/* * FreeRTOS Kernel V10.3.1 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of * the Software, and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * http://www.FreeRTOS.org * http://aws.amazon.com/freertos * * 1 tab == 4 spaces! */ /* IAR includes. */ #include /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" #if configUSE_PORT_OPTIMISED_TASK_SELECTION == 1 /* Check the configuration. */ #if ( configMAX_PRIORITIES > 32 ) #error configUSE_PORT_OPTIMISED_TASK_SELECTION can only be set to 1 when configMAX_PRIORITIES is less than or equal to 32. It is very rare that a system requires more than 10 to 15 difference priorities as tasks that share a priority will time slice. #endif #endif /* configUSE_PORT_OPTIMISED_TASK_SELECTION */ #ifndef configSETUP_TICK_INTERRUPT #error configSETUP_TICK_INTERRUPT() must be defined in FreeRTOSConfig.h to call the function that sets up the tick interrupt. A default that uses the PIT is provided in the official demo application. #endif #ifndef configCLEAR_TICK_INTERRUPT #error configCLEAR_TICK_INTERRUPT must be defined in FreeRTOSConfig.h to clear which ever interrupt was used to generate the tick interrupt. A default that uses the PIT is provided in the official demo application. #endif /* A critical section is exited when the critical section nesting count reaches * this value. */ #define portNO_CRITICAL_NESTING ( ( uint32_t ) 0 ) /* Tasks are not created with a floating point context, but can be given a * floating point context after they have been created. A variable is stored as * part of the tasks context that holds portNO_FLOATING_POINT_CONTEXT if the task * does not have an FPU context, or any other value if the task does have an FPU * context. */ #define portNO_FLOATING_POINT_CONTEXT ( ( StackType_t ) 0 ) /* Constants required to setup the initial task context. */ #define portINITIAL_SPSR ( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */ #define portTHUMB_MODE_BIT ( ( StackType_t ) 0x20 ) #define portTHUMB_MODE_ADDRESS ( 0x01UL ) /* Masks all bits in the APSR other than the mode bits. */ #define portAPSR_MODE_BITS_MASK ( 0x1F ) /* The value of the mode bits in the APSR when the CPU is executing in user * mode. */ #define portAPSR_USER_MODE ( 0x10 ) /*-----------------------------------------------------------*/ /* * Starts the first task executing. This function is necessarily written in * assembly code so is implemented in portASM.s. */ extern void vPortRestoreTaskContext( void ); /* * Used to catch tasks that attempt to return from their implementing function. */ static void prvTaskExitError( void ); /*-----------------------------------------------------------*/ /* A variable is used to keep track of the critical section nesting. This * variable has to be stored as part of the task context and must be initialised to * a non zero value to ensure interrupts don't inadvertently become unmasked before * the scheduler starts. As it is stored as part of the task context it will * automatically be set to 0 when the first task is started. */ volatile uint32_t ulCriticalNesting = 9999UL; /* Saved as part of the task context. If ulPortTaskHasFPUContext is non-zero * then a floating point context must be saved and restored for the task. */ uint32_t ulPortTaskHasFPUContext = pdFALSE; /* Set to 1 to pend a context switch from an ISR. */ uint32_t ulPortYieldRequired = pdFALSE; /* Counts the interrupt nesting depth. A context switch is only performed if * if the nesting depth is 0. */ uint32_t ulPortInterruptNesting = 0UL; /*-----------------------------------------------------------*/ /* * See header file for description. */ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack, TaskFunction_t pxCode, void * pvParameters ) { /* Setup the initial stack of the task. The stack is set exactly as * expected by the portRESTORE_CONTEXT() macro. * * The fist real value on the stack is the status register, which is set for * system mode, with interrupts enabled. A few NULLs are added first to ensure * GDB does not try decoding a non-existent return address. */ *pxTopOfStack = NULL; pxTopOfStack--; *pxTopOfStack = NULL; pxTopOfStack--; *pxTopOfStack = NULL; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) portINITIAL_SPSR; if( ( ( uint32_t ) pxCode & portTHUMB_MODE_ADDRESS ) != 0x00UL ) { /* The task will start in THUMB mode. */ *pxTopOfStack |= portTHUMB_MODE_BIT; } pxTopOfStack--; /* Next the return address, which in this case is the start of the task. */ *pxTopOfStack = ( StackType_t ) pxCode; pxTopOfStack--; /* Next all the registers other than the stack pointer. */ *pxTopOfStack = ( StackType_t ) prvTaskExitError; /* R14 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */ pxTopOfStack--; /* The task will start with a critical nesting count of 0 as interrupts are * enabled. */ *pxTopOfStack = portNO_CRITICAL_NESTING; pxTopOfStack--; /* The task will start without a floating point context. A task that uses * the floating point hardware must call vPortTaskUsesFPU() before executing * any floating point instructions. */ *pxTopOfStack = portNO_FLOATING_POINT_CONTEXT; return pxTopOfStack; } /*-----------------------------------------------------------*/ static void prvTaskExitError( void ) { /* A function that implements a task must not exit or attempt to return to * its caller as there is nothing to return to. If a task wants to exit it * should instead call vTaskDelete( NULL ). * * Artificially force an assert() to be triggered if configASSERT() is * defined, then stop here so application writers can catch the error. */ configASSERT( ulPortInterruptNesting == ~0UL ); portDISABLE_INTERRUPTS(); for( ; ; ) { } } /*-----------------------------------------------------------*/ BaseType_t xPortStartScheduler( void ) { uint32_t ulAPSR; /* Only continue if the CPU is not in User mode. The CPU must be in a * Privileged mode for the scheduler to start. */ __asm volatile ( "MRS %0, APSR" : "=r" ( ulAPSR ) ); ulAPSR &= portAPSR_MODE_BITS_MASK; configASSERT( ulAPSR != portAPSR_USER_MODE ); if( ulAPSR != portAPSR_USER_MODE ) { /* Start the timer that generates the tick ISR. */ configSETUP_TICK_INTERRUPT(); vPortRestoreTaskContext(); } /* Will only get here if vTaskStartScheduler() was called with the CPU in * a non-privileged mode or the binary point register was not set to its lowest * possible value. */ return 0; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* Not implemented in ports where there is nothing to return to. * Artificially force an assert. */ configASSERT( ulCriticalNesting == 1000UL ); } /*-----------------------------------------------------------*/ void vPortEnterCritical( void ) { portDISABLE_INTERRUPTS(); /* Now interrupts are disabled ulCriticalNesting can be accessed * directly. Increment ulCriticalNesting to keep a count of how many times * portENTER_CRITICAL() has been called. */ ulCriticalNesting++; /* This is not the interrupt safe version of the enter critical function so * assert() if it is being called from an interrupt context. Only API * functions that end in "FromISR" can be used in an interrupt. Only assert if * the critical nesting count is 1 to protect against recursive calls if the * assert function also uses a critical section. */ if( ulCriticalNesting == 1 ) { configASSERT( ulPortInterruptNesting == 0 ); } } /*-----------------------------------------------------------*/ void vPortExitCritical( void ) { if( ulCriticalNesting > portNO_CRITICAL_NESTING ) { /* Decrement the nesting count as the critical section is being * exited. */ ulCriticalNesting--; /* If the nesting level has reached zero then all interrupt * priorities must be re-enabled. */ if( ulCriticalNesting == portNO_CRITICAL_NESTING ) { /* Critical nesting has reached zero so all interrupt priorities * should be unmasked. */ portENABLE_INTERRUPTS(); } } } /*-----------------------------------------------------------*/ void FreeRTOS_Tick_Handler( void ) { portDISABLE_INTERRUPTS(); /* Increment the RTOS tick. */ if( xTaskIncrementTick() != pdFALSE ) { ulPortYieldRequired = pdTRUE; } portENABLE_INTERRUPTS(); configCLEAR_TICK_INTERRUPT(); } /*-----------------------------------------------------------*/ void vPortTaskUsesFPU( void ) { uint32_t ulInitialFPSCR = 0; /* A task is registering the fact that it needs an FPU context. Set the * FPU flag (which is saved as part of the task context). */ ulPortTaskHasFPUContext = pdTRUE; /* Initialise the floating point status register. */ __asm( "FMXR FPSCR, %0"::"r" ( ulInitialFPSCR ) ); } /*-----------------------------------------------------------*/