2 * FreeRTOS Kernel V10.3.0
\r
3 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
\r
5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
\r
6 * this software and associated documentation files (the "Software"), to deal in
\r
7 * the Software without restriction, including without limitation the rights to
\r
8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
\r
9 * the Software, and to permit persons to whom the Software is furnished to do so,
\r
10 * subject to the following conditions:
\r
12 * The above copyright notice and this permission notice shall be included in all
\r
13 * copies or substantial portions of the Software.
\r
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
\r
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
\r
17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
\r
18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
\r
19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
\r
20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
\r
22 * http://www.FreeRTOS.org
\r
23 * http://aws.amazon.com/freertos
\r
25 * 1 tab == 4 spaces!
\r
29 /*-----------------------------------------------------------
\r
30 * Implementation of functions defined in portable.h for the Tern EE 186
\r
32 *----------------------------------------------------------*/
\r
34 /* Library includes. */
\r
35 #include <embedded.h>
\r
38 /* Scheduler includes. */
\r
39 #include "FreeRTOS.h"
\r
41 #include "portasm.h"
\r
43 /* The timer increments every four clocks, hence the divide by 4. */
\r
44 #define portPRESCALE_VALUE ( 16 )
\r
45 #define portTIMER_COMPARE ( configCPU_CLOCK_HZ / ( configTICK_RATE_HZ * 4UL ) )
\r
47 /* From the RDC data sheet. */
\r
48 #define portENABLE_TIMER_AND_INTERRUPT ( uint16_t ) 0xe00b
\r
49 #define portENABLE_TIMER ( uint16_t ) 0xC001
\r
51 /* Interrupt control. */
\r
52 #define portEIO_REGISTER 0xff22
\r
53 #define portCLEAR_INTERRUPT 0x0008
\r
55 /* Setup the hardware to generate the required tick frequency. */
\r
56 static void prvSetupTimerInterrupt( void );
\r
58 /* The ISR used depends on whether the preemptive or cooperative scheduler
\r
60 #if( configUSE_PREEMPTION == 1 )
\r
61 /* Tick service routine used by the scheduler when preemptive scheduling is
\r
63 static void __interrupt __far prvPreemptiveTick( void );
\r
65 /* Tick service routine used by the scheduler when cooperative scheduling is
\r
67 static void __interrupt __far prvNonPreemptiveTick( void );
\r
70 /* Trap routine used by taskYIELD() to manually cause a context switch. */
\r
71 static void __interrupt __far prvYieldProcessor( void );
\r
73 /*-----------------------------------------------------------*/
\r
74 /* See header file for description. */
\r
75 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
\r
77 StackType_t DS_Reg = 0;
\r
79 /* We need the true data segment. */
\r
80 __asm{ MOV DS_Reg, DS };
\r
82 /* Place a few bytes of known values on the bottom of the stack.
\r
83 This is just useful for debugging. */
\r
85 *pxTopOfStack = 0x1111;
\r
87 *pxTopOfStack = 0x2222;
\r
89 *pxTopOfStack = 0x3333;
\r
92 /* We are going to start the scheduler using a return from interrupt
\r
93 instruction to load the program counter, so first there would be the
\r
94 function call with parameters preamble. */
\r
96 *pxTopOfStack = FP_OFF( pvParameters );
\r
98 *pxTopOfStack = FP_OFF( pxCode );
\r
101 /* Next the status register and interrupt return address. */
\r
102 *pxTopOfStack = portINITIAL_SW;
\r
104 *pxTopOfStack = FP_SEG( pxCode );
\r
106 *pxTopOfStack = FP_OFF( pxCode );
\r
109 /* The remaining registers would be pushed on the stack by our context
\r
110 switch function. These are loaded with values simply to make debugging
\r
112 *pxTopOfStack = ( StackType_t ) 0xAAAA; /* AX */
\r
114 *pxTopOfStack = ( StackType_t ) 0xBBBB; /* BX */
\r
116 *pxTopOfStack = ( StackType_t ) 0xCCCC; /* CX */
\r
118 *pxTopOfStack = ( StackType_t ) 0xDDDD; /* DX */
\r
120 *pxTopOfStack = ( StackType_t ) 0xEEEE; /* ES */
\r
123 *pxTopOfStack = DS_Reg; /* DS */
\r
125 *pxTopOfStack = ( StackType_t ) 0x0123; /* SI */
\r
127 *pxTopOfStack = ( StackType_t ) 0xDDDD; /* DI */
\r
129 *pxTopOfStack = ( StackType_t ) 0xBBBB; /* BP */
\r
131 return pxTopOfStack;
\r
133 /*-----------------------------------------------------------*/
\r
135 BaseType_t xPortStartScheduler( void )
\r
137 /* This is called with interrupts already disabled. */
\r
139 /* Put our manual switch (yield) function on a known
\r
141 setvect( portSWITCH_INT_NUMBER, prvYieldProcessor );
\r
143 /* Setup the tick interrupt. */
\r
144 prvSetupTimerInterrupt();
\r
146 /* Kick off the scheduler by setting up the context of the first task. */
\r
147 portFIRST_CONTEXT();
\r
149 /* Should not get here! */
\r
152 /*-----------------------------------------------------------*/
\r
154 /* The ISR used depends on whether the preemptive or cooperative scheduler
\r
156 #if( configUSE_PREEMPTION == 1 )
\r
157 static void __interrupt __far prvPreemptiveTick( void )
\r
159 /* Get the scheduler to update the task states following the tick. */
\r
160 if( xTaskIncrementTick() != pdFALSE )
\r
162 /* Switch in the context of the next task to be run. */
\r
163 portEND_SWITCHING_ISR();
\r
166 /* Reset interrupt. */
\r
167 outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
\r
170 static void __interrupt __far prvNonPreemptiveTick( void )
\r
172 /* Same as preemptive tick, but the cooperative scheduler is being used
\r
173 so we don't have to switch in the context of the next task. */
\r
174 xTaskIncrementTick();
\r
176 /* Reset interrupt. */
\r
177 outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
\r
180 /*-----------------------------------------------------------*/
\r
182 static void __interrupt __far prvYieldProcessor( void )
\r
184 /* Switch in the context of the next task to be run. */
\r
185 portEND_SWITCHING_ISR();
\r
187 /*-----------------------------------------------------------*/
\r
189 void vPortEndScheduler( void )
\r
191 /* Not implemented. */
\r
193 /*-----------------------------------------------------------*/
\r
195 static void prvSetupTimerInterrupt( void )
\r
197 const uint32_t ulCompareValue = portTIMER_COMPARE;
\r
198 uint16_t usTimerCompare;
\r
200 usTimerCompare = ( uint16_t ) ( ulCompareValue >> 4 );
\r
201 t2_init( portENABLE_TIMER, portPRESCALE_VALUE, NULL );
\r
203 #if( configUSE_PREEMPTION == 1 )
\r
204 /* Tick service routine used by the scheduler when preemptive scheduling is
\r
206 t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvPreemptiveTick );
\r
208 /* Tick service routine used by the scheduler when cooperative scheduling is
\r
210 t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvNonPreemptiveTick );
\r