/* FreeRTOS V7.3.0 - Copyright (C) 2012 Real Time Engineers Ltd. FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION. *************************************************************************** * * * FreeRTOS tutorial books are available in pdf and paperback. * * Complete, revised, and edited pdf reference manuals are also * * available. * * * * Purchasing FreeRTOS documentation will not only help you, by * * ensuring you get running as quickly as possible and with an * * in-depth knowledge of how to use FreeRTOS, it will also help * * the FreeRTOS project to continue with its mission of providing * * professional grade, cross platform, de facto standard solutions * * for microcontrollers - completely free of charge! * * * * >>> See http://www.FreeRTOS.org/Documentation for details. <<< * * * * Thank you for using FreeRTOS, and thank you for your support! * * * *************************************************************************** This file is part of the FreeRTOS distribution. FreeRTOS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (version 2) as published by the Free Software Foundation AND MODIFIED BY the FreeRTOS exception. >>>NOTE<<< The modification to the GPL is included to allow you to distribute a combined work that includes FreeRTOS without being obliged to provide the source code for proprietary components outside of the FreeRTOS kernel. FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License and the FreeRTOS license exception along with FreeRTOS; if not it can be viewed here: http://www.freertos.org/a00114.html and also obtained by writing to Richard Barry, contact details for whom are available on the FreeRTOS WEB site. 1 tab == 4 spaces! *************************************************************************** * * * Having a problem? Start by reading the FAQ "My application does * * not run, what could be wrong?" * * * * http://www.FreeRTOS.org/FAQHelp.html * * * *************************************************************************** http://www.FreeRTOS.org - Documentation, training, latest versions, license and contact details. http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products, including FreeRTOS+Trace - an indispensable productivity tool. Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell the code with commercial support, indemnification, and middleware, under the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also provide a safety engineered and independently SIL3 certified version under the SafeRTOS brand: http://www.SafeRTOS.com. */ #include "FreeRTOSConfig.h" #define portCONTEXT_SIZE 132 #define portEPC_STACK_LOCATION 124 #define portSTATUS_STACK_LOCATION 128 /******************************************************************/ .macro portSAVE_CONTEXT /* Make room for the context. First save the current status so we can manipulate it, and the cause and EPC registers so we capture their original values in case of interrupt nesting. */ mfc0 k0, _CP0_CAUSE addiu sp, sp, -portCONTEXT_SIZE mfc0 k1, _CP0_STATUS /* Also save s6 and s5 so we can use them during this interrupt. Any nesting interrupts should maintain the values of these registers across the ISR. */ sw s6, 44(sp) sw s5, 40(sp) sw k1, portSTATUS_STACK_LOCATION(sp) /* Enable interrupts above the current priority. */ srl k0, k0, 0xa ins k1, k0, 10, 6 ins k1, zero, 1, 4 /* s5 is used as the frame pointer. */ add s5, zero, sp /* Check the nesting count value. */ la k0, uxInterruptNesting lw s6, (k0) /* If the nesting count is 0 then swap to the the system stack, otherwise the system stack is already being used. */ bne s6, zero, .+20 nop /* Swap to the system stack. */ la sp, xISRStackTop lw sp, (sp) /* Increment and save the nesting count. */ addiu s6, s6, 1 sw s6, 0(k0) /* s6 holds the EPC value, this is saved after interrupts are re-enabled. */ mfc0 s6, _CP0_EPC /* Re-enable interrupts. */ mtc0 k1, _CP0_STATUS /* Save the context into the space just created. s6 is saved again here as it now contains the EPC value. No other s registers need be saved. */ sw ra, 120(s5) sw s8, 116(s5) sw t9, 112(s5) sw t8, 108(s5) sw t7, 104(s5) sw t6, 100(s5) sw t5, 96(s5) sw t4, 92(s5) sw t3, 88(s5) sw t2, 84(s5) sw t1, 80(s5) sw t0, 76(s5) sw a3, 72(s5) sw a2, 68(s5) sw a1, 64(s5) sw a0, 60(s5) sw v1, 56(s5) sw v0, 52(s5) sw s6, portEPC_STACK_LOCATION(s5) sw $1, 16(s5) /* s6 is used as a scratch register. */ mfhi s6 sw s6, 12(s5) mflo s6 sw s6, 8(s5) /* Update the task stack pointer value if nesting is zero. */ la s6, uxInterruptNesting lw s6, (s6) addiu s6, s6, -1 bne s6, zero, .+20 nop /* Save the stack pointer. */ la s6, uxSavedTaskStackPointer sw s5, (s6) .endm /******************************************************************/ .macro portRESTORE_CONTEXT /* Restore the stack pointer from the TCB. This is only done if the nesting count is 1. */ la s6, uxInterruptNesting lw s6, (s6) addiu s6, s6, -1 bne s6, zero, .+20 nop la s6, uxSavedTaskStackPointer lw s5, (s6) /* Restore the context. */ lw s6, 8(s5) mtlo s6 lw s6, 12(s5) mthi s6 lw $1, 16(s5) /* s6 is loaded as it was used as a scratch register and therefore saved as part of the interrupt context. */ lw s6, 44(s5) lw v0, 52(s5) lw v1, 56(s5) lw a0, 60(s5) lw a1, 64(s5) lw a2, 68(s5) lw a3, 72(s5) lw t0, 76(s5) lw t1, 80(s5) lw t2, 84(s5) lw t3, 88(s5) lw t4, 92(s5) lw t5, 96(s5) lw t6, 100(s5) lw t7, 104(s5) lw t8, 108(s5) lw t9, 112(s5) lw s8, 116(s5) lw ra, 120(s5) /* Protect access to the k registers, and others. */ di /* Decrement the nesting count. */ la k0, uxInterruptNesting lw k1, (k0) addiu k1, k1, -1 sw k1, 0(k0) lw k0, portSTATUS_STACK_LOCATION(s5) lw k1, portEPC_STACK_LOCATION(s5) /* Leave the stack how we found it. First load sp from s5, then restore s5 from the stack. */ add sp, zero, s5 lw s5, 40(sp) addiu sp, sp, portCONTEXT_SIZE mtc0 k0, _CP0_STATUS mtc0 k1, _CP0_EPC eret nop .endm