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 /** ThreadX Component */ 17 /** */ 18 /** Thread */ 19 /** */ 20 /**************************************************************************/ 21 /**************************************************************************/ 22 23 24 #define TX_SOURCE_CODE 25 26 27 /* Include necessary system files. */ 28 29 #include "tx_api.h" 30 #include "tx_thread.h" 31 #include "tx_timer.h" 32 33 34 /**************************************************************************/ 35 /* */ 36 /* FUNCTION RELEASE */ 37 /* */ 38 /* _tx_thread_context_save Win32/Visual */ 39 /* 6.1 */ 40 /* AUTHOR */ 41 /* */ 42 /* William E. Lamie, Microsoft Corporation */ 43 /* */ 44 /* DESCRIPTION */ 45 /* */ 46 /* This function saves the context of an executing thread in the */ 47 /* beginning of interrupt processing. The function also ensures that */ 48 /* the system stack is used upon return to the calling ISR. */ 49 /* */ 50 /* INPUT */ 51 /* */ 52 /* None */ 53 /* */ 54 /* OUTPUT */ 55 /* */ 56 /* None */ 57 /* */ 58 /* CALLS */ 59 /* */ 60 /* SuspendThread Win32 thread suspend */ 61 /* _tx_win32_critical_section_obtain Obtain critical section */ 62 /* _tx_win32_critical_section_release Release critical section */ 63 /* */ 64 /* CALLED BY */ 65 /* */ 66 /* ISRs */ 67 /* */ 68 /* RELEASE HISTORY */ 69 /* */ 70 /* DATE NAME DESCRIPTION */ 71 /* */ 72 /* 09-30-2020 William E. Lamie Initial Version 6.1 */ 73 /* */ 74 /**************************************************************************/ _tx_thread_context_save(VOID)75VOID _tx_thread_context_save(VOID) 76 { 77 78 TX_THREAD *thread_ptr; 79 80 81 /* Enter critical section to ensure other threads are not playing with 82 the core ThreadX data structures. */ 83 _tx_win32_critical_section_obtain(&_tx_win32_critical_section); 84 85 /* Debug entry. */ 86 _tx_win32_debug_entry_insert("CONTEXT_SAVE", __FILE__, __LINE__); 87 88 /* Pickup the current thread pointer. */ 89 thread_ptr = _tx_thread_current_ptr; 90 91 /* If an application thread is running, suspend it to simulate preemption. */ 92 if ((thread_ptr) && (_tx_thread_system_state == 0)) 93 { 94 95 /* Yes, this is the first interrupt and an application thread is running... 96 suspend it! */ 97 98 /* Suspend the thread to simulate preemption. Note that the thread is suspended BEFORE the protection get 99 flag is checked to ensure there is not a race condition between this thread and the update of that flag. */ 100 SuspendThread(thread_ptr -> tx_thread_win32_thread_handle); 101 102 /* Debug entry. */ 103 _tx_win32_debug_entry_insert("CONTEXT_SAVE-suspend_thread", __FILE__, __LINE__); 104 105 } 106 107 /* Increment the nested interrupt condition. */ 108 _tx_thread_system_state++; 109 110 /* Exit Win32 critical section. */ 111 _tx_win32_critical_section_release(&_tx_win32_critical_section); 112 } 113 114
