value
    : "=r"(rtn)
    : "a"(SYS_FORK)
    :
  );
  return (uint32_t)rtn;
}

#define SYS_OPENAT 257
int32_t openat(int32_t fd, const char* filename, uint32_t flags, uint32_t mode) {
  int32_t file;
  asm volatile (
      "mov %5, %%r10\n"
      "syscall\n"
      : "=a"(file)
      : "a"(SYS_OPENAT), "D"(fd), "S"(filename), "d"(flags), "r"((uint64_t)mode)  // RDI, RSI, RDX are used in x86-64 for write args
      : "rcx", "r10", "r11"
  );
  return file;
}

#define SYS_CLOSE 3
int close(unsigned int fd) {
  int rtn;
  asm volatile(
    "syscall"
    : "=a"(rtn)
    : "a"(SYS_CLOSE), "D"(fd)
    : "rcx", "r11"
  );
  return rtn;
}

#define SYS_FSYNC 74
int fsync(unsigned int fd) {
  int rtn;
  asm volatile(
    "syscall"
    : "=a"(rtn)
    : "a"(SYS_FSYNC), "D"(fd)
    : "rcx", "r11"
  );
  return rtn;
}

#define SYS_SOCKET 41
int socket(int domain, int type, int protocol) {
  int32_t fd;
  asm volatile (
    "syscall\n"
    : "=a"(fd)
    : "a"(SYS_SOCKET), "D"(domain), "S"(type), "d"(protocol)
    : "rcx", "r11"
  );
  return fd;
}

#define SYS_SETSOCKOPT 54
int setsockopt(int fd, int level, int optname, const void* optval, socklen_t optlen) {
  int rtn;
  asm volatile(
    "mov %5, %%r10\n"
    "mov %6, %%r8\n"
    "syscall\n"
    : "=a"(rtn)
    : "a"(SYS_SETSOCKOPT), "D"(fd), "S"(level), "d"(optname), "r"(optval), "r"((uint64_t)optlen)
    : "rcx", "r11"
  );
  return rtn;
}

#define SYS_BIND 49
int bind(int fd, const void* sockaddr, socklen_t addrlen) {
  int rtn;
  asm volatile(
    "syscall\n"
    : "=a"(rtn)
    : "a"(SYS_BIND), "D"(fd), "S"(sockaddr), "d"(addrlen)
    : "rcx", "r11"
  );
  return rtn;
}

#define SYS_LISTEN 50
int listen(int fd, int backlog) {
  int rtn;
  asm volatile(
    "syscall\n"
    : "=a"(rtn)
    : "a"(SYS_LISTEN), "D"(fd), "S"(backlog)
    : "rcx", "r11"
  );
  return rtn;
}

#define SYS_ACCEPT 43
int accept(int fd, void* addr, socklen_t* addrlen) {
  int rtn;
  asm volatile(
    "syscall\n"
    : "=a"(rtn)
    : "a"(SYS_ACCEPT), "D"(fd), "S"(addr), "d"(addrlen)
    : "rcx", "r11", "memory"
  );
  return rtn;
}

#define SYS_CONNECT 42
int connect(int fd, void* addr, socklen_t addrlen) {
  int rtn;
  asm volatile(
    "syscall\n"
    : "=a"(rtn)
    : "a"(SYS_CONNECT), "D"(fd), "S"(addr), "d"(addrlen)
    : "rcx", "r11"
  );
  return rtn;
}

#define SYS_SENDTO 44
ssize_t sendto(int fd, const void* buf, size_t size, int flags, const void* sockaddr, socklen_t addrlen) {
  ssize_t nsent;
  asm volatile(
    "mov %5, %%r10\n"
    "mov %6, %%r8\n"
    "mov %7, %%r9\n"
    "syscall\n"
    : "=a"(nsent)
    : "a"(SYS_SENDTO), "D"(fd), "S"(buf), "d"(size), "r"((int64_t)flags), "r"(sockaddr), "r"((uint64_t)addrlen)
    : "rcx", "r11"
  );
  return nsent;
}

#define SYS_RECVFROM 45
ssize_t recvfrom(int fd, const void* buf, size_t size, int flags, const void* sockaddr, socklen_t addrlen) {
  ssize_t nrecv;
  asm volatile(
    "mov %5, %%r10\n"
    "mov %6, %%r8\n"
    "mov %7, %%r9\n"
    "syscall\n"
    : "=a"(nrecv)
    : "a"(SYS_RECVFROM), "D"(fd), "S"(buf), "d"(size), "r"((int64_t)flags), "r"(sockaddr), "r"((int64_t)addrlen)
    : "rcx", "r11", "memory"
  );
  return nrecv;
}

#endif /* ifdef __x86_64__ */