1 /**************************************************************************/
2 /* */
3 /* Copyright (c) Microsoft Corporation. All rights reserved. */
4 /* */
5 /* This software is licensed under the Microsoft Software License */
6 /* Terms for Microsoft Azure RTOS. Full text of the license can be */
7 /* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
8 /* and in the root directory of this software. */
9 /* */
10 /**************************************************************************/
11
12
13 /**************************************************************************/
14 /**************************************************************************/
15 /** */
16 /** POSIX wrapper for THREADX */
17 /** */
18 /** */
19 /** */
20 /**************************************************************************/
21 /**************************************************************************/
22
23 /* Include necessary system files. */
24
25 #include "tx_api.h" /* Threadx API */
26 #include "pthread.h" /* Posix API */
27 #include "px_int.h" /* Posix helper functions */
28
29
30 /**************************************************************************/
31 /* */
32 /* FUNCTION RELEASE */
33 /* */
34 /* sem_wait PORTABLE C */
35 /* 6.1.7 */
36 /* AUTHOR */
37 /* */
38 /* William E. Lamie, Microsoft Corporation */
39 /* */
40 /* DESCRIPTION */
41 /* */
42 /* This function locks (takes) a semaphore. */
43 /* */
44 /* INPUT */
45 /* */
46 /* *sem Pointer to Semaphore */
47 /* */
48 /* OUTPUT */
49 /* */
50 /* OK If successful */
51 /* ERROR If error occurs */
52 /* */
53 /* CALLS */
54 /* */
55 /* tx_thread_identify To check whether calling from a thread */
56 /* tx_semaphore_get ThreadX Semaphore get */
57 /* posix_internal_error Returns a generic error */
58 /* */
59 /* CALLED BY */
60 /* */
61 /* Application Code */
62 /* */
63 /* RELEASE HISTORY */
64 /* */
65 /* DATE NAME DESCRIPTION */
66 /* */
67 /* 06-02-2021 William E. Lamie Initial Version 6.1.7 */
68 /* */
69 /**************************************************************************/
sem_wait(sem_t * sem)70 INT sem_wait( sem_t * sem )
71 {
72
73 TX_SEMAPHORE * TheSem;
74
75
76 /* Make sure we're calling this routine from a thread context. */
77 if (! tx_thread_identify())
78 {
79 /* No wait when called from ISR. */
80 posix_internal_error(242);
81
82 /* Return Error. */
83 return (ERROR);
84 }
85
86 /* get ThreadX semaphore. */
87 TheSem = (TX_SEMAPHORE *)sem;
88
89 /* Check for an invalid semaphore pointer. */
90 if ((!TheSem) || (TheSem -> tx_semaphore_id != TX_SEMAPHORE_ID))
91 {
92 /* error in POSIX. */
93 posix_errno = EINVAL;
94 posix_set_pthread_errno(EINVAL);
95
96 /* Return error. */
97 return (EINVAL);
98 }
99 else
100 {
101 /* Takes the semaphore. */
102 if(tx_semaphore_get(TheSem,TX_WAIT_FOREVER))
103 {
104 /* Return general error. */
105 posix_internal_error(246);
106
107 /* Return error. */
108 return(ERROR);
109 }
110
111 return (OK);
112 }
113 }
114
