| /* | |
| FreeRTOS V8.1.0 - Copyright (C) 2014 Real Time Engineers Ltd. | |
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| */ | |
| /* | |
| Changes from V2.6.0 | |
| + AVR port - Replaced the inb() and outb() functions with direct memory | |
| access. This allows the port to be built with the 20050414 build of | |
| WinAVR. | |
| */ | |
| #include <stdlib.h> | |
| #include <avr/interrupt.h> | |
| #include "FreeRTOS.h" | |
| #include "task.h" | |
| /*----------------------------------------------------------- | |
| * Implementation of functions defined in portable.h for the AVR port. | |
| *----------------------------------------------------------*/ | |
| /* Start tasks with interrupts enables. */ | |
| #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 ) | |
| /* Hardware constants for timer 1. */ | |
| #define portCLEAR_COUNTER_ON_MATCH ( ( uint8_t ) 0x08 ) | |
| #define portPRESCALE_64 ( ( uint8_t ) 0x03 ) | |
| #define portCLOCK_PRESCALER ( ( uint32_t ) 64 ) | |
| #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( uint8_t ) 0x10 ) | |
| /*-----------------------------------------------------------*/ | |
| /* We require the address of the pxCurrentTCB variable, but don't want to know | |
| any details of its type. */ | |
| typedef void TCB_t; | |
| extern volatile TCB_t * volatile pxCurrentTCB; | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Macro to save all the general purpose registers, the save the stack pointer | |
| * into the TCB. | |
| * | |
| * The first thing we do is save the flags then disable interrupts. This is to | |
| * guard our stack against having a context switch interrupt after we have already | |
| * pushed the registers onto the stack - causing the 32 registers to be on the | |
| * stack twice. | |
| * | |
| * r1 is set to zero as the compiler expects it to be thus, however some | |
| * of the math routines make use of R1. | |
| * | |
| * The interrupts will have been disabled during the call to portSAVE_CONTEXT() | |
| * so we need not worry about reading/writing to the stack pointer. | |
| */ | |
| #define portSAVE_CONTEXT() \ | |
| asm volatile ( "push r0 \n\t" \ | |
| "in r0, __SREG__ \n\t" \ | |
| "cli \n\t" \ | |
| "push r0 \n\t" \ | |
| "push r1 \n\t" \ | |
| "clr r1 \n\t" \ | |
| "push r2 \n\t" \ | |
| "push r3 \n\t" \ | |
| "push r4 \n\t" \ | |
| "push r5 \n\t" \ | |
| "push r6 \n\t" \ | |
| "push r7 \n\t" \ | |
| "push r8 \n\t" \ | |
| "push r9 \n\t" \ | |
| "push r10 \n\t" \ | |
| "push r11 \n\t" \ | |
| "push r12 \n\t" \ | |
| "push r13 \n\t" \ | |
| "push r14 \n\t" \ | |
| "push r15 \n\t" \ | |
| "push r16 \n\t" \ | |
| "push r17 \n\t" \ | |
| "push r18 \n\t" \ | |
| "push r19 \n\t" \ | |
| "push r20 \n\t" \ | |
| "push r21 \n\t" \ | |
| "push r22 \n\t" \ | |
| "push r23 \n\t" \ | |
| "push r24 \n\t" \ | |
| "push r25 \n\t" \ | |
| "push r26 \n\t" \ | |
| "push r27 \n\t" \ | |
| "push r28 \n\t" \ | |
| "push r29 \n\t" \ | |
| "push r30 \n\t" \ | |
| "push r31 \n\t" \ | |
| "lds r26, pxCurrentTCB \n\t" \ | |
| "lds r27, pxCurrentTCB + 1 \n\t" \ | |
| "in r0, 0x3d \n\t" \ | |
| "st x+, r0 \n\t" \ | |
| "in r0, 0x3e \n\t" \ | |
| "st x+, r0 \n\t" \ | |
| ); | |
| /* | |
| * Opposite to portSAVE_CONTEXT(). Interrupts will have been disabled during | |
| * the context save so we can write to the stack pointer. | |
| */ | |
| #define portRESTORE_CONTEXT() \ | |
| asm volatile ( "lds r26, pxCurrentTCB \n\t" \ | |
| "lds r27, pxCurrentTCB + 1 \n\t" \ | |
| "ld r28, x+ \n\t" \ | |
| "out __SP_L__, r28 \n\t" \ | |
| "ld r29, x+ \n\t" \ | |
| "out __SP_H__, r29 \n\t" \ | |
| "pop r31 \n\t" \ | |
| "pop r30 \n\t" \ | |
| "pop r29 \n\t" \ | |
| "pop r28 \n\t" \ | |
| "pop r27 \n\t" \ | |
| "pop r26 \n\t" \ | |
| "pop r25 \n\t" \ | |
| "pop r24 \n\t" \ | |
| "pop r23 \n\t" \ | |
| "pop r22 \n\t" \ | |
| "pop r21 \n\t" \ | |
| "pop r20 \n\t" \ | |
| "pop r19 \n\t" \ | |
| "pop r18 \n\t" \ | |
| "pop r17 \n\t" \ | |
| "pop r16 \n\t" \ | |
| "pop r15 \n\t" \ | |
| "pop r14 \n\t" \ | |
| "pop r13 \n\t" \ | |
| "pop r12 \n\t" \ | |
| "pop r11 \n\t" \ | |
| "pop r10 \n\t" \ | |
| "pop r9 \n\t" \ | |
| "pop r8 \n\t" \ | |
| "pop r7 \n\t" \ | |
| "pop r6 \n\t" \ | |
| "pop r5 \n\t" \ | |
| "pop r4 \n\t" \ | |
| "pop r3 \n\t" \ | |
| "pop r2 \n\t" \ | |
| "pop r1 \n\t" \ | |
| "pop r0 \n\t" \ | |
| "out __SREG__, r0 \n\t" \ | |
| "pop r0 \n\t" \ | |
| ); | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Perform hardware setup to enable ticks from timer 1, compare match A. | |
| */ | |
| static void prvSetupTimerInterrupt( void ); | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * See header file for description. | |
| */ | |
| StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters ) | |
| { | |
| uint16_t usAddress; | |
| /* Place a few bytes of known values on the bottom of the stack. | |
| This is just useful for debugging. */ | |
| *pxTopOfStack = 0x11; | |
| pxTopOfStack--; | |
| *pxTopOfStack = 0x22; | |
| pxTopOfStack--; | |
| *pxTopOfStack = 0x33; | |
| pxTopOfStack--; | |
| /* Simulate how the stack would look after a call to vPortYield() generated by | |
| the compiler. */ | |
| /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */ | |
| /* The start of the task code will be popped off the stack last, so place | |
| it on first. */ | |
| usAddress = ( uint16_t ) pxCode; | |
| *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
| pxTopOfStack--; | |
| usAddress >>= 8; | |
| *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
| pxTopOfStack--; | |
| /* Next simulate the stack as if after a call to portSAVE_CONTEXT(). | |
| portSAVE_CONTEXT places the flags on the stack immediately after r0 | |
| to ensure the interrupts get disabled as soon as possible, and so ensuring | |
| the stack use is minimal should a context switch interrupt occur. */ | |
| *pxTopOfStack = ( StackType_t ) 0x00; /* R0 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = portFLAGS_INT_ENABLED; | |
| pxTopOfStack--; | |
| /* Now the remaining registers. The compiler expects R1 to be 0. */ | |
| *pxTopOfStack = ( StackType_t ) 0x00; /* R1 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x02; /* R2 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x03; /* R3 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x04; /* R4 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x05; /* R5 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x06; /* R6 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x07; /* R7 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x08; /* R8 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x09; /* R9 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x10; /* R10 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x11; /* R11 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x12; /* R12 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x13; /* R13 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x14; /* R14 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x15; /* R15 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x16; /* R16 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x17; /* R17 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x18; /* R18 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x19; /* R19 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x20; /* R20 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x21; /* R21 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x22; /* R22 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x23; /* R23 */ | |
| pxTopOfStack--; | |
| /* Place the parameter on the stack in the expected location. */ | |
| usAddress = ( uint16_t ) pvParameters; | |
| *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
| pxTopOfStack--; | |
| usAddress >>= 8; | |
| *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x26; /* R26 X */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x27; /* R27 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x28; /* R28 Y */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x29; /* R29 */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x30; /* R30 Z */ | |
| pxTopOfStack--; | |
| *pxTopOfStack = ( StackType_t ) 0x031; /* R31 */ | |
| pxTopOfStack--; | |
| /*lint +e950 +e611 +e923 */ | |
| return pxTopOfStack; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| BaseType_t xPortStartScheduler( void ) | |
| { | |
| /* Setup the hardware to generate the tick. */ | |
| prvSetupTimerInterrupt(); | |
| /* Restore the context of the first task that is going to run. */ | |
| portRESTORE_CONTEXT(); | |
| /* Simulate a function call end as generated by the compiler. We will now | |
| jump to the start of the task the context of which we have just restored. */ | |
| asm volatile ( "ret" ); | |
| /* Should not get here. */ | |
| return pdTRUE; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| void vPortEndScheduler( void ) | |
| { | |
| /* It is unlikely that the AVR port will get stopped. If required simply | |
| disable the tick interrupt here. */ | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Manual context switch. The first thing we do is save the registers so we | |
| * can use a naked attribute. | |
| */ | |
| void vPortYield( void ) __attribute__ ( ( naked ) ); | |
| void vPortYield( void ) | |
| { | |
| portSAVE_CONTEXT(); | |
| vTaskSwitchContext(); | |
| portRESTORE_CONTEXT(); | |
| asm volatile ( "ret" ); | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Context switch function used by the tick. This must be identical to | |
| * vPortYield() from the call to vTaskSwitchContext() onwards. The only | |
| * difference from vPortYield() is the tick count is incremented as the | |
| * call comes from the tick ISR. | |
| */ | |
| void vPortYieldFromTick( void ) __attribute__ ( ( naked ) ); | |
| void vPortYieldFromTick( void ) | |
| { | |
| portSAVE_CONTEXT(); | |
| if( xTaskIncrementTick() != pdFALSE ) | |
| { | |
| vTaskSwitchContext(); | |
| } | |
| portRESTORE_CONTEXT(); | |
| asm volatile ( "ret" ); | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Setup timer 1 compare match A to generate a tick interrupt. | |
| */ | |
| static void prvSetupTimerInterrupt( void ) | |
| { | |
| uint32_t ulCompareMatch; | |
| uint8_t ucHighByte, ucLowByte; | |
| /* Using 16bit timer 1 to generate the tick. Correct fuses must be | |
| selected for the configCPU_CLOCK_HZ clock. */ | |
| ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ; | |
| /* We only have 16 bits so have to scale to get our required tick rate. */ | |
| ulCompareMatch /= portCLOCK_PRESCALER; | |
| /* Adjust for correct value. */ | |
| ulCompareMatch -= ( uint32_t ) 1; | |
| /* Setup compare match value for compare match A. Interrupts are disabled | |
| before this is called so we need not worry here. */ | |
| ucLowByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff ); | |
| ulCompareMatch >>= 8; | |
| ucHighByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff ); | |
| OCR1AH = ucHighByte; | |
| OCR1AL = ucLowByte; | |
| /* Setup clock source and compare match behaviour. */ | |
| ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64; | |
| TCCR1B = ucLowByte; | |
| /* Enable the interrupt - this is okay as interrupt are currently globally | |
| disabled. */ | |
| ucLowByte = TIMSK; | |
| ucLowByte |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE; | |
| TIMSK = ucLowByte; | |
| } | |
| /*-----------------------------------------------------------*/ | |
| #if configUSE_PREEMPTION == 1 | |
| /* | |
| * Tick ISR for preemptive scheduler. We can use a naked attribute as | |
| * the context is saved at the start of vPortYieldFromTick(). The tick | |
| * count is incremented after the context is saved. | |
| */ | |
| void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal, naked ) ); | |
| void SIG_OUTPUT_COMPARE1A( void ) | |
| { | |
| vPortYieldFromTick(); | |
| asm volatile ( "reti" ); | |
| } | |
| #else | |
| /* | |
| * Tick ISR for the cooperative scheduler. All this does is increment the | |
| * tick count. We don't need to switch context, this can only be done by | |
| * manual calls to taskYIELD(); | |
| */ | |
| void SIG_OUTPUT_COMPARE1A( void ) __attribute__ ( ( signal ) ); | |
| void SIG_OUTPUT_COMPARE1A( void ) | |
| { | |
| xTaskIncrementTick(); | |
| } | |
| #endif | |