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 #define TX_SOURCE_CODE 24 25 26 /* Include necessary system files. */ 27 28 #include "tx_api.h" 29 #include "tx_thread.h" 30 31 32 /**************************************************************************/ 33 /* */ 34 /* FUNCTION RELEASE */ 35 /* */ 36 /* _tx_thread_system_preempt_check PORTABLE C */ 37 /* 6.1 */ 38 /* AUTHOR */ 39 /* */ 40 /* William E. Lamie, Microsoft Corporation */ 41 /* */ 42 /* DESCRIPTION */ 43 /* */ 44 /* This function checks for preemption that could have occurred as a */ 45 /* result scheduling activities occurring while the preempt disable */ 46 /* flag was set. */ 47 /* */ 48 /* INPUT */ 49 /* */ 50 /* None */ 51 /* */ 52 /* OUTPUT */ 53 /* */ 54 /* None */ 55 /* */ 56 /* CALLS */ 57 /* */ 58 /* _tx_thread_system_return Return to the system */ 59 /* */ 60 /* CALLED BY */ 61 /* */ 62 /* Other ThreadX Components */ 63 /* */ 64 /* RELEASE HISTORY */ 65 /* */ 66 /* DATE NAME DESCRIPTION */ 67 /* */ 68 /* 05-19-2020 William E. Lamie Initial Version 6.0 */ 69 /* 09-30-2020 Yuxin Zhou Modified comment(s), */ 70 /* resulting in version 6.1 */ 71 /* */ 72 /**************************************************************************/ _tx_thread_system_preempt_check(VOID)73VOID _tx_thread_system_preempt_check(VOID) 74 { 75 76 ULONG combined_flags; 77 TX_THREAD *current_thread; 78 TX_THREAD *thread_ptr; 79 80 81 /* Combine the system state and preempt disable flags into one for comparison. */ 82 TX_THREAD_SYSTEM_RETURN_CHECK(combined_flags) 83 84 /* Determine if we are in a system state (ISR or Initialization) or internal preemption is disabled. */ 85 if (combined_flags == ((ULONG) 0)) 86 { 87 88 /* No, at thread execution level so continue checking for preemption. */ 89 90 /* Pickup thread pointer. */ 91 TX_THREAD_GET_CURRENT(current_thread) 92 93 /* Pickup the next execute pointer. */ 94 thread_ptr = _tx_thread_execute_ptr; 95 96 /* Determine if preemption should take place. */ 97 if (current_thread != thread_ptr) 98 { 99 100 #ifdef TX_ENABLE_STACK_CHECKING 101 102 /* Check this thread's stack. */ 103 TX_THREAD_STACK_CHECK(thread_ptr) 104 #endif 105 106 107 #ifdef TX_THREAD_ENABLE_PERFORMANCE_INFO 108 109 /* Determine if an idle system return is present. */ 110 if (thread_ptr == TX_NULL) 111 { 112 113 /* Yes, increment the return to idle return count. */ 114 _tx_thread_performance_idle_return_count++; 115 } 116 else 117 { 118 119 /* No, there is another thread ready to run and will be scheduled upon return. */ 120 _tx_thread_performance_non_idle_return_count++; 121 } 122 #endif 123 124 /* Return to the system so the higher priority thread can be scheduled. */ 125 _tx_thread_system_return(); 126 } 127 } 128 } 129 130
