begriffs open source - freertos/blob - portable/RVDS/ARM7

1 ;/*

2 ; * FreeRTOS SMP Kernel V202110.00

4 ; *

5 ; * Permission is hereby granted, free of charge, to any person obtaining a copy of

6 ; * this software and associated documentation files (the "Software"), to deal in

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10 ; * subject to the following conditions:

11 ; *

12 ; * The above copyright notice and this permission notice shall be included in all

13 ; * copies or substantial portions of the Software.

14 ; *

15 ; * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

16 ; * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS

17 ; * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR

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22 ; * https://www.FreeRTOS.org

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24 ; *

25 ; * 1 tab == 4 spaces!

26 ; */

27

28 INCLUDE portmacro.inc

29

30 IMPORT vTaskSwitchContext

31 IMPORT xTaskIncrementTick

32

33 EXPORT vPortYieldProcessor

34 EXPORT vPortStartFirstTask

35 EXPORT vPreemptiveTick

36 EXPORT vPortYield

37

38

39 VICVECTADDR EQU 0xFFFFF030

40 T0IR EQU 0xE0004000

41 T0MATCHBIT EQU 0x00000001

42

43 ARM

44 AREA PORT_ASM, CODE, READONLY

45

46

47

48 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

49 ; Starting the first task is done by just restoring the context

50 ; setup by pxPortInitialiseStack

51 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

52 vPortStartFirstTask

53

54 PRESERVE8

55

56 portRESTORE_CONTEXT

57

58 vPortYield

59

60 PRESERVE8

61

62 SVC 0

63 bx lr

64

65 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

66 ; Interrupt service routine for the SWI interrupt. The vector table is

67 ; configured in the startup.s file.

68 ;

69 ; vPortYieldProcessor() is used to manually force a context switch. The

70 ; SWI interrupt is generated by a call to taskYIELD() or portYIELD().

71 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

72

73 vPortYieldProcessor

74

75 PRESERVE8

76

77 ; Within an IRQ ISR the link register has an offset from the true return

78 ; address, but an SWI ISR does not. Add the offset manually so the same

79 ; ISR return code can be used in both cases.

80 ADD LR, LR, #4

81

82 ; Perform the context switch.

83 portSAVE_CONTEXT ; Save current task context

84 LDR R0, =vTaskSwitchContext ; Get the address of the context switch function

85 MOV LR, PC ; Store the return address

86 BX R0 ; Call the contedxt switch function

87 portRESTORE_CONTEXT ; restore the context of the selected task

88

89

90

91 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

92 ; Interrupt service routine for preemptive scheduler tick timer

93 ; Only used if portUSE_PREEMPTION is set to 1 in portmacro.h

94 ;

95 ; Uses timer 0 of LPC21XX Family

96 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

97

98 vPreemptiveTick

99

100 PRESERVE8

101

102 portSAVE_CONTEXT ; Save the context of the current task.

103

104 LDR R0, =xTaskIncrementTick ; Increment the tick count.

105 MOV LR, PC ; This may make a delayed task ready

106 BX R0 ; to run.

107

108 CMP R0, #0

109 BEQ SkipContextSwitch

110 LDR R0, =vTaskSwitchContext ; Find the highest priority task that

111 MOV LR, PC ; is ready to run.

112 BX R0

113 SkipContextSwitch

114 MOV R0, #T0MATCHBIT ; Clear the timer event

115 LDR R1, =T0IR

116 STR R0, [R1]

117

118 LDR R0, =VICVECTADDR ; Acknowledge the interrupt

119 STR R0,[R0]

120

121 portRESTORE_CONTEXT ; Restore the context of the highest

122 ; priority task that is ready to run.

123 END

124