scmRTOS_test - Quick and dirty port of scmRTOS demo to mbed 1768…

Users » igorsk » Code » scmRTOS_test

Igor Skochinsky / Mbed 2 deprecated scmRTOS_test

Quick and dirty port of scmRTOS demo to mbed 1768. scmRTOS is a small RTOS written using C++. Offers (static) processes, critical sections, mutexes, messages, channels.

Dependencies: mbed

scmRTOS/CortexM3/OS_Target_asm.s@0:a405220cf420, 2010-09-09 (annotated)

Committer:: igorsk
Date:: Thu Sep 09 21:19:01 2010 +0000
Revision:: 0:a405220cf420

Who changed what in which revision?

User	Revision	Line number	New contents of line
igorsk	0:a405220cf420	1	; ******************************************************************************
igorsk	0:a405220cf420	2	; *
igorsk	0:a405220cf420	3	; * FULLNAME: Single-Chip Microcontroller Real-Time Operating System
igorsk	0:a405220cf420	4	; *
igorsk	0:a405220cf420	5	; * NICKNAME: scmRTOS
igorsk	0:a405220cf420	6	; *
igorsk	0:a405220cf420	7	; * PROCESSOR: ARM Cortex-M3
igorsk	0:a405220cf420	8	; *
igorsk	0:a405220cf420	9	; * TOOLKIT: EWARM (IAR Systems)
igorsk	0:a405220cf420	10	; *
igorsk	0:a405220cf420	11	; * PURPOSE: Target Dependent Low-Level Stuff
igorsk	0:a405220cf420	12	; *
igorsk	0:a405220cf420	13	; * Version: 3.10
igorsk	0:a405220cf420	14	; *
igorsk	0:a405220cf420	15	; * $Revision: 195 $
igorsk	0:a405220cf420	16	; * $Date:: 2008-06-19 #$
igorsk	0:a405220cf420	17	; *
igorsk	0:a405220cf420	18	; * Copyright (c) 2003-2010, Harry E. Zhurov
igorsk	0:a405220cf420	19	; *
igorsk	0:a405220cf420	20	; * Permission is hereby granted, free of charge, to any person
igorsk	0:a405220cf420	21	; * obtaining a copy of this software and associated documentation
igorsk	0:a405220cf420	22	; * files (the "Software"), to deal in the Software without restriction,
igorsk	0:a405220cf420	23	; * including without limitation the rights to use, copy, modify, merge,
igorsk	0:a405220cf420	24	; * publish, distribute, sublicense, and/or sell copies of the Software,
igorsk	0:a405220cf420	25	; * and to permit persons to whom the Software is furnished to do so,
igorsk	0:a405220cf420	26	; * subject to the following conditions:
igorsk	0:a405220cf420	27	; *
igorsk	0:a405220cf420	28	; * The above copyright notice and this permission notice shall be included
igorsk	0:a405220cf420	29	; * in all copies or substantial portions of the Software.
igorsk	0:a405220cf420	30	; *
igorsk	0:a405220cf420	31	; * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
igorsk	0:a405220cf420	32	; * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
igorsk	0:a405220cf420	33	; * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
igorsk	0:a405220cf420	34	; * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
igorsk	0:a405220cf420	35	; * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
igorsk	0:a405220cf420	36	; * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
igorsk	0:a405220cf420	37	; * THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
igorsk	0:a405220cf420	38	; *
igorsk	0:a405220cf420	39	; * =================================================================
igorsk	0:a405220cf420	40	; * See http://scmrtos.sourceforge.net for documentation, latest
igorsk	0:a405220cf420	41	; * information, license and contact details.
igorsk	0:a405220cf420	42	; * =================================================================
igorsk	0:a405220cf420	43	; *
igorsk	0:a405220cf420	44	; ******************************************************************************
igorsk	0:a405220cf420	45	; * Ported by Andrey Chuikin, Copyright (c) 2008-2010
igorsk	0:a405220cf420	46
igorsk	0:a405220cf420	47	; #include "scmRTOS_TARGET_CFG.h"
igorsk	0:a405220cf420	48
igorsk	0:a405220cf420	49	; -----------------------------------------------------------------------------
igorsk	0:a405220cf420	50	; PUBLIC FUNCTIONS
igorsk	0:a405220cf420	51	;
igorsk	0:a405220cf420	52	EXTERN OS_ContextSwitchHook
igorsk	0:a405220cf420	53
igorsk	0:a405220cf420	54	EXPORT OS_Start
igorsk	0:a405220cf420	55	EXPORT PendSV_Handler
igorsk	0:a405220cf420	56
igorsk	0:a405220cf420	57	; -----------------------------------------------------------------------------
igorsk	0:a405220cf420	58	; EQUATES
igorsk	0:a405220cf420	59	;
igorsk	0:a405220cf420	60	NVIC_INT_CTRL EQU 0xE000ED04 ; Interrupt control state register.
igorsk	0:a405220cf420	61	NVIC_PENDSVSET EQU 0x10000000 ; Value to trigger PendSV exception.
igorsk	0:a405220cf420	62
igorsk	0:a405220cf420	63	NVIC_SYSPRI14 EQU 0xE000ED22 ; System priority register (priority 14).
igorsk	0:a405220cf420	64	NVIC_PENDSV_PRI EQU 0xFF ; PendSV priority value (lowest).
igorsk	0:a405220cf420	65	NVIC_SYSPRI15 EQU 0xE000ED23 ; System priority register (priority 15).
igorsk	0:a405220cf420	66	NVIC_ST_PRI EQU 0xFF ; SysTick priority value (lowest).
igorsk	0:a405220cf420	67
igorsk	0:a405220cf420	68	NVIC_ST_CTRL EQU 0xE000E010 ; SysTick Ctrl & Status Reg.
igorsk	0:a405220cf420	69	NVIC_ST_RELOAD EQU 0xE000E014 ; SysTick Reload Value Reg.
igorsk	0:a405220cf420	70	NVIC_ST_CTRL_CLK_SRC EQU 0x00000004 ; Clock Source.
igorsk	0:a405220cf420	71	NVIC_ST_CTRL_INTEN EQU 0x00000002 ; Interrupt enable.
igorsk	0:a405220cf420	72	NVIC_ST_CTRL_ENABLE EQU 0x00000001 ; Counter mode.
igorsk	0:a405220cf420	73
igorsk	0:a405220cf420	74	; should be the same as in scmRTOS_TARGET_CFG.h
igorsk	0:a405220cf420	75	SYSTICKFREQ EQU 100000000
igorsk	0:a405220cf420	76	SYSTICKINTRATE EQU 1000
igorsk	0:a405220cf420	77
igorsk	0:a405220cf420	78	; -----------------------------------------------------------------------------
igorsk	0:a405220cf420	79	; CODE GENERATION DIRECTIVES
igorsk	0:a405220cf420	80	;
igorsk	0:a405220cf420	81	AREA TEXT, CODE, READONLY
igorsk	0:a405220cf420	82	THUMB
igorsk	0:a405220cf420	83
igorsk	0:a405220cf420	84	; -----------------------------------------------------------------------------
igorsk	0:a405220cf420	85	; HANDLE PendSV EXCEPTION
igorsk	0:a405220cf420	86	; void PendSV_Handler(void)
igorsk	0:a405220cf420	87	;
igorsk	0:a405220cf420	88	; Note(s) : 1) PendSV is used to cause a context switch. This is a recommended method for performing
igorsk	0:a405220cf420	89	; context switches with Cortex-M3. This is because the Cortex-M3 auto-saves half of the
igorsk	0:a405220cf420	90	; processor context on any exception, and restores same on return from exception. So only
igorsk	0:a405220cf420	91	; saving of R4-R11 is required and fixing up the stack pointers. Using the PendSV exception
igorsk	0:a405220cf420	92	; this way means that context saving and restoring is identical whether it is initiated from
igorsk	0:a405220cf420	93	; a thread or occurs due to an interrupt or exception.
igorsk	0:a405220cf420	94	;
igorsk	0:a405220cf420	95	; 2) Pseudo-code is:
igorsk	0:a405220cf420	96	; a) Get the process SP, if 0 then skip (goto f) the saving part (first context switch);
igorsk	0:a405220cf420	97	; b) Save remaining regs r4-r11 on process stack;
igorsk	0:a405220cf420	98	; c) Call OS_ContextSwitchHook for save current task SP and get new task SP;
igorsk	0:a405220cf420	99	; d) Restore R4-R11 from new process stack;
igorsk	0:a405220cf420	100	; e) Perform exception return which will restore remaining context.
igorsk	0:a405220cf420	101	; f) Get SP for the first context switch (R2 hold it);
igorsk	0:a405220cf420	102	; run SysTick; goto d);
igorsk	0:a405220cf420	103	;
igorsk	0:a405220cf420	104	; 3) On entry into PendSV handler:
igorsk	0:a405220cf420	105	; a) The following have been saved on the process stack (by processor):
igorsk	0:a405220cf420	106	; xPSR, PC, LR, R12, R0-R3
igorsk	0:a405220cf420	107	; b) Processor mode is switched to Handler mode (from Thread mode)
igorsk	0:a405220cf420	108	; c) Stack is Main stack (switched from Process stack)
igorsk	0:a405220cf420	109	;
igorsk	0:a405220cf420	110	; 4) Since PendSV is set to lowest priority in the system (by OS_Start() below), we
igorsk	0:a405220cf420	111	; know that it will only be run when no other exception or interrupt is active, and
igorsk	0:a405220cf420	112	; therefore safe to assume that context being switched out was using the process stack (PSP).
igorsk	0:a405220cf420	113	;
igorsk	0:a405220cf420	114	PendSV_Handler
igorsk	0:a405220cf420	115	CPSID I ; Prevent interruption during context switch
igorsk	0:a405220cf420	116	MRS R0, PSP ; PSP is process stack pointer
igorsk	0:a405220cf420	117	CBZ R0, nosave ; Skip register save the first time
igorsk	0:a405220cf420	118
igorsk	0:a405220cf420	119	STMDB R0!, {R4-R11} ; Save remaining regs r4-11 on process stack
igorsk	0:a405220cf420	120	; At this point, entire context of process has been saved
igorsk	0:a405220cf420	121
igorsk	0:a405220cf420	122	PUSH {R14} ; Save LR exc_return value
igorsk	0:a405220cf420	123	LDR R1, =OS_ContextSwitchHook ; OS_ContextSwitchHook();
igorsk	0:a405220cf420	124	BLX R1
igorsk	0:a405220cf420	125	POP {R14}
igorsk	0:a405220cf420	126
igorsk	0:a405220cf420	127	ContextRestore
igorsk	0:a405220cf420	128	; R0 is new process SP;
igorsk	0:a405220cf420	129	LDMIA R0!, {R4-R11} ; Restore r4-11 from new process stack
igorsk	0:a405220cf420	130	MSR PSP, R0 ; Load PSP with new process SP
igorsk	0:a405220cf420	131	ORR LR, LR, #0x04 ; Ensure exception return uses process stack
igorsk	0:a405220cf420	132	CPSIE I
igorsk	0:a405220cf420	133	BX LR ; Exception return will restore remaining context
igorsk	0:a405220cf420	134	nosave
igorsk	0:a405220cf420	135	MOV R0, R2 ; R2 hold the first task SP
igorsk	0:a405220cf420	136
igorsk	0:a405220cf420	137	LDR R1, =NVIC_ST_CTRL ; Enable and run SysTick
igorsk	0:a405220cf420	138	LDR R2, =(NVIC_ST_CTRL_CLK_SRC \| NVIC_ST_CTRL_INTEN \| NVIC_ST_CTRL_ENABLE)
igorsk	0:a405220cf420	139	STR R2, [R1]
igorsk	0:a405220cf420	140
igorsk	0:a405220cf420	141	B ContextRestore
igorsk	0:a405220cf420	142
igorsk	0:a405220cf420	143
igorsk	0:a405220cf420	144	; -----------------------------------------------------------------------------
igorsk	0:a405220cf420	145	; START MULTITASKING
igorsk	0:a405220cf420	146	; void OS_Start(TStackItem* sp)
igorsk	0:a405220cf420	147	;
igorsk	0:a405220cf420	148	; Note(s) : 1) OS_Start() MUST:
igorsk	0:a405220cf420	149	; a) Setup PendSV and SysTick exception priority to lowest;
igorsk	0:a405220cf420	150	; b) Setup SysTick (reload value);
igorsk	0:a405220cf420	151	; c) Enable interrupts (tasks will run with interrupts enabled).
igorsk	0:a405220cf420	152	;
igorsk	0:a405220cf420	153	OS_Start
igorsk	0:a405220cf420	154	LDR R1, =NVIC_SYSPRI14 ; Set the PendSV exception priority (lowest)
igorsk	0:a405220cf420	155	LDR R2, =NVIC_PENDSV_PRI
igorsk	0:a405220cf420	156	STRB R2, [R1]
igorsk	0:a405220cf420	157	LDR R1, =NVIC_SYSPRI15 ; Set the SysTick exception priority (lowest)
igorsk	0:a405220cf420	158	LDR R2, =NVIC_ST_PRI
igorsk	0:a405220cf420	159	STRB R2, [R1]
igorsk	0:a405220cf420	160
igorsk	0:a405220cf420	161	LDR R1, =NVIC_ST_RELOAD ; Setup SysTick
igorsk	0:a405220cf420	162	LDR R2, =(SYSTICKFREQ/SYSTICKINTRATE-1)
igorsk	0:a405220cf420	163	STR R2, [R1]
igorsk	0:a405220cf420	164
igorsk	0:a405220cf420	165	MOV R2, R0 ; Save the first task stack
igorsk	0:a405220cf420	166	MOVS R0, #0 ; Set the PSP to 0 for initial context switch call
igorsk	0:a405220cf420	167	MSR PSP, R0
igorsk	0:a405220cf420	168
igorsk	0:a405220cf420	169	LDR R0, =NVIC_INT_CTRL ; Trigger the PendSV exception (causes context switch)
igorsk	0:a405220cf420	170	LDR R1, =NVIC_PENDSVSET
igorsk	0:a405220cf420	171	STR R1, [R0]
igorsk	0:a405220cf420	172
igorsk	0:a405220cf420	173	CPSIE I ; Enable interrupts at processor level
igorsk	0:a405220cf420	174	loop
igorsk	0:a405220cf420	175	B loop ; Should never get here
igorsk	0:a405220cf420	176
igorsk	0:a405220cf420	177
igorsk	0:a405220cf420	178	END

Repository toolbox

Export to desktop IDE

Build repository

Repository details

Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	09 Sep 2010
Imports:	69
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	1
Followers:	4

scmRTOS/CortexM3/OS_Target_asm.s@0:a405220cf420, 2010-09-09 (annotated)

Who changed what in which revision?

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning