1 #ifndef __ALT_ERRNO_H__
2 #define __ALT_ERRNO_H__
3
4 /******************************************************************************
5 * *
6 * License Agreement *
7 * *
8 * Copyright (c) 2004 Altera Corporation, San Jose, California, USA. *
9 * All rights reserved. *
10 * *
11 * Permission is hereby granted, free of charge, to any person obtaining a *
12 * copy of this software and associated documentation files (the "Software"), *
13 * to deal in the Software without restriction, including without limitation *
14 * the rights to use, copy, modify, merge, publish, distribute, sublicense, *
15 * and/or sell copies of the Software, and to permit persons to whom the *
16 * Software is furnished to do so, subject to the following conditions: *
17 * *
18 * The above copyright notice and this permission notice shall be included in *
19 * all copies or substantial portions of the Software. *
20 * *
21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
22 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
23 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
24 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
25 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *
26 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *
27 * DEALINGS IN THE SOFTWARE. *
28 * *
29 * *
30 * Altera does not recommend, suggest or require that this reference design *
31 * file be used in conjunction or combination with any other product. *
32 ******************************************************************************/
33
34 /******************************************************************************
35 * *
36 * THIS IS A LIBRARY READ-ONLY SOURCE FILE. DO NOT EDIT. *
37 * *
38 ******************************************************************************/
39
40 /*
41 * errno is defined in <errno.h> so that it uses the thread local version
42 * stored in the location pointed to by "_impure_ptr". This means that the
43 * accesses to errno within the HAL library can cause the entirety of
44 * of the structure pointed to by "_impure_ptr" to be added to the
45 * users application. This can be undesirable in very small footprint systems.
46 *
47 * To avoid this happening, the HAL uses the macro ALT_ERRNO, defined below,
48 * to access errno, rather than accessing it directly. This macro will only
49 * use the thread local version if some other code has already caused it to be
50 * included into the system, otherwise it will use the global errno value.
51 *
52 * This causes a slight increases in code size where errno is accessed, but
53 * can lead to significant overall benefits in very small systems. The
54 * increase is inconsequential when compared to the size of the structure
55 * pointed to by _impure_ptr.
56 *
57 * Note that this macro accesses __errno() using an externally declared
58 * function pointer (alt_errno). This is done so that the function call uses the
59 * subroutine call instruction via a register rather than an immediate address.
60 * This is important in the case that the code has been linked for a high
61 * address, but __errno() is not being used. In this case the weak linkage
62 * would have resulted in the instruction: "call 0" which would fail to link.
63 */
64
65 extern int* (*alt_errno) (void);
66
67 /* Must define this so that values such as EBADFD are defined in errno.h. */
68 #ifndef __LINUX_ERRNO_EXTENSIONS__
69 #define __LINUX_ERRNO_EXTENSIONS__
70 #endif
71
72 #include <errno.h>
73
74 #include "alt_types.h"
75
76 #undef errno
77
78 extern int errno;
79
alt_get_errno(void)80 static ALT_INLINE int* alt_get_errno(void)
81 {
82 return ((alt_errno) ? alt_errno() : &errno);
83 }
84
85 #define ALT_ERRNO *alt_get_errno()
86
87 #endif /* __ALT_ERRNO_H__ */
88
