添加rtthread相关代码

riscv/rtthread/components/libc/posix/io/mman/mman.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author            Notes
+ * 2017/11/30     Bernard           The first version.
+ * 2024/03/29     TroyMitchelle     Add all function comments
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+
+#include <rtthread.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/errno.h>
+
+#include "sys/mman.h"
+
+/**
+ * @brief   Maps a region of memory into the calling process's address space.
+ * @param   addr    Desired starting address of the mapping.
+ * @param   length  Length of the mapping.
+ * @param   prot    Protection of the mapped memory region.
+ * @param   flags   Type of the mapped memory region.
+ * @param   fd      File descriptor of the file to be mapped.
+ * @param   offset  Offset within the file to start the mapping.
+ * @return  Upon success, returns a pointer to the mapped region; otherwise, MAP_FAILED is returned.
+ */
+void *mmap(void *addr, size_t length, int prot, int flags,
+    int fd, off_t offset)
+{
+    uint8_t *mem;
+
+    if (addr)
+    {
+        mem = addr;
+    }
+    else mem = (uint8_t *)malloc(length);
+
+    if (mem)
+    {
+        off_t cur;
+        size_t read_bytes;
+
+        cur = lseek(fd, 0, SEEK_SET);
+
+        lseek(fd, offset, SEEK_SET);
+        read_bytes = read(fd, mem, length);
+        if (read_bytes != length)
+        {
+            if (addr == RT_NULL)
+            {
+                /* read failed */
+                free(mem);
+                mem = RT_NULL;
+            }
+        }
+        lseek(fd, cur, SEEK_SET);
+
+        return mem;
+    }
+
+    errno = ENOMEM;
+
+    return MAP_FAILED;
+}
+
+/**
+ * @brief   Unmaps a mapped region of memory.
+ * @param   addr    Starting address of the mapping to be unmapped.
+ * @param   length  Length of the mapping.
+ * @return  Upon success, returns 0; otherwise, -1 is returned.
+ */
+int munmap(void *addr, size_t length)
+{
+    if (addr)
+    {
+        free(addr);
+        return 0;
+    }
+
+    return -1;
+}