[libc] implement extension standard C functions (#6044)

* implement extension standard C functions

1 files changed, 60 insertions, 0 deletions

diff --git a/components/libc/compilers/common/include/sys/select.h b/components/libc/compilers/common/include/sys/select.h
new file mode 100644
index 0000000000..9004658be9
--- /dev/null
+++ b/components/libc/compilers/common/include/sys/select.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2006-2022, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2021-07-21     Meco Man     The first version
+ * 2021-12-25     Meco Man     Handle newlib 2.2.0 or lower version
+ */
+
+#ifndef __SYS_SELECT_H__
+#define __SYS_SELECT_H__
+
+#include <rtthread.h>
+#include <sys/types.h>
+#include <sys/time.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef  FD_SETSIZE
+#define  FD_SETSIZE  32
+#endif
+
+#ifdef SAL_USING_POSIX
+#ifdef FD_SETSIZE
+#undef FD_SETSIZE
+#endif
+#define FD_SETSIZE      DFS_FD_MAX
+#endif /* SAL_USING_POSIX */
+
+typedef long    fd_mask;
+
+#ifndef _SYS_TYPES_FD_SET /* Newlib 2.2.0 or lower version */
+#define   NBBY    8       /* number of bits in a byte */
+#define   NFDBITS (sizeof (fd_mask) * NBBY)   /* bits per mask */
+#ifndef   howmany
+#define   howmany(x,y)    (((x)+((y)-1))/(y))
+#endif /* howmany */
+
+typedef struct _types_fd_set {
+    fd_mask fds_bits[howmany(FD_SETSIZE, NFDBITS)];
+} _types_fd_set;
+#define fd_set _types_fd_set
+
+#define FD_SET(n, p)    ((p)->fds_bits[(n)/NFDBITS] |= (1L << ((n) % NFDBITS)))
+#define FD_CLR(n, p)    ((p)->fds_bits[(n)/NFDBITS] &= ~(1L << ((n) % NFDBITS)))
+#define FD_ISSET(n, p)  ((p)->fds_bits[(n)/NFDBITS] & (1L << ((n) % NFDBITS)))
+#define FD_ZERO(p)      rt_memset((void*)(p), 0, sizeof(*(p)))
+#endif /* _SYS_TYPES_FD_SET */
+
+int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __SYS_SELECT_H__ */