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jeremybenn |
RSEG ICODE:CODE
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CODE32
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EXTERN vTaskSwitchContext
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EXTERN vTaskIncrementTick
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PUBLIC vPortYieldProcessor
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PUBLIC vPortPreemptiveTick
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PUBLIC vPortStartFirstTask
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#include "AT91SAM7S64_inc.h"
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#include "ISR_Support.h"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Starting the first task is just a matter of restoring the context that
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; was created by pxPortInitialiseStack().
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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vPortStartFirstTask:
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portRESTORE_CONTEXT
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Manual context switch function. This is the SWI hander.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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vPortYieldProcessor:
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ADD LR, LR, #4 ; Add 4 to the LR to make the LR appear exactly
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; as if the context was saved during and IRQ
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; handler.
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portSAVE_CONTEXT ; Save the context of the current task...
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LDR R0, =vTaskSwitchContext ; before selecting the next task to execute.
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mov lr, pc
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BX R0
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portRESTORE_CONTEXT ; Restore the context of the selected task.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Preemptive context switch function. This will only ever get installed if
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; portUSE_PREEMPTION is set to 1 in portmacro.h.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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vPortPreemptiveTick:
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portSAVE_CONTEXT ; Save the context of the current task.
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LDR R0, =vTaskIncrementTick ; Increment the tick count - this may wake a task.
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mov lr, pc
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BX R0
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LDR R0, =vTaskSwitchContext ; Select the next task to execute.
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mov lr, pc
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BX R0
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LDR R14, =AT91C_BASE_PITC ; Clear the PIT interrupt
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LDR R0, [R14, #PITC_PIVR ]
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LDR R14, =AT91C_BASE_AIC ; Mark the End of Interrupt on the AIC
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STR R14, [R14, #AIC_EOICR]
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portRESTORE_CONTEXT ; Restore the context of the selected task.
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END
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