static int handle_nand_info_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
-       nand_device_t *p;
        int i = 0;
        int j = 0;
        int first = -1;
        int last = -1;
 
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
+
        switch (argc) {
        default:
                return ERROR_COMMAND_SYNTAX_ERROR;
                last = INT32_MAX;
                break;
        case 2:
-               first = last = strtoul(args[1], NULL, 0);
+               COMMAND_PARSE_NUMBER(int, args[1], i);
+               first = last = i;
+               i = 0;
                break;
        case 3:
-               first = strtoul(args[1], NULL, 0);
-               last = strtoul(args[2], NULL, 0);
+               COMMAND_PARSE_NUMBER(int, args[1], first);
+               COMMAND_PARSE_NUMBER(int, args[2], last);
                break;
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
        if (p)
        {
                if (p->device)
 
 static int handle_nand_probe_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
-       nand_device_t *p;
-       int retval;
-
        if (argc != 1)
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
+
        if (p)
        {
                if ((retval = nand_probe(p)) == ERROR_OK)
                        command_print(cmd_ctx, "unknown error when probing NAND flash device");
                }
        }
-       else
-       {
-               command_print(cmd_ctx, "NAND flash device '#%s' is out of bounds", args[0]);
-       }
 
        return ERROR_OK;
 }
 
 static int handle_nand_erase_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
-       nand_device_t *p;
-       int retval;
-
        if (argc != 1 && argc != 3)
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
 
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
+
        if (p)
        {
-               char *cp;
                unsigned long offset;
                unsigned long length;
 
                if (argc == 3) {
                        unsigned long size = p->erase_size * p->num_blocks;
 
-                       offset = strtoul(args[1], &cp, 0);
-                       if (*cp || (offset == ULONG_MAX)
-                                       || (offset % p->erase_size) != 0
-                                       || offset >= size)
+                       COMMAND_PARSE_NUMBER(ulong, args[1], offset);
+                       if ((offset % p->erase_size) != 0 || offset >= size)
                                return ERROR_INVALID_ARGUMENTS;
 
-                       length = strtoul(args[2], &cp, 0);
-                       if (*cp || (length == ULONG_MAX)
-                                       || (length == 0)
-                                       || (length % p->erase_size) != 0
+                       COMMAND_PARSE_NUMBER(ulong, args[2], length);
+                       if ((length == 0) || (length % p->erase_size) != 0
                                        || (length + offset) > size)
                                return ERROR_INVALID_ARGUMENTS;
 
                        command_print(cmd_ctx, "unknown error when erasing NAND flash device");
                }
        }
-       else
-       {
-               command_print(cmd_ctx, "NAND flash device '#%s' is out of bounds", args[0]);
-       }
 
        return ERROR_OK;
 }
 
 int handle_nand_check_bad_blocks_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
-       nand_device_t *p;
-       int retval;
        int first = -1;
        int last = -1;
 
 
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
-       if (!p) {
-               command_print(cmd_ctx, "NAND flash device '#%s' is out of bounds",
-                               args[0]);
-               return ERROR_INVALID_ARGUMENTS;
-       }
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
 
        if (argc == 3)
        {
-               char *cp;
                unsigned long offset;
                unsigned long length;
 
-               offset = strtoul(args[1], &cp, 0);
-               if (*cp || offset == ULONG_MAX || offset % p->erase_size)
-               {
+               COMMAND_PARSE_NUMBER(ulong, args[1], offset);
+               if (offset % p->erase_size)
                        return ERROR_INVALID_ARGUMENTS;
-               }
                offset /= p->erase_size;
 
-               length = strtoul(args[2], &cp, 0);
-               if (*cp || length == ULONG_MAX || length % p->erase_size)
-               {
+               COMMAND_PARSE_NUMBER(ulong, args[2], length);
+               if (length % p->erase_size)
                        return ERROR_INVALID_ARGUMENTS;
-               }
+
                length -= 1;
                length /= p->erase_size;
 
        duration_t duration;
        char *duration_text;
 
-       nand_device_t *p;
-
        if (argc < 3)
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
-
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
+
        if (p)
        {
                uint8_t *page = NULL;
                uint32_t oob_size = 0;
                const int *eccpos = NULL;
 
-               offset = strtoul(args[2], NULL, 0);
+               COMMAND_PARSE_NUMBER(u32, args[2], offset);
 
                if (argc > 3)
                {
                free(duration_text);
                duration_text = NULL;
        }
-       else
-       {
-               command_print(cmd_ctx, "NAND flash device '#%s' is out of bounds", args[0]);
-       }
 
        return ERROR_OK;
 }
 
 static int handle_nand_dump_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
-       nand_device_t *p;
-
        if (argc < 4)
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
+
        if (p)
        {
                if (p->device)
                        uint32_t page_size = 0;
                        uint8_t *oob = NULL;
                        uint32_t oob_size = 0;
-                       uint32_t address = strtoul(args[2], NULL, 0);
-                       uint32_t size = strtoul(args[3], NULL, 0);
+                       uint32_t address;
+                       COMMAND_PARSE_NUMBER(u32, args[2], address);
+                       uint32_t size;
+                       COMMAND_PARSE_NUMBER(u32, args[3], size);
                        uint32_t bytes_done = 0;
                        enum oob_formats oob_format = NAND_OOB_NONE;
 
                        command_print(cmd_ctx, "#%s: not probed", args[0]);
                }
        }
-       else
-       {
-               command_print(cmd_ctx, "NAND flash device '#%s' is out of bounds", args[0]);
-       }
 
        return ERROR_OK;
 }
 
 static int handle_nand_raw_access_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
 {
-       nand_device_t *p;
-
        if ((argc < 1) || (argc > 2))
        {
                return ERROR_COMMAND_SYNTAX_ERROR;
        }
 
-       p = get_nand_device_by_num(strtoul(args[0], NULL, 0));
+       nand_device_t *p;
+       int retval = nand_command_get_device_by_num(cmd_ctx, args[0], &p);
+       if (ERROR_OK != retval)
+               return retval;
+
        if (p)
        {
                if (p->device)
                        command_print(cmd_ctx, "#%s: not probed", args[0]);
                }
        }
-       else
-       {
-               command_print(cmd_ctx, "NAND flash device '#%s' is out of bounds", args[0]);
-       }
 
        return ERROR_OK;
 }