2 * FreeRTOS Kernel V10.0.0
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3 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software. If you wish to use our Amazon
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14 * FreeRTOS name, please do so in a fair use way that does not cause confusion.
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16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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18 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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19 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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20 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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23 * http://www.FreeRTOS.org
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24 * http://aws.amazon.com/freertos
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26 * 1 tab == 4 spaces!
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30 /*-----------------------------------------------------------
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31 * Implementation of functions defined in portable.h for the Tern EE 186
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33 *----------------------------------------------------------*/
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35 /* Library includes. */
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36 #include <embedded.h>
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39 /* Scheduler includes. */
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40 #include "FreeRTOS.h"
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42 #include "portasm.h"
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44 /* The timer increments every four clocks, hence the divide by 4. */
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45 #define portPRESCALE_VALUE ( 16 )
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46 #define portTIMER_COMPARE ( configCPU_CLOCK_HZ / ( configTICK_RATE_HZ * 4UL ) )
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48 /* From the RDC data sheet. */
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49 #define portENABLE_TIMER_AND_INTERRUPT ( uint16_t ) 0xe00b
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50 #define portENABLE_TIMER ( uint16_t ) 0xC001
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52 /* Interrupt control. */
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53 #define portEIO_REGISTER 0xff22
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54 #define portCLEAR_INTERRUPT 0x0008
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56 /* Setup the hardware to generate the required tick frequency. */
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57 static void prvSetupTimerInterrupt( void );
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59 /* The ISR used depends on whether the preemptive or cooperative scheduler
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61 #if( configUSE_PREEMPTION == 1 )
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62 /* Tick service routine used by the scheduler when preemptive scheduling is
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64 static void __interrupt __far prvPreemptiveTick( void );
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66 /* Tick service routine used by the scheduler when cooperative scheduling is
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68 static void __interrupt __far prvNonPreemptiveTick( void );
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71 /* Trap routine used by taskYIELD() to manually cause a context switch. */
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72 static void __interrupt __far prvYieldProcessor( void );
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74 /*-----------------------------------------------------------*/
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75 /* See header file for description. */
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76 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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78 StackType_t DS_Reg = 0;
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80 /* We need the true data segment. */
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81 __asm{ MOV DS_Reg, DS };
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83 /* Place a few bytes of known values on the bottom of the stack.
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84 This is just useful for debugging. */
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86 *pxTopOfStack = 0x1111;
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88 *pxTopOfStack = 0x2222;
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90 *pxTopOfStack = 0x3333;
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93 /* We are going to start the scheduler using a return from interrupt
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94 instruction to load the program counter, so first there would be the
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95 function call with parameters preamble. */
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97 *pxTopOfStack = FP_OFF( pvParameters );
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99 *pxTopOfStack = FP_OFF( pxCode );
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102 /* Next the status register and interrupt return address. */
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103 *pxTopOfStack = portINITIAL_SW;
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105 *pxTopOfStack = FP_SEG( pxCode );
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107 *pxTopOfStack = FP_OFF( pxCode );
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110 /* The remaining registers would be pushed on the stack by our context
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111 switch function. These are loaded with values simply to make debugging
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113 *pxTopOfStack = ( StackType_t ) 0xAAAA; /* AX */
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115 *pxTopOfStack = ( StackType_t ) 0xBBBB; /* BX */
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117 *pxTopOfStack = ( StackType_t ) 0xCCCC; /* CX */
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119 *pxTopOfStack = ( StackType_t ) 0xDDDD; /* DX */
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121 *pxTopOfStack = ( StackType_t ) 0xEEEE; /* ES */
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124 *pxTopOfStack = DS_Reg; /* DS */
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126 *pxTopOfStack = ( StackType_t ) 0x0123; /* SI */
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128 *pxTopOfStack = ( StackType_t ) 0xDDDD; /* DI */
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130 *pxTopOfStack = ( StackType_t ) 0xBBBB; /* BP */
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132 return pxTopOfStack;
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134 /*-----------------------------------------------------------*/
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136 BaseType_t xPortStartScheduler( void )
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138 /* This is called with interrupts already disabled. */
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140 /* Put our manual switch (yield) function on a known
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142 setvect( portSWITCH_INT_NUMBER, prvYieldProcessor );
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144 /* Setup the tick interrupt. */
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145 prvSetupTimerInterrupt();
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147 /* Kick off the scheduler by setting up the context of the first task. */
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148 portFIRST_CONTEXT();
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150 /* Should not get here! */
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153 /*-----------------------------------------------------------*/
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155 /* The ISR used depends on whether the preemptive or cooperative scheduler
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157 #if( configUSE_PREEMPTION == 1 )
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158 static void __interrupt __far prvPreemptiveTick( void )
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160 /* Get the scheduler to update the task states following the tick. */
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161 if( xTaskIncrementTick() != pdFALSE )
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163 /* Switch in the context of the next task to be run. */
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164 portEND_SWITCHING_ISR();
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167 /* Reset interrupt. */
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168 outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
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171 static void __interrupt __far prvNonPreemptiveTick( void )
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173 /* Same as preemptive tick, but the cooperative scheduler is being used
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174 so we don't have to switch in the context of the next task. */
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175 xTaskIncrementTick();
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177 /* Reset interrupt. */
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178 outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
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181 /*-----------------------------------------------------------*/
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183 static void __interrupt __far prvYieldProcessor( void )
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185 /* Switch in the context of the next task to be run. */
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186 portEND_SWITCHING_ISR();
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188 /*-----------------------------------------------------------*/
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190 void vPortEndScheduler( void )
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192 /* Not implemented. */
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194 /*-----------------------------------------------------------*/
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196 static void prvSetupTimerInterrupt( void )
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198 const uint32_t ulCompareValue = portTIMER_COMPARE;
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199 uint16_t usTimerCompare;
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201 usTimerCompare = ( uint16_t ) ( ulCompareValue >> 4 );
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202 t2_init( portENABLE_TIMER, portPRESCALE_VALUE, NULL );
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204 #if( configUSE_PREEMPTION == 1 )
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205 /* Tick service routine used by the scheduler when preemptive scheduling is
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207 t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvPreemptiveTick );
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209 /* Tick service routine used by the scheduler when cooperative scheduling is
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211 t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvNonPreemptiveTick );
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