/* * FreeRTOS Kernel V10.0.0 * Copyright (C) 2017 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. If you wish to use our Amazon * FreeRTOS name, please do so in a fair use way that does not cause confusion. * * 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! */ /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the ARM CM0 port. *----------------------------------------------------------*/ /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /* * Start first task is a separate function so it can be tested in isolation. */ void vPortStartFirstTask( void ); /* * Exception handlers. */ void xPortPendSVHandler( void ); void vPortSVCHandler( void ); /*-----------------------------------------------------------*/ __asm void vPortSVCHandler( void ) { /* This function is no longer used, but retained for backward compatibility. */ } /*-----------------------------------------------------------*/ __asm void vPortStartFirstTask( void ) { PRESERVE8 EXTERN __Vectors /* Use the NVIC offset register to locate the stack. */ ldr r0, =__Vectors ldr r0, [r0] /* Set the msp back to the start of the stack. */ msr msp, r0 ldr r3, =pxCurrentTCB /* Obtain location of pxCurrentTCB. */ ldr r1, [r3] ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */ adds r0, #32 /* Discard everything up to r0. */ msr psp, r0 /* This is now the new top of stack to use in the task. */ movs r0, #2 /* Switch to the psp stack. */ msr CONTROL, r0 pop {r0-r5} /* Pop the registers that are saved automatically. */ mov lr, r5 /* lr is now in r5. */ cpsie i /* The first task has its context and interrupts can be enabled. */ pop {pc} /* Finally, pop the PC to jump to the user defined task code. */ ALIGN } /*-----------------------------------------------------------*/ __asm void xPortPendSVHandler( void ) { extern vPortSafeTaskSwitchContext extern pxCurrentTCB PRESERVE8 mrs r0, psp ldr r3, =pxCurrentTCB /* Get the location of the current TCB. */ ldr r2, [r3] subs r0, #32 /* Make space for the remaining low registers. */ str r0, [r2] /* Save the new top of stack. */ stmia r0!, {r4-r7} /* Store the low registers that are not saved automatically. */ mov r4, r8 /* Store the high registers. */ mov r5, r9 mov r6, r10 mov r7, r11 stmia r0!, {r4-r7} push {r3, r14} bl vPortSafeTaskSwitchContext pop {r2, r3} /* lr goes in r3. r2 now holds tcb pointer. */ ldr r1, [r2] ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */ adds r0, #16 /* Move to the high registers. */ ldmia r0!, {r4-r7} /* Pop the high registers. */ mov r8, r4 mov r9, r5 mov r10, r6 mov r11, r7 msr psp, r0 /* Remember the new top of stack for the task. */ subs r0, #32 /* Go back for the low registers that are not automatically restored. */ ldmia r0!, {r4-r7} /* Pop low registers. */ bx r3 ALIGN } /*-----------------------------------------------------------*/